Complete Valve TrainInformation about the Valvetrain, Camshaft and Exhaust Header Pipe Assembly

Please check out: HOT ROD GARDEN TRACTOR PULLERS ASSOCIATION, Miller's Pulling Sled Rental and A-1 Miller's Performance Enterprises - Online Catalog
New Phone Number: 1-573-256-0313 (home/shop) | 1-573-881-7229 (cell/text)

Jump to... (Click Refresh to see changes or updates.) Optimized for 1024 x 768 screen resolution. To search for a word or phrase in any of my web sites, with Microsoft Internet Explorer 6.x, or Google Chrome, press CTRL+F to open the Find dialog box.


Information About Engine Valves -

I get so many people who tell me that when they have a problem with their engine, they cleaned and rebuilt the carburetor, but the engine would not run well, or still run the same. So they remove the carburetor, clean it again, and the engine still acts the same. So they check the carburetor again! They say they checked it, cleaned it about 10 times. (Whew) Then they move on to the ignition system, but it checks out okay, too. Anyway, I tell them if you checked and cleaned the carburetor that many times and everything looked okay with it, then the problem obviously ISN'T in the carburetor or the ignition! There are other things that help make an engine run, such as the valves. I tell them to check the valve clearances, or the engine may need a professional valve job performed. Also, check for loose valve seats. The valves are the hardest working parts in any 4-cycle engine. They need attention, too. And so many people are ignorant or know nothing about the valves, how they work or their purpose.

In most cases, the valve face will more than the seat because the moving part always wears more than the stationary part. And main thing that cause valve face wear on the exhaust valve is a worn guide, which cause the face to scrape against the seat upon closing, and/or carbon deposits being lodged between the face and seat. The intake valve face wears from guide wear also and/or either lack of an air filter or not frequently using a new air filter. Clogged filters can cause microscopic dust particles to penetrate the filter and enter the combustion chamber.

If a 4-cycle engine cranks over too easy and is hard to start, and when it (or if) does start, it loses power and/or dies for no apparent reason after running for a while, then chances are the problem is in the valves. Valve faces and/or seats become worn after many years of use, and this lessons the clearance between the valve stems and lifters, or valve stems and rocker arms. Metal contracts (shrinks) when cold and expands (swells) when hot. Knowing this, when an engine gets hot, the valves swell, especially the exhaust valve, and this lessons the clearance between the stems and lifters. The hotter a valve gets, the less clearance it will have. When there's inadequate clearance, the valves won't close all the way, or stay closed long enough to seal in sufficient compression within the combustion chamber, the engine will lose compression, making the engine hard to start and when it does start, it won't produce much power. Sometimes gas will blow out the carburetor when the engine is revved up, too. And when the engine dies for no apparent reason, it'll be almost impossible to restart when hot. To fix this, a professional valve job will need to be performed. What causes valve faces and/or seats to wear is lack of an air filter element (which will wear parts within the entire combustion chamber under dusty conditions), a dirty air filter, a defective air filter, or an air filter that has not been changed in a long time. Air filtration is very important with any engine. Especially under extreme dusty conditions. And just like fuel filters, air filters can only filter out dust particles so small. The smallest pieces of dust penetrates the microscopic holes in the filter material, and wears parts within the combustion chamber.

The valves, especially the exhaust valve, are the hardest working part of an engine. The valve face(s) can wear more than the piston rings. It's something so many mechanics overlook, yet so simple to fix.

A worn throttle shaft will also cause wear on the valve faces and seats. It's the #1 cause of most engines wearing out prematurely. If a carburetor has a worn throttle shaft, this will create a vacuum leak and the engine will idle poorly, if at all at times. Not to mention the engine will also draw in dirty air, causing wear on the valve faces/seats and piston rings, and engine will burn oil. More than .010" of play is considered too much for throttle shaft wear. Plus, at operating running speeds (3,600 rpm), the extra air will cause the engine to run lean on fuel, which will overheat the combustion chamber and cause the cylinder head to warp (blow a head gasket) and the piston and rings to wear prematurely, eventually resulting in severe engine wear and excessive oil burning. Along with regular maintenance, repair of a worn throttle shaft is required to help an engine last a long time. The most accurate way to check for amount of wear is with a dial indicator.

Performing a Professional Valve Job -

Just cleaning the valves, setting the clearances to specs and "lapping them in" is not performing a professional valve job. If the engine lacks power or dies frequently, then chances are, the valves (and seats) aren't burnt, they're just warped from normal engine heat. This happens on seasoned flathead engine blocks and OHV cylinder heads for the first time. And chances are, the valve faces are worn too, due to normal wear against the seats. This is what causes insufficient valve clearance.

Before regrounding the valve face(s) and seat(s), the valve guides should be measured for excessive wear and replaced or repaired with a thin-wall bronze sleeve if necessary, and then the valve seats can be recut or reground with valve cutting or grinding equipment to be perpendicular with the centerline of the valve guides. This is important because the cast iron or aluminum engine block (flathead) or cylinder head (OHV) can "move" or "bend and twist" just a few thousandths of an inch when it got hot for the very first time under normal operating conditions. This is called metal taking shape. Anyway, this "bending and twisting" of the metal can unseat the valve(s), and cause the engine to loose power, not idle well, and make carburetor adjustments difficult, especially at idle. I've seen this happen many times when individuals would rebuild their own engines. Valve lapping only places a rough surface on the valve face(s) and seat(s) so they'll wear-in with each other to produce a perfect seal, but the seats and faces may not be perfectly in-line with the valve stem, which can cause leaking of compression, resulting in lose of engine power.

Regrounding the valve faces at a 30° or 45° angle places the valve head in perfect alignment (perpendicular) with the stem or "straightens them out" again so they'll be good as new. And regrounding or recutting the seats at a 31° or 46° angle insures that the valve stems will be centered in the guides and the faces will seal 360° around. The reason for the 30°/31° or 45°/46° angles are so the valves and seats can wear into each other, producing a perfect 45-½° angle for each. Anyway, after the valves and seats are reground, the valve clearances can be set at .010" each with the piston positioned exactly at top dead center on the compression stroke. And then lap them in so the faces will produce a wear pattern on the seats (the lapping process helps produce the perfect 45-½° angle for each). After the valves are matched perfectly with the seats after about 2 hours of normal engine operation, the engine should start quicker, produce more power and the valves should last the life of the engine.

Ever noticed that when looking up valve clearances for an engine, the manufacturer will always show two figures? Example: Intake valve clearance: .008" - .010"; Exhaust valve clearance: .014" - .016". The greater clearance is for a fresh valve job. Because as an engine runs, due to the 30° or 45° angle on the valve face(s) and the 31° or 46° angle on the seat(s), the valves and the seats wears together (break-in period), forming a 30-½° or 45-½° angle on each, which causes the clearances to become slightly lessened. (As the valves wears into the seats, forming a perfect seal, you may notice the engine produces slightly more power.) And for an engine (valves) that's been in use for some time, the valves should be set at the lesser clearance because the valve faces and seats are already worn into each other (broke-in).

It's also important that the end of the valve stem is perfectly flat. This will allow for proper valve adjustment and valve action, especially in an OHV engine with rocker arms.

By the way - I get a lot of engines in my shop that need a valve job performed. Many other small engine repair shops will ignore the valves (or they're not trained to perform professional valve jobs) and assume the hard-starting problem is elsewhere with the engine.

If they're not burnt, then chances are, the valves and seats become warped from the block being heated under normal use after it was new and the metal "takes shape." Aluminum blocks (and heads) are worse than cast iron blocks (and heads). This happens with small engines as well as automotive engines. The block will actually deform a few thousands of an inch, moving the valves off the seats slightly, causing them to leak. Sometimes the cylinder wall(s) will deform a few thousands of an inch, too. Once the "seasoned" block or head takes shape, they won't warp any more. If the valves are leaking, then the valves and seats will need to be recut or reground so they're be in perfect alignment with each other and perpendicular with the guides.

To test for leaking valves, with the cylinder head removed and the piston at TDC on the compression stroke and both valves fully closed, spray WD-40 or an equivalent light liquid around each valve and then apply [150± psi] compressed air with a rag wrapped around the air nozzle through the exhaust and intake ports. Be sure to place the nozzle with the rag snug against the ports so full pressure will be against the valves. If bubbles form around the valves when applying the air pressure, this means the valves are leaking and a professional valve job is required.

And Remember... (added paragraph below on 7/13/14)

Rather if it's for competition pulling or for general yard and garden use, any fresh-built engine needs to fully break-in. Rings break-in quickly. But the valve faces needs to wear into the seats to seal in the compression 100%. The harder material the valves are made of, the longer it takes for them to "seat." Some pullers tell me that the engines I built for them run better every time they pull them. I remember a few years ago when I performed a valve job on my truck engine. It ran good, but I noticed it produced a little more power after 1,000 or so miles. This is because the valve faces wore into the seats, forming a perfect seal. So just to let you know, a fresh-built engine will not produce full power the first few times it's ran.

Just cleaning the valves and lapping them in, and then assume the engine will run fine for many years without problems is definitely not how a professional valve job is performed. Valve grinding compound (which is available at virtually any auto parts store) is not meant for "grinding valves". I realize it reads on the label: "Valve Grinding Compound," but this is wrong because it doesn't grind valves (or seats) whatsoever. A valve seat cutter/grinder and valve face grinding machine is meant to do this. The valve lapping compound is actually used to create a rough surface on the valve face and seat so they'll wear into each other as they break in, forming a perfect seal to keep the valves from leaking out compression.

Remember, when/if you have a repair shop perform a valve job, be sure to ask them how it's done. In other words, test their knowledge. If they say that the valves be removed, cleaned up, lapped in and then set the clearance, this is not the correct way to do it. Due to normal engine heat and "twisting" of the engine block (which is normal and happens to all flathead engines and OHV cylinder heads), valve heads become warped. New engine blocks (or cylinder head on OHV engines) rather it be cast iron or aluminum, will sometimes become "distorted" (bend and twist) a few thousands of an inch when it gets hot from normal use. The valves will become warped to match the warped block (or head). Therefore, to prevent loss of valuable compression and engine power, the valve faces will need to be reground in a valve grinding machine and the seats recut or reground with a valve seat cutter or grinder to put everything back in correct alignment. The head will literally move a few thousands of an inch offcenter of the valve stem. Therefore, the valve faces must be reground in a valve grinding machine, or if a valve is severely burnt, it should be replaced. And again, due to normal engine heat, the valve seats will literally move a few thousands of an inch offcenter of the valve guide. Therefore, the seats must be reground with a seat grinder or cutter so the valve faces will seal 360° around the seats.

Valves can leak! For example, if fuel sprays out of the carburetor on a twin cylinder engine when it's running at fast speed, then the following causes are...

  1. The hole in the main jet of the carburetor was mistakenly enlarged when cleaning because it was clogged with debris.
    • Solution: Install the correct size main jet or another known good carburetor.
  2. Inadequate valve to lifter clearance. The intake valves will not close in time to trap the air/fuel mixture in the combustion chamber, blowing some of it back through the carburetor. This happens a lot on twin cylinder engines as the valve faces wear into the seats.
    • Solution: A professional valve job needs to be performed. And then set the valves at .008" for the intake and .010" for the exhaust.
  3. But if a valve isn't opening or opening very little when the engine is cranked over, then chances are, a lobe on the camshaft is wore down. This happens when water gets in the crankcase and over time, condensation attaches itself to the base of the lifter, rusting and pitting it. While the engine is running, the rusted and pitted lifter wears (or grinds) the lobe until it's wore down or "rounded." This sort of thing will also prevent a single cylinder engine from revving up.
    • Solution: Install a good, unworn camshaft and good , unworn lifters. FYI - If the cam with the worn lobe has a good points lobe, good gear teeth and isn't cracked, damaged or worn in any other way, welding can be built up on both lobes, then reground to make a high-performance cam.

About Lead In Gas -

Lead in gas was actually meant for older automotive engines (pre-1970) because they had soft cast iron valve seats. The cylinder heads were made of cast iron and the seats were cut or ground directly in the head with no inserts. These seats was not heat-treated and would wear when no lead is present in gas. However, the later model automobile engine valve seats (1971-present) are heat-treated and last a lot longer. The seats were still cut or ground in the [cast iron] heads, but are heat-treated. The aluminum automotive heads have heat-treated steel inserts for valve seats. And virtually ALL small engine valve seats come from the factory heat-treated. They are steel inserts, and rarely wear when no lead is present in gas.


How to Perform a Professional Valve Job - Top of page

First of all, to gain more power and torque from virtually any flathead single or twin cylinder engine, perform a professional valve job and the valve clearances will need to be increased. Resurface the cylinder heads on a flat sanding disc to insure proper head gasket sealing. Nothing else may be needed to be done to the engine, except for perhaps a professional tune up. Many twin cylinder engines have inadequate valve clearances and this robs the engine of proper operation and valuable power. Perform a professional valve job, and set the clearances (between the valve stems and lifters) at .010" for the intake and .014" for the exhaust. After increasing the valve clearances, the engine will start quicker, idle better and produce more power at low and high rpm.

To do a poor quality valve job, some people will remove the valves, clean them thoroughly and then use valve grinding (lapping) compound to reseal them to the seats and then if they think of it, reset the valve clearances. Doing this might help an engine run better, but it's not how to perform a professional and/or performance valve job so the engine will start quicker, idle smoothly, accelerate without hesitation, and produce full power at higher rpms.

The tools that's required to perform a professional valve job are as follows:

To perform a professional valve job correctly the first time so the engine will run better:

  1. First rotate the crankshaft until the piston is at top dead center (TDC) on the compression stroke. Or, rotate the camshaft (if the crank is out of the block) until both valves are fully closed. If it's a twin cylinder engine, do this for each cylinder.
  2. After removing the crankcase breather, remove the valves using a valve spring compressor tool. Be sure not to lose the keepers! Store the valve components in a container so nothing will be misplaced! If you don't have a valve spring compressor tool, two medium size flat screwdrivers can be used to compress the spring and then have someone else remove and install the keepers. I had to do this when I first started working on engines. Then I found that a valve spring compressor makes it a lot easier.
  3. Valve Spring Compressor ToolRemove the valves, clean all the parts, and use a wire wheel to clean the carbon from the valves. They may need to be sandblasted if the carbon is really hard to remove.
  4. Inspect the valve face for wear, and measure the stem diameter for wear.
  5. Check the valve guides for wear. Most of the time, the exhaust guide will wear more than the intake due to carbon deposits. The maximum wear limit on the 7hp and 8hp Kohler engines is .005" for the intake,.007" for the exhaust. And on the 10hp, 12hp, 14hp and 16hp Kohler engines, it's .006" for the intake and .008" for the exhaust. If the guides are worn, install new guides or have a new thin-wall bronze liner installed. An excessively worn intake and/or exhaust valve guide will cause an engine to make a popping sound out the intake or exhaust while it is running.
  6. If they're not burnt, bent or badly warped, then used valves can be refaced on a valve grinding machine at an automotive engine machine shop. But if they're damaged or excessively worn in any way, they must be replaced. If the valves are reusable, grind the intake and exhaust valve(s) and seat(s) at 45º/46º angles (Kohler engines), respectively. The reason there's a 1º difference is because as the valve and seat wear together, they'll form a perfect 31-½° angle (intake, for high-performance use) or 45-½° angle (intake and exhaust) leak-proof seal. As the valves/seats break-in, the engine will produce slightly more power because they'll be retaining full compression within the combustion chamber. In an average engine, it takes about 2 hours of operation for the valves to fully seat. When dyno-testing an engine, make sure it has at least 2 hours of break-in time on it.
    NOTE: All of Kohler's valves come from the factory with a face angle of 45º, and the seat angles are ground at 46º. And there's no need for the valve seat contact area to be midway of the face on the valve. (This is determined by lapping in the valves.) The engine will actually breath better at higher rpms if the seat contact area is closer to the edge of the valve face.
    If a valve stem is bent, chances are, it can be straightened and the valve can be reused. I repair bent valves in my big metal lathe with success. Here's how to do it:
    1. First of all, if there's a crack in the valve stem, it must be replaced, especially when used in an OHV engine. It's best to inspect the stem for a hairline crack with a strong magnifying glass or better yet, a powerful microscope. Do not attempt to weld up a cracked valve stem, especially an exhaust valve and after straightening it! It will break later!
    2. If the valve appears to be reusable, chuck the valve in a [big] metal lathe with the bent part of the stem flush with the end of the chuck jaws.
    3. Turn the lathe on slow and scribe a mark on the margin of the valve head to indicate the bent side.
    4. Rotate the lathe chuck by hand so the bent side of the valve head (scribe mark) is facing upward.
    5. If it's an intake valve, being most of them are made of mild steel, it can be straightened cold, with the exception of a Stellite valve. But if it's a Stellite or an ordinary exhaust valve, use an acetylene torch to lightly heat the valve stem. Don't attempt to straighten a Stellite or an exhaust valve cold. Due to the hardness and brittleness of the steel, the stem could break either when straightening it or later in the engine!
    6. lightly strike the valve head with a brass hammer to straighten the stem.
    7. Turn the lathe on slow again to check the straightness of the stem with the sensor button of a dial indicator against the margin of the valve head.
    8. If it's still slightly bent, lightly heat the stem (again) and use the hammer again.
    9. Repeat this process until the valve head has less than .003" of run-out.
    10. After the valve is straight, allow it to air-cool (don't dip it in water!), and then reground the valve face on a valve grinding machine so it'll be perfectly perpendicular with the center line of the valve stem and so the valve face will seal 360° with the seat.
    11. If you have doubts that a valve stem will straighten properly, then perhaps it should be replaced. If a valve is obsolete, chances are, a valve from another make and model of engine can be machined to match the overall dimensions of the original/obsolete valve.
  7. After grinding the valves and seats, and with the governor assembly, lifters, camshaft, crankshaft, piston/rod and bearing plate all properly installed, and with the piston at TDC on the compression stroke (this when the base circle of the cam lobes are on top and both valves are fully closed), install the valves, springs, retainers and keepers and then check for proper valve lash (the clearance or gap between the valve stem and lifter). Set the valve clearances as follows for Kohler's K-series and Magnum single cylinder engines:
    • Always set the valve clearance when an engine is cold. Because metal expands when hot and shrinks when cold. On a fresh valve job, set the clearance on the maximum specs to allow for the valve face and seat to wear into each other. And then after approximately 25 hours of running time, recheck the clearances and set them at on the minimum. (If the gap haven't already minimized.)
    • For the 7hp and 8hp engines, the clearances are: .006"-.008" for the intake and .017"- .019" for the exhaust. Adjustment is made by lightly grinding the end of the valve stems. Be careful not to grind too much! This is the same way Briggs & Stratton and Tecumseh flathead engines valves are adjusted.
    • Feeler GaugeUse steel feeler gauges to set the valve clearances. For the 10-16hp engines, for ordinary yard use, the valve clearances are: .008"-.010" for the intake and .017"-.019" for the exhaust with the piston at TDC on the compression stroke. This is when both valves are fully closed. For competition pulling, set the valve clearances at .010" for the intake and .014" for the exhaust.
  8. When checking the valve lash on any engine, the piston in the cylinder for the valves that you're checking (on multiple cylinder engines) must be at top dead center (TDC) on the compression stroke. This places the lifters on the base circle of the cam lobes. The reason there's a valve lash is so the valves can fully close, sealing in the compressed air/fuel mixture in the combustion chamber. Too little lash, and some of the compression will escape through one or both valves, and in over time, a valve may burn. Too much lash, and the valves won't open fully, preventing the engine from producing full power.
  9. To adjust the valves, remove the valve cover, and then rotate the crankshaft by hand until both valves are fully closed with the piston at TDC on the compression stroke. If one valve opens slightly and the other closes slightly and vice-versa while rotating the crankshaft back and forth, then the piston is on the exhaust stroke and the crankshaft needs to be rotated one full turn (180°). This will guarantee that both valves are fully closed so accurate valve adjustments can be made.
  10. Valve adjustment is made with the engine cold, with a flat feeler gauge and on the 10-16hp engines, with the lifter held in place with a slender 1/2" open-end wrench and turning the adjuster screw in the lifter with a 7/16" open-end wrench. When checking valve clearance, always have the piston at the TDC position on the compression stroke. And make sure the ends of the lifters and valve stems are ground square for proper adjustment.
  11. After making the proper lash adjustments, remove the valves, and apply a small quantity of valve grinding (lapping) compound on each valve face and then Valve Lapping Tooluse a valve lapping tool to lap the valves in the seats (use this tool to rotate each valve back and forth with both hands) until the "grinding sound" goes away. This process is important. It seals the valves to the seats.
  12. After lapping in the valves, remove the valves and thoroughly clean the compound material from the valves and seats and then inspect the valve faces to see if the compound made full contact of 360º around each valve face and seat. If it didn't, then the valve is warped, or the face or seat wasn't ground correctly and will need to be re-done.
  13. When installing the valves, lubricate the stems with motor oil. After compressing a valve spring, apply a small quantity of grease (chassis lub) on each keeper and on the end of a flat screwdriver, and then place the keeper on the screwdriver and use the screwdriver to place the keeper on the stem. (The grease will hold the keepers to the stem until the spring can be released.)
  14. Rotate the crankshaft and observe the opening and closing of each valve. And take notice that the springs don't coil-bind. (Coil-bind is when the coils of the spring actually touch each other when the cam is at full lift. This may happen only with a high-lift cam.) If the springs do coil-bind, it may be necessary to remove the springs and grind some of the end off of each spring or acquire a different set of springs.
  15. Reinstall the crankcase breather using new gaskets, and that's it! Return To Previous Web Page.

What Are Valve Rotators and Why Are They Used?

For a non-pulling engine, valve rotators help prevent valves from burning by rotating the valve slightly as it opens to scrape away any carbon deposits from the valve face and seat. If an engine didn't come with valve rotators (most early Kohler engines didn't), they can be installed instead of the stamped steel non-rotator retainers. Many automotive engines use valve rotators, too. A rotator should be used with the exhaust valve because that's the one where the carbon exits the combustion chamber, and is optional for use with the intake valve. Rotators can be used in any 6¼hp-16hp Kohler engine. It's important that a rotator be used with the 1-9/16" uncompressed height OEM valve spring to prevent coil bind at full valve lift, which may result in cam breakage. Stamped or machined steel retainers require a 1-3/4" uncompressed height OEM spring. If the shorter 1-9/16" spring is used with a non-rotator retainer, the valve(s) may float, and/or the keepers may become dislodged from the valve stem at higher rpms. Although valve rotators are extremely strong, competition pulling engines don't require them because they don't run long enough for carbon to build up in the combustion chamber.

How to Perform a Professional Valve Job on a Twin Cylinder Flathead B&S or Kohler engine -

To gain more power and torque from virtually any flathead two or twin cylinder engine, perform a professional valve job and the valve clearances will need to be increased. Resurface the cylinder heads on a flat sanding disc to insure proper head gasket sealing. Nothing else may be needed to be done to the engine, except for perhaps a professional tune up. Many twin cylinder engines have inadequate valve clearances and this robs the engine of proper operation and valuable power. Perform a professional valve job, and set the clearances (between the valve stems and lifters) at .010" for the intake and .014" for the exhaust. After increasing the valve clearances, the engine will start quicker, idle better and produce more power at low and high rpm.

To perform a professional valve job on a twin cylinder flathead B&S or Kohler engine, the parts that will be needed are: two head gaskets, two crankcase breather gaskets, intake manifold mounting gaskets and valve stem seals (for intake valves only). New valve guides, especially for the exhaust valves, may also be needed. But that's to be determined once the valves are removed. A quality-made valve spring compressor tool is required to remove and reinstall the valves. The valve faces and valve seats angles are to be reground or recut at 45° (intake valve face for Kohler), 30° (intake valve face for B&S) and 46° (intake and exhaust seats for Kohler and exhaust seat only for B&S), 31° (intake seat for B&S), respectively. If you can't do this yourself, a local automotive machine shop can do it for you. You'll need to take the engine or tractor to the shop to have the valve seats reground or recut. Make sure they're reground or recut at the proper angle, too! And it'll be a good idea to have both cylinder heads resurfaced on a flat sanding disc to ensure proper head gasket sealing. The head bolts can be reused. They rarely go bad.

Advertisement: FYI - Due to new EPA rules and regulations, Kohler (and many other small engine manufacturers) are phasing out many parts for their flathead and cast iron block engines. But the parts in question may be available in aftermarket.
If you need any of the parts listed below Ê, please contact A-1 Miller's Performance Enterprises | 1501 W. Old Plank Rd. | Columbia, MO 65203-9136 USA | Phone: 1-573-256-0313 (home/shop) | 1-573-881-7229 (cell/text). Please call Monday-Friday (except Holidays), 9am to 5pm, Central time zone. If no answer, please try again later. (When speaking with Brian, please be patient because I stutter.) Fax: 1-573-449-7347. E-mail: pullingtractor@aol.com. Send a message with Yahoo Messenger: | Directions to our shop | Yahoo! Maps, 1501 W. Old Plank Rd., Columbia, MO | 1501 West Old Plank Road, Columbia, MO - Google Maps or Map of 1501 West Old Plank Road, Columbia, MO by MapQuest. Click here for more parts and services. | NOTE: To place an order, please call or send an email with a list and description of the parts or services you need. Because as of right now, we're not set up to accept orders through our web sites online. Due to the rising cost of... everything, prices are subject to change.
Valves for Kohler engine models KT90/KT91. 15/16" head diameter. Not available in aftermarket.
  • Intake. OEM Kohler part # 220008-S. $29.00 each, plus shipping & handling.
  • Exhaust. OEM Kohler part # 220009-S. $38.15 each, plus shipping & handling.
Intake Valves for Kohler K-series and Magnum engine models K141 (6¼hp), K160 (6.6hp), K161 (7hp) and K181/M8 (8hp) flathead cast iron block engines. Dimensions: 1-3/8" head diameter; 4.065" overall length; .309" stem diameter; 45° face angle.
  • Ordinary Valves. Kohler part # 230008-S.
    • Aftermarket. $16.00 each, plus shipping & handling.
    • OEM Kohler valve. $30.00 each, plus shipping & handling.
  • Stellite Valve. OEM Kohler part # 230582-S. $73.00 each, plus shipping & handling.
  • Used Refaced OEM Kohler Valve. $10.00 each, plus shipping & handling. (When available.)
    • Grind 30° face angle on intake valve: $5.00 extra. (Seat must be recut or reground to 31° to match valve face angle.)

Exhaust Valves for Kohler K-series and Magnum engine models K141 (6¼hp), K160 (6.6hp), K161 (7hp) and K181/M8 (8hp) flathead cast iron block engines. Dimensions: 1-1/8" head diameter; 4.065" overall length; .309" stem diameter; 45° face angle.

  • Ordinary Valves. Kohler part # 230710.
    • Aftermarket. $20.00 each, plus shipping & handling.
    • OEM Kohler valve. $35.00 each, plus shipping & handling.
  • Stellite Valve. OEM Kohler part # 230027-S. $74.00 each, plus shipping & handling.
  • Used Refaced Kohler Valve. $5.00 each, plus shipping & handling. (When available.)
Intake Valves for Kohler K-series and Magnum engine models K241/M10 (10hp), K301/M12 (12hp), K321/M14 (14hp) and K341/M16 (16hp) flatheads, and models K482, K532 and K582. Dimensions: 1-3/8" head diameter; 4.640" overall length; .3095" stem diameter; 45° face angle.
  • Ordinary Valves. Kohler part # 235008-S.
    • Aftermarket. $7.50 each, plus shipping & handling.
    • OEM Kohler part. $40.00 each, plus shipping & handling.
  • Stellite Valves. Kohler part # 235582-S.
    • Aftermarket. $26.00 each, plus shipping & handling.
    • OEM Kohler part. $81.00 each, plus shipping & handling.
  • Used Refaced 1-3/8" OEM Kohler Intake Valve. $10.00 each, plus shipping & handling. (When available.)
    • Grind 30° face angle on intake valve. $5.00 extra. (Seat must be recut or reground to 31° angle to match valve face.)

Exhaust Valves for Kohler K-series and Magnum engine models K241/M10 (10hp), K301/M12 (12hp), K321/M14 (14hp) and K341/M16 (16hp) flatheads, and models K482, K532 and K582. Dimensions: 1-1/8" or 1-3/8" head diameter; 4.065" overall length; .309" stem diameter; 45° face angle.

  • 1-1/8" Ordinary Valves for Kohler K-series and Magnum engine models K241/M10 (10hp), K301/M12 (12hp), K321/M14 (14hp) and K341/M16 (16hp) flatheads, and models K482, K532 and K582. Kohler part # 235826-S.
    • Aftermarket. $15.00 each, plus shipping & handling.
    • OEM Kohler part. $35.00 each, plus shipping & handling.
  • 1-1/8" Stellite Valves for Kohler K-series and Magnum engine models K241/M10 (10hp), K301/M12 (12hp), early K321, M14 (14hp) and models K482, K532 and K582. (For K582 before serial # 9165451.) Kohler part # 235838-S.
    • Aftermarket. $26.00 each, plus shipping & handling.
    • OEM Kohler part. $57.00 each, plus shipping & handling.
    • OEM Kohler part # 48 016 01-S. $67.00 each, plus shipping & handling.
  • 1-3/8" Stellite Valves for later K321, M14 (14hp), K341/M16 (16hp), K532 and K582 (For K582 after serial # 9165450). Kohler part # 237672-S.
    • Aftermarket. $26.00 each, plus shipping & handling.
    • OEM Kohler part. $57.00 each, plus shipping & handling.
  • Used Refaced 1-1/8" or 1-3/8" OEM Kohler Exhaust Valves. $5.00 each, plus shipping & handling. (When available.)
New Intake Valve for Kohler engine model K361 (18hp OHV). Dimensions: 1.437" head diameter; 4.175" overall length; .3095" stem diameter; 45° face angle. OEM Kohler part # 45 017 01-S.
  • $126.10 each, plus shipping & handling.

NOTE: New exhaust valve and for Kohler engine model K361 (18hp OHV) (part # 45 016 02-S) is no longer available from Kohler, in aftermarket or from any other source. If you're lucky, maybe one can be found in a dealer's old stock. Dimensions for making exhaust valve: head diameter: 1.437"; overall length: 4.158"; stem diameter: .309"; face angle: 45°. (The OEM manufacturers are phasing out many parts for flathead engines due to EPA smog emissions. But some parts may still be available in aftermarket.)

Exhaust Valve for Kohler engine models KT17, KT17II, MV16, M18 and MV18. Used on MV16, M18, MV18 engines with serial number 1815600656 and later. Dimensions: 1.371" head diameter; 3.663" overall length; .311" stem diameter; 30° face angle. Can also be used as the intake valve on engines with a 46° seat with seat recut or reground to a 31° angle.
  • Aftermarket. Replaces Kohler part # 52 016 02-S. (Discontinued from Kohler.) $14.00 each, plus shipping & handling.

Exhaust Valve for Kohler engine models KT17, KT17II, MV16, M18 and MV18 engines. Used on MV16, M18, MV18 engines with serial number 1816500646 and earlier. Dimensions: 1.373" head diameter; 3.641" overall length; .3075" stem diameter; 45° face angle. Can also be used as the intake valve on engines with a 31° seat with seat recut or reground to a 46° angle.

  • OEM Kohler part # 52 016 05-S. $46.50 each, plus shipping & handling.

NOTE: Valve dimensions for the KT-series and Magnum twin cylinder flathead engines are somewhat confusing. Kohler is no help on this matter whatsoever. They give their dealers very limited detailed information on all of their parts. So I have to do a lot of research on Kohler parts myself. Anyway, new Kohler engine models MV16, M18 and MV18 intake valves (part #'s 52 017 07-S, 52 017 08-S) are no longer available. And new Kohler engine models KT17, KT17II, KT19, KT19II, KT21, M20 and MV20 intake valves (part #'s 52 017 01-S, 52 017 02-S, 52 017 03-S) and exhaust valves (part #'s 52 016 01-S, 52 016 02-S, 52 016 03-S) are also no longer available. (The KT19, KT19II, M20 and MV20 intake and exhaust valve dimensions are: 1.375" head diameter x 3.900" overall length.) If your original valves are not severely worn, warped, bent or burnt, the valve face can be reground (to either a 30° or 45° angle) and the valve can be reused. If they're bent, they may be straightened, reground and reused. (The OEM manufacturers are phasing out many parts for flathead engines due to EPA smog emissions. But some parts may still be available in aftermarket.)

Exhaust Valve Seat Insert for 1.125" diameter valve. Fits Kohler engine models K141, K160, K161, K181/M8, K241/M10, K301/M12 and early K321 (used with spec number suffix "A"). Dimensions: 1.125" i.d. x 1.250" o.d. OEM Kohler part # 230170-S.
  • $33.50 each, plus shipping & handling.

Intake and Exhaust Valve Seat Insert for 1.375" diameter valves. Fits Kohler engine models K321 (not used after spec number suffix "A"), all M14 and all K341/M16. Dimensions: 1.250" i.d. x 1.500" o.d. OEM Kohler part # 230265-S.

  • $51.60 each, plus shipping & handling.
è Valves for other makes and models of small engines are also available. NOTE: Valves for Kohler twin cylinder flathead engine models M20 and MV20 are no longer available from Kohler. However, the aftermarket valves are back-ordered due to a tsunami, which wiped out several factories in China or Taiwan. They're rebuilding the factories now, but it'll be some time before they'll have valves (and other parts) available.
Stock (centered) Cast Iron Valve Guide for Kohler K-series and Magnum engine models K141 (6¼hp), K160 (6.6hp), K161 (7hp) and K181/M8 (8hp). Dimensions: .310" i.d. x .5645" o.d. x 1.686" overall length. Note: After installation, guide may need to be enlarged with a 5/16" reamer for proper valve stem clearance. And before installing valve, apply clean motor oil on valve stem to provide lubrication of the guide and stem. Kohler part # 230007-S.
  • Aftermarket. $6.00 each, plus shipping & handling.
  • OEM Kohler part. $13.70 each, plus shipping & handling.

Stock (centered) Cast Iron Valve Guide for Kohler K-series and Magnum engine models K241/M10 (10hp), K301/M12 (12hp), K321/M14 (14hp), K341/M16 (16hp), K482, K532 and K582. Dimensions: .310" i.d. x .629" o.d. x 2.135" overall length. Note: After installation, guide may need to be enlarged with a 5/16" reamer for proper valve stem clearance. And before installing valve, apply clean motor oil on valve stem to provide lubrication of the guide and stem. Kohler part # 235007-S.

  • Aftermarket. $10.00 each, plus shipping & handling.
  • OEM Kohler part. $16.45 each, plus shipping & handling.

Stock (centered) Cast Iron Valve Guide for Kohler engine model K361 (18hp OHV) cylinder head. Note: After installation, guide may need to be enlarged with a 5/16" reamer for proper valve stem clearance. And before installing valve, apply clean motor oil on valve stem to provide lubrication of the guide and stem.

  • Intake valve guide. OEM Kohler part # 45 316 02-S. $13.15 each, plus shipping & handling.
  • New exhaust valve guide (part # 45 755 11-S) is no longer available. (The OEM manufacturers are phasing out many parts for cast iron block engines due to EPA smog emissions. But some parts may still be available in aftermarket.)

Stock (centered) Cast Iron Valve Guide for KT-series and Magnum flathead twin cylinder Kohler and Magnum engine models MV16, KT17, KT17II, KT19, KT19II, M18, MV18, M20 and MV20. Dimensions: .305 i.d. x .500" reduced o.d. (for seal) x .563" o.d. x 1.378" overall length. Note: After installation, guide may need to be enlarged with a 5/16" reamer for proper valve stem clearance. And before installing valve, apply clean motor oil on valve stem to provide lubrication of the guide and stem. Kohler part # 52 316 08-S.

  • Aftermarket. $10.50 each, plus shipping & handling.
  • OEM Kohler part. $12.75 each, plus shipping & handling.
  • NOTE: To replace the valve guides in the MV16, KT17, KT17II, KT19, KT19II, M18, MV18, M20 or MV20 engines with engine fully assembled, first remove the springs, retainers and valves, then break off the protruding end of the guide in the valve spring compartment with a hammer and chisel, and then drive out the remaining portion of the guide into the spring compartment. Install new guides by driving them in until flush with the surface of the port. Then ream the guides so the valve stems will have proper clearance.
Valve Guide Removal and Installation Tool. Use with a big hammer to remove (drive out) and install valve guides. Can be used for OEM Kohler and aftermarket offset valve guides. .300" diameter pilot. Machined from a 1/2" diameter x 5" overall length grade 8 bolt.
  • A-1 Miller part. $10.00 each, plus shipping & handling.
Straight Flute High Speed Steel Precision Chucking Reamers. Perfect size to ream out new valve guides to OEM Kohler specs or installing Chevy valves in Kohler engines. Provides proper clearance. Will not allow the valve stems to be too loose or too tight.
  • 5/16" Reamer. Dimensions: diameter of cutter: .310", flute length: 1-1/2", overall length: 6". $12.00 each, plus shipping & handling.
  • 11/32" Reamer. Dimensions: diameter of cutter: .340", flute length: 1-1/2", overall length: 6". $12.50 each, plus shipping & handling.
Valve Stem Seals for Kohler engine model K361 (18hp OHV), and KT-series and Magnum flathead twin cylinder engine models MV16, KT17, KT17II, KT19, KT19II, M18, MV18, M20 and MV20. Comes with complete gasket sets for these engines. NOTE: A seal is used on the intake valves to prevent crankcase oil from being drawn into combustion chamber, which could cause the engine to smoke upon start up. And apply clean motor oil on valve stem before inserting valve through seal to provide lubrication of the stem, guide and seal. Dimensions: 5/16" i.d. (stem) x .500" i.d. (guide) x .600" o.d.
  • Aftermarket. Teflon rubber w/metal cap. $3.00 each, plus shipping & handling.
  • Aftermarket. Teflon rubber w/metal clamp. $4.00 each, plus shipping & handling.
  • OEM Kohler part #'s 45 032 01-S, 52 032 13-S. Silicone rubber w/metal clamp. $18.00 each, plus shipping & handling.

Valve Stem Seal for Kohler engine models CH18-CH1000, CV17-CV1000, ECH630-ECH749, ECV730-ECV980, KT715-KT745, PCH680-PCH740, PCV680-PCV740, ZT710-ZT740. Silicone rubber w/metal clamp. NOTE: In an OHV engine with worn or dry-rotted valve stem seals, when the engine is shut down and allowed to sit for a period of time, oil seeps down past the opening in the seal into the combustion chamber. As a result, as soon as the engine is started, the oil is burned, and no more smoke until the engine is shut down, and the process repeats itself. Also, the seeping oil will cause an excess of carbon deposits to build up under the valve head(s), preventing a full flow of air to enter (or exit) the combustion chamber, causing the engine to lose power at higher rpms. And apply clean motor oil on valve stem before inserting valve through seal to provide lubrication of the stem, guide and seal. OEM Kohler part #'s 25 032 14-S, 66 032 05-S.

  • $5.85 each, plus shipping & handling.
If you need something that's not listed here, please contact me and I'll see if I can get it for a reasonable price. Please contact me if you're interested in any of the above È parts or items.


How to Repair a Loose Valve Seat in an Aluminum Flathead Block Engine - Top of page

below Ê is the professional way of doing it.

  1. The valve will need to be removed from the block or head.
  2. The loose seat will need to be peened back in place with a 1/4" diameter blunt punch and medium size hammer or the ball end of a medium size ball-peen hammer. "Peening" is when the aluminum is "pounded" 360° around the seat so it will remain tight. Be sure to stagger the punches to begin with so the seat will be centered and won't sit crooked in the block or head.
  3. Perform a professional valve job by using a valve seat cutter and valve refacer to true up both the seat and valve face. Recut both seats and grind both valve faces, set the valve clearances to specs (to make sure the other valve seals good, too) and then lap the valves in so they'll seal perfectly upon break-in.

The reason a valve seat loosens in an aluminum engine block or cylinder head is because either the factory didn't press the metal tight enough around the seat or the aluminum expanded just enough with engine heat causing the seat to loosen. After the seat is securely tightened back in place, it shouldn't give any more trouble.

NOTE: Sometimes the seat can loosen so much, the counterbore where the seat rests will become enlarged. In fact, it can be too large to peen the seat back in place. When this happens, the counterbore will need to be bored for an oversized outside diameter seat. It takes a reputable machine shop/business to perform this type of repair.


How to Repair A Loose Valve Seat and Worn or Loose Valve Guides in the K361 18hp OHV Cylinder Head - Top of page

The Kohler engine model K361 18hp single cylinder cast iron block OHV cylinder head is notorious for one or both valve seats and/or one or both valve guides becoming loose. This also happens with certain OHV (OverHead Valve) small engine (and certain automotive) cylinder heads. But on the K361 head, what causes a seat to loosen is the aluminum was molded around the steel seats with a "tongue and groove" design to secure the seat in place. Due to normal (or perhaps excessive) engine heat, sometimes the two metals (aluminum head and steel seat) will separate from each other, allowing the seat to loosen.

First of all, before attempting to repair a loose seat, if the valve guide for the seat in question is worn (inside) or loose in it's bore, it will need to be repaired first.

How to Repair a Loose Valve Seat:

  1. Acquire a quality bronze valve seat insert with the outside diameter slightly larger than the counterbore of the old seat, but the same approximate inside diameter so the original size valve can be reused. FYI - Bronze is highly recommended because it grips aluminum better than any steel valve seat. Plus, bronze is harder than cast iron.
  2. With the head set up in a valve seat machine or on the table of a milling machine with the right kind of tooling, cut into the head to remove the old seat.
  3. Bore the counterbore for the new seat .005" smaller than the outside diameter of the new seat and machine the depth of the counterbore the same height as the new seat. The .005" interference fit is the standard for a perfect press fit regarding a valve seat insert.
  4. Chamfer or bevel the lower outer edge of the new seat in a small metal lathe for easier installation into the counterbore.
  5. Apply high strength sleeve retainer on the circumference of the seat and/or in the counterbore.
  6. Press or drive the new seat perpendicular into the counterbore until it bottoms out.
  7. The seat angle is then cut or ground to match the angle on the valve face and be perpendicular with the centerline of the valve guide.
  8. NOTE - If a small "stress crack" forms between the valves after the seat is installed, this will hurt absolutely nothing because the crack only goes down about half the depth of the installed seat. And besides, the engine is not water-cooled.
  9. Valve Clearances:
    • Set the intake valve clearance at .008" for a fresh valve job, and .005" for a valve that's worn into the seat (after 5 hours of break-in).
    • Set the exhaust valve clearance at .012" for a fresh valve job, and .010" for a valve that's worn into the seat (after 5 hours of break-in).

By the way - the upper K361 valve components receive plenty of crankcase lubrication at all engine speeds. Because at idle speed, the valves, rocker arms, pushrods, etc., don't move or work that fast, which produce very little friction between the moving parts, so they require very little oil. And at higher or normal running speed (3,600 rpm), the upper valve parts receive plenty of crankcase lubrication.

Advertisement:
If you need your K361 cylinder head repaired or parts, please contact A-1 Miller's Performance Enterprises | 1501 W. Old Plank Rd. | Columbia, MO 65203-9136 USA | Phone: 1-573-256-0313 (home/shop) | 1-573-881-7229 (cell/text). Please call Monday-Friday (except Holidays), 9am to 5pm, Central time zone. If no answer, please try again later. (When speaking with Brian, please be patient because I stutter.) Fax: 1-573-449-7347. E-mail: pullingtractor@aol.com. Send a message with Yahoo Messenger: | Directions to our shop | Yahoo! Maps, 1501 W. Old Plank Rd., Columbia, MO | 1501 West Old Plank Road, Columbia, MO - Google Maps or Map of 1501 West Old Plank Road, Columbia, MO by MapQuest. Click here for more parts and services. | NOTE: To place an order, please call or send an email with a list and description of the parts or services you need. Because as of right now, we're not set up to accept orders through our web sites online. Due to the rising cost of... everything, prices are subject to change.

Kohler model K361 (18hp OHV) Cylinder Head Repairs - NOTE: I have another automotive machine shop here in Columbia repair my customer's K361 heads because I don't have the required equipment and tooling to perform the repairs. Sometimes they get busy with a lot of other customer's repairs and if you want to send your head to me, it may be some time before they will have it repaired. I can't say when they will have it repaired, but they perform professional, high quality work & they guarantee their repairs.

  • Repair loose valve seat. (Install bronze valve seat. FYI - Bronze grips aluminum better than steel, and it's harder than cast iron. Also, periodic valve adjustment may be needed with a bronze valve seat.) $50.00 each for parts and labor, plus return shipping and handing.
  • Repair worn inside of valve guide. $20.00 each for parts and labor, plus return shipping and handing.
  • Repair loose valve guide. $30.00 each for parts and labor, plus return shipping and handing.
  • Resurface all gasket mating surfaces. $20.00 labor, plus return shipping and handing.
  • Perform valve job to OEM specs (regrind two valve faces and seats), install valves, springs, retainers and keepers. $35.00 labor, plus return shipping & handling.

Complete engine rebuild gasket set w/oil seals for Kohler K-series model K361 (18hp) cast iron block single cylinder OHV engine. Includes oil seals. (The aftermarket set is actually less than individual OEM gaskets just to reinstall the head.) Kohler part # 45 755 06-S.

  • Aftermarket. $42.00 each, plus shipping & handling.
  • OEM Kohler part. $110.00 each, plus shipping & handling.

New Intake Valve for Kohler engine model K361 (18hp OHV). Dimensions: head diameter: 1.437"; overall length: 4.175"; stem diameter: .3095"; face angle: 45°. OEM Kohler part # 45 017 01-S.

  • $126.10 each, plus shipping & handling.

NOTE: New exhaust valve and for Kohler engine model K361 (18hp OHV) (part # 45 016 02-S) is no longer available from Kohler, in aftermarket or from any other source. If you're lucky, maybe one can be found in a dealer's old stock. Dimensions for making exhaust valve: head diameter: 1.437"; overall length: 4.158"; stem diameter: .309"; face angle: 45°. (The OEM manufacturers are phasing out many parts for flathead engines due to EPA smog emissions. But some parts may still be available in aftermarket.)

Intake Valve Guide for Kohler engine model K361 (18hp OHV) cylinder head. OEM Kohler part # 45 316 02-S.

  • $12.40 each, plus shipping & handling.

New exhaust valve guide (part # 45 755 11-S) is no longer available. (The OEM manufacturers are phasing out many parts for flathead engines due to EPA smog emissions. But some parts may still be available in aftermarket.)

About Installing Bigger Valves in the K361 (18hp) OHV Engine Cylinder Head -

On the K361's cylinder head, the stock valve head diameters are: intake - 1.438"; exhaust - 1.400". The exhaust valve is already plenty big enough, even for high rpms. But there's not that much room in the combustion chamber to install a bigger intake valve because a bigger seat would need to be installed first. The outside diameter of the seat is always larger than the diameter of the valve head. The biggest intake valve that can be installed would be about 1.5", which really wouldn't give the engine that much more performance. For more noticeable performance, the intake valve needs to be about 25-30% bigger than the exhaust valve, which would make it 1.68". And this is way too big for the K361 head.

Advertisement:
If you need any of the parts or services listed below Ê, please contact A-1 Miller's Performance Enterprises | 1501 W. Old Plank Rd. | Columbia, MO 65203-9136 USA | Phone: 1-573-256-0313 (home/shop) | 1-573-881-7229 (cell/text). Please call Monday-Friday (except Holidays), 9am to 5pm, Central time zone. If no answer, please try again later. (When speaking with Brian, please be patient because I stutter.) Fax: 1-573-449-7347. E-mail: pullingtractor@aol.com. Send a message with Yahoo Messenger: | Directions to our shop | Yahoo! Maps, 1501 W. Old Plank Rd., Columbia, MO | 1501 West Old Plank Road, Columbia, MO - Google Maps or Map of 1501 West Old Plank Road, Columbia, MO by MapQuest. Click here for more parts and services. | NOTE: To place an order, please call or send an email with a list and description of the parts or services you need. Because as of right now, we're not set up to accept orders through our web sites online. Due to the rising cost of... everything, prices are subject to change.
Cylinder head gasket for K90 (3.6hp), K91 (4hp) Kohler flathead engines. Approximately .050" compressed thickness; included in complete engine rebuild gasket set. Kohler part # 220124-S.
  • Aftermarket. $8.00 each, plus shipping & handling.
  • OEM Kohler part. $9.10 each, plus shipping & handling.
Cylinder head gasket for K141 (6¼hp), K160 (6.6hp), K161 (7hp) and K181/M8 (8hp) Kohler K-series and Magnum flathead engines. Approximately .050" compressed thickness; included in complete engine rebuild gasket set. Kohler part # 41 041 10-S.
  • Aftermarket. $6.50 each, plus shipping & handling.
  • OEM Kohler part. $9.10 each, plus shipping & handling.
Cylinder head gasket for 10hp, 12hp & 14hp K-series and Magnum flathead engines. Approximately .050" compressed thickness; included in complete engine rebuild gasket set. Kohler part # 47 041 15-S.
  • Aftermarket. $6.00 each, plus shipping & handling.
  • OEM Kohler part. $14.75 each, plus shipping & handling.
Cylinder head gasket for 16hp K-series and Magnum flathead engines. Approximately .050" compressed thickness; included in complete engine rebuild gasket set. Kohler part # 45 041 17-S.
  • Aftermarket. $10.50 each, plus shipping & handling.
  • OEM Kohler part. $14.80 each, plus shipping & handling.
Cylinder head gasket for 18hp K361 K-series OHV engine. Approximately .050" compressed thickness; included in complete engine rebuild gasket set. Kohler part # 45 052 02-S.
  • OEM Kohler part only. $21.50 each, plus shipping & handling.
Head gasket for MV16, KT17, KT17II, KT19, KT19II, M18, MV18, M20 & MV20 twin cylinder flathead Kohler engines. Kohler part # 52 041 20-S.
  • Aftermarket. $9.50 each, plus shipping & handling.
  • OEM Kohler part. $19.00 each, plus shipping & handling.
Prices below Ê are with the engine out of the engine, and on my work table.

Other Services include:

  • Grind used valve to OEM angle: $5.00 each, plus return shipping & handling.
  • Grind your [45°] intake valve at 30° angle and undercut head for more airflow. $17.00 labor each, plus return shipping & handling.
  • Grind seat in your block or OHV head to OEM angle or 30° angle: $5.00 labor each, plus return shipping & handling.
  • Perform valve job to OEM specs (grind two valve faces and seats), install valves in OEM [Kohler] block and set clearances: $25.00 labor, plus return shipping & handling..
  • Perform performance valve job on two stock valves and seats in OEM [Kohler] block for improved airflow: $40.00 labor, plus return shipping & handling.. Price includes grinding the exhaust valve & seat at 45°/46° angles, intake valve and seat at 30°/31° angles respectively and undercutting both valve heads.
  • Install oversize valves in OEM [Kohler] block: $150.00 - $200.00 (depending size of valves) labor, plus return shipping & handling. Price does not include any parts.
  • Install stock size valves in aftermarket [Kohler] block with small uncut valve pockets: $150.00 labor, plus return shipping & handling. Price does not include any parts.
  • Install oversize valves in aftermarket [Kohler] block with small uncut valve pockets: $200.00 labor, plus return shipping & handling. Price does not include any parts.
  • Port/polish intake and exhaust runners (OEM and aftermarket [Kohler] block with large ports): $75.00 labor, plus return shipping & handling.
  • Port/polish intake and exhaust runners (aftermarket [Kohler] block with small ports): $200.00 labor, plus return shipping & handling.
  • Install 1-3/8" exhaust valve in 10, 12 and older 14hp OEM Kohler block: $50.00 labor, plus return shipping & handling.
  • Install oversize valves, and port/polish intake and exhaust runners (OEM [Kohler] block): $175.00 labor, plus return shipping & handling.
  • Install oversize valves, and port/polish intake and exhaust runners (aftermarket [Kohler] block): $300.00 labor, plus return shipping & handling.
  • Install thin-wall bronze sleeves in worn OEM valve guides in Kohler and other makes of engines. $12.00 each. In most cases, worn valve guides don't necessarily need to be replaced. They can be repaired with a thin-wall bronze liner, like the ones installed in automotive cylinder heads. Also, a bronze liner will last longer than a cast iron guide because bronze retains more oil for better lubrication for the valve stem.
  • Install OEM-type [centered] cast iron valve guide or offset valve guide in OEM Kohler block and ream for clearance of valve stem: $15.00 each labor only, plus return shipping & handling. Price does not include guide.
  • Install bronze offset valve guide in OEM Kohler block and ream for clearance of valve stem: $15.00 each labor only, plus return shipping & handling. Price does not include guide. Oversize valve MUST be used with an offset guide.


Want to use slightly larger valves and run a slightly higher lift cam without installing either? If you do, then read on...

Modifying the Stock Valves and Seats for Improved Performance -

First of all, part of what makes an engine produce power is proper sealing of the valves with the valve seats. They must form a perfect seal so the air/fuel mixture will be trapped within the combustion chamber on the compression stroke. If you're using or if rules require you to use stock valves, more performance can be had by running the valves on the edge of the face. Create a minimum .030" face width for intake and .060" face width for exhaust. Enlarge the seats to match the valves and make them the same width as the valve faces, which is .030" for the intake and .060" for the exhaust. Reworking the valves and seats like this is like having slightly larger valves. And lightening of the valve heads (make them lighter in weight) will provide easier lifting and a faster closing response times, to gain a few more rpm and more power and torque. By grinding away the underneath part of the intake valve head to make it thinner, and regrinding the face at a 30º angle (instead of the factory 45º angle) will gain two things: This will make the valve lighter in weight, and it'll increase the airflow. But leave the exhaust valve face at the factory 45º angle, to prevent it from becoming concaved (collapsed in the center) over time. Grind the underneath of each valve close to the face-to-seat mating area, to improve overall flow at full valve lift.

View showing stock (OEM) valves and reworked valvesTo perform a high-performance valve job, grind a 30º angle on the face of the intake valve and a 31º angle on the seat. Lap the valve(s) in their seats with valve grinding (lapping) compound, clean off the lapping compound, then cut or grind away the metal under the head next to the lapping area and then swirl-polish (smooth the metal) underneath the intake valve head so air/fuel will be undisturbed as it enters the combustion chamber. Because any restriction of the incoming air through the intake opening will not allow an engine to produce more power. The 30º angle plus the undercutting and swirl-polishing will add approximately 15% more airflow at higher rpm, which equals to about 2-3 more horsepower to an engine that originally had a 45º angle on the intake valve and seat. And for the exhaust gases to exit the combustion chamber quickly, grind a 45º/46º angles respectively, and undercut the exhaust valve head. Because any restriction of airflow of the exhaust and intake passageways in and out of the combustion chamber will not allow an engine to rev to its full potential and produce full power and torque at high rpms.

To find the face-to-seat mating area, first grind the seat angles and rework the valves as mentioned above È. Then lap the valves in with valve grinding (lapping) compound, to see where the contact area is. Now remove the metal from the underneath of the head until there is very little metal left next to the contact area. Swirl polishing the underneath of the intake valve head will help, too. This may also need to be done if "shaving" the stock cylinder head. To swirl-polish under a valve head, chuck the valve stem in a drill press, turn it on slow, and then hold a die grinder with a 1" diameter stone (with the die grinder turned on) against the head until it has swirled surface. Then with the valve still in the running drill press, polish the swirled surface with #40 emery cloth by hand until it's somewhat smooth.

There are two ways to remove metal from the underneath of the valve head:


A Stock Cam with Big Valves VS. a Big Cam with Stock Valves?

I think that by using a stock cam with big valves versus a big cam with stock valves wouldn't make that much difference in engine power. Because big valves will allow more airflow in the combustion chamber, plus the cylinder head would need to be machined for the bigger valve for clearance, BUT a stock cam is limited to it's lift and duration. And a big cam would allow the combustion to draw more air, plus the cylinder head would need to be machined for the extra valve lift, BUT the stock valves would limit the amount of airflow. So using one or the other wouldn't work as well as having both of them working together.

With all high-performance cams that have lift of about .400" or more, the lifter bores (part of the engine block) needs to be ground down so the cam lobes can move the lifters up further so they'll clear the block.

Large base lifters are required for cams with a lift above .400". And extreme big tool steel lifters are required for cams with a lift above .572".


Installing Bigger Valves in a Flathead Engine for Improved Performance -

In order for an engine to build up more compression and to gain more power and higher rpms, an engine needs to flow more air (and fuel) in and out of the combustion chamber. Therefore, the valves (and ports) needs to be approximately 22-40% bigger than the originals. For more higher rpms or at wide open throttle, the intake valve needs to be 25-30% bigger than the exhaust valve. In the 10hp and 12hp Kohler engines, the original OEM intake valve can be used in the exhaust hole. If you use your tractor ONLY for competition pulling, an intake valve will hold up just fine in the exhaust hole. Don't worry about it burning. Most pulling tractors don't run long enough to burn valves. (In my personal experience, I've ran an intake valve in my 30ci since 1990 and it has held up just fine.) But if you plan to mow grass and do general yard work too, it'll be best to use a 16hp exhaust valve in the exhaust hole. Most K-series intake valves are made of mild steel, and all Magnum intake (and exhaust) valves are made of extremely hardened steel (Stellite). Exhaust valves are heat treated, to withstand prolong extreme exhaust heat.

On the 16hp engines, a special made or larger automotive valve must be used for both the intake and exhaust, as long as the stem diameter is the same or slightly larger. The valve guide will need to be reamed out to match the larger stem, too. The overall valve length for OEM stock Kohler valves is 4.635". If you have a longer valve that you want to install, the valve stem will need to be shortened and the keeper groove recut in a metal lathe. If using a valve with a larger diameter stem, it's best to narrow the stem diameter in the area that's under the valve head and above the valve guide (port area), which, depending on cam lift and duration, will give about 22% - 40% increase in air flow. Undercutting and swirl polishing underneath the valve heads will increase and smooth the air flow, too. Undercutting also lightens the valves so they'll be less strain on the valvetrain when the cam opens the valves.

On the intake valve side, for every 1/8" increase in diameter, about 1 horsepower is added for a 4,000 rpm limit engine and 2-3hp is added for a non-governed/high-performance wide open throttle engine. Of course, according to the diameter of the intake valve, the exhaust valve will need to be increased by 25%, to quickly rid the combustion chamber of the burnt gases. And the reason the intake valve is bigger than the exhaust is because air (and fuel) enters the combustion chamber under vacuum and exits under pressure. So there is no need to make the exhaust valve the same size as the intake valve.

The approximate oversize valves have been found to work well in the following most popular Kohler engines. These are for engines that run at wide open throttle. Stock engines that run at around 4,000 rpm can use smaller size valves.

The sizes above È flows best according to the cubic inch displacement and when using a 1.200" carburetor venturi. By the way - the 10hp and 12hp intake valve can be used in the exhaust hole, with the seat removed. And remember this when installing larger valves: The larger the valve head diameter (and higher the lift the cam has), the larger the valve cavity (part of combustion chamber) will need to be (for clearance around and above the valve). A larger combustion chamber will have less compression which means less horsepower. But, more power and compression will be regained if the valve job, use of the right cam and proper valve timing are all matched correctly.

And when installing offset valve guides, take into consideration that if the block has valve seat inserts, with the insert(s) removed, if the face of the oversize valve will make contact with the part of the seat that's farthest from the piston.

Remember, when enlarging the ports, especially the intake port, make it the same size as the venturi in the carburetor or an air restriction (bottle neck) will occur, and the engine will not breath sufficiently at higher rpms. The exhaust port needs to be about 22% smaller than the intake port.


Information About Valve Springs - Top of page

The Reason Most Small Engines Use Low-Pressure Valve Springs Opposed to Much Stiffer Automotive Springs -

Most 4-cycle flathead and OHV lawn and garden equipment small engines have a governor that controls and limits the engine's top speed and allows the engine to rev to around 3,200-3,600 rpms. The valve springs don't need to be very stiff at 3,200-3,600 rpms because the engine doesn't rev fast enough for... 1) the valves to float, and 2) the keepers to become dislodged, causing a valve to disconnect from the retainer. In an OHV engine, this is known as "dropping a valve." Which will likely destroy the engine. For most automotive engines on the other hand, they don't use a governor to limit the engine's rpms. Therefore, they require much stiffer valve springs, especially the OHV engines, so the engine will rev up faster, and to lessen the chance of "dropping a valve."

If an engine is going to turn above 4,000 rpm, stiffer valve springs will need to be installed along with heavy-duty retainers. (And definitely make sure the flywheel is precision balanced or better yet, install a steel flywheel... along with a quality connecting rod that has an inserted bearing.) Stiffer valve springs reduce the chance of "valve float," which occurs at high rpm. (Newton's third law of motion.) Valve float allows the engine to momentarily lose compression, cause fuel to spray out the carburetor and the engine will make a "hunt, hunt" sound. As a result, the engine will lose power, and as the weight of the sled is coming up on the tractor, the engine may not be able to recover.

If one is lucky enough to find some, they could use the inner spring of a high-performance automotive valve spring kit in a single cylinder engine. Stock keepers should work fine, too. To reduce the chance of valve float, use dual springs along with stainless steel valves, hardened retainers and keepers when using a steel cam that has a lot of lift (more than .460" of lift). If using ordinary valves with dual springs, the head of the valve(s) (especially the exhaust valve) might become concaved over time because of the extreme pressure. And make sure that "coil bind" doesn't occur (when the spring become totally collapsed and the coils actually touch each other) when the valve is at full lift. Coil bind could break a good cast camshaft or even bend a steel one.


Using a Small Block Chevy Intake Valve in a Kohler Engine -

1.72", 1.94" & 2.02" Small Block Chevy Intake ValvesSmall block Chevrolet V8 and certain Chevy V6 engine stock intake valves will work in a 10-16hp Kohler engine with excellent results, even with offset valve guides. The 1.72", 1.84", 1.92" or 2.02" diameter intake valve can be used for the intake in a 10-16hp [pulling] engines. The 1.94" and 2.02" Chevy valves will work for the intake in a 16hp/50.5 c.i. [pulling] engine.

Stock intake valves works great as an exhaust valve in a pulling engine because the engine doesn't run long enough for the valve to burn or warp.

The valve stem will need to be shortened next to the keeper groove (make the overall length the same as Kohler valves, which is 4.635".), and the oil seal groove becomes the keeper groove. Being the Chevy valve stem is 11/32" in diameter, the valve guide(s) will need to be enlarged with an 11/32" reamer so the valve stems will have proper clearance.

The Chevy valve head will also need to be lightened and the face (and seat) should be ground at a 30º angle for the intake (for maximum air flow), and 45º for the exhaust. And either the Chevy retainers can be used or stock Kohler retainers can be used with the Chevy valve. But the Chevy keepers or locks must be used because of the larger diameter valve stem. The Chevy retainer will need to be turned down in a metal lathe to fit the smaller aftermarket valve springs that's made for Kohler pulling engines. Don't try use Chevy valve springs in a Kohler engine! They're way too stiff and much too difficult to install in a Kohler engine. Actually, they're almost impossible to compress for installation in a Kohler engine.


Remember to do this when installing bigger valves -

Improving Engine Breathing When Using Bigger ValvesWhen installing larger valves, the tapered area on the engine block around each valve must be ground away for full airflow into and out of the combustion chamber. The area just outside of the valve seats next to the piston area (the area where the valves are angled down into the block) needs to be ground away also so the engine can have full air flow in and out of the cylinder. This is very important because if it isn't opened up there, it'll starve the engine for air/fuel. To check this area for adequate clearance, with the head removed, rotate the engine so each valve is fully opened and then insert a wooden dowell or soft aluminum rod (to keep from scratching the valve face and seat) that has the same diameter of the lift of the cam to use as a plug gauge. Grind the tapered area around the valves enough so with the valves installed, you can fit a soft metal (aluminum rod) between the valve face and seat with the valves at full lift. This is how you get full airflow into and out of the combustion chamber. With the metal ground away, the rod should fit snug under the valve head and seat all the way around each valve. If the plug gauge doesn't fit, the metal on the block just outside each valve seat needs to be ground away, especially toward the piston. Be extremely careful not to let the grounding stone touch the finished seats though!

If you're concerned about doing the above È will decrease the compression ratio, well, it will somewhat. But, by doing so, it'll allow the engine to draw in much more air, producing more compression. In return, it'll produce more power and rpm. I know, we've done this many times with excellent results.

And the only way I found to grind this area of the block is to use a die grinder with a 1" diameter rounded end stone. To keep the stone from touching the valve seat, I rest the side of my right hand on the top of the block (I'm right handed) and slowly and very carefully grind away the metal.


Information About Valve Guides - Top of page

There are two ways to measure the amount of wear in valve guides. One way is with a dial indicator. The other way is with an "go/no go gauge" and a micrometer. It's best to have a local machine shop do the measuring because they have the right tools and they're experienced with such things.

How to Remove and Install Pressed-In Cast Iron Valve Guides in a Cast Iron Block Kohler Engine:

  1. Acquire a 1/2" diameter x 5" long grade 8 bolt. Machine the threads down to .300" so it will become a pilot to fit inside the valve guide. This will be the driver tool.
  2. Remove the valves, springs and retainers. Measure old guides to insure if they are worn or within specs.
  3. To remove worn guides:
    • On the K141 (6¼hp), K160 (6.6hp), K161 (7hp) and K181/M8 (8hp) flathead single cylinder and all flathead twin cylinder Kohler engines, if the lifters (and camshaft) are installed, break off half of the guide inside the valve spring compartment with a flat chisel and a medium size hammer, and then use the machined bolt as mentioned above È and a big hammer to drive the remaining guide out and into the valve spring compartment. If the lifters and cam isn't installed, just drive the entire guide out into the valve spring compartment without breaking it off first.
    • On the 10-16hp flathead single cylinder Kohler engines, rather if the lifters (and camshaft) are installed or not, drive the entire guide out into the valve spring compartment with the machined bolt and a big hammer.
  4. Install the new guide with the machined bolt with a flat washer under the pilot so the guide will be flush inside the intake and exhaust pockets.
  5. The new guides may need to be reamed out with a 5/16" reamer so the valve stems will have proper clearance.

FYI - In most cases, worn valve guides don't necessarily need to be replaced. They can be repaired with a thin-wall bronze liner, like the ones installed in automotive cylinder heads. Also, a bronze liner will last longer than a cast iron guide because bronze retains more oil for better lubrication for the valve stem.


Installing Offset Valve Guides -

Straight vs Offset Valve GuidesThe best way to gain more power and torque from any engine is to increase its compression ratio. On a flathead (valves in block) engine, the way to do this is by moving the valves closer to each other and closer to the piston with the use of offset valve guides. As a result, the combustion chamber can be made smaller and the relocated valves will flow better. Machining for oversized valves (minimum 1.550" for the intake and exhaust) must be installed in order to do this. Stock valves cannot be used with offset guides because the offset guides will move a portion of the valve head off the seat. And an minimum oversized valve head diameter of 1.550" must be used with a guide that's offset at .085". (Stock valves = 1.375". Guide moved .170" [.085" x 2]. .170" + 1.375" = 1.545". Use a valve of 1.550" size.)

Installation of new valve guides usually doesn't require new valves. Although the valves will need to be reground so they will seat better. And to remove the guides, first remove the valves. Then use a long 5/16" grade 8 bolt with a nut threaded on it and a heavy hammer to drive the guides out and into the valve spring compartment. Install new guides by driving them in with a hammer until they are flush with the port. The offset guides may need to be enlarged with a 5/16" reamer so the valve stems will have proper clearance. There are 3 ways to install new valve guides:

Bronze is hard material and it retains oil because it's porous. Go here to learn more about bronze valve guides: K-line Interrupted Spiral Guide-Liners. To help the guides and valve stems last longer, drill a small (1/8") hole crossways through the lower part of each guide in the valve spring compartment so the crankcase oil will help keep the valve stems and guide well lubricated and cool. This will reduce stem-to-guide friction (wear) and it'll help promote smooth valve action, which will help increase horsepower slightly and longevity of the guide.

To remove the valve guides from the 10-16hp Kohler engines, drive them out into the valve spring compartment with a 5/16" diameter grade 8 bolt with a nut threaded on the bolt and a big hammer. Also, after many years of use, some guides can be very stubborn to remove, especially the exhaust one. So instead of removing the old guides from an engine with stock valves, have them reamed to accept a thin-wall bronze liner. Besides, all new OEM guides needs to be reamed for the valve stem to fit anyway. So why not have a bronze liner installed instead? Installing CLASSIC Bronze-Liners

When thin-wall bronze valve guide liners are installed, first, the valve guide is reamed the same o.d. as the liner. Then the liner is inserted in the guide, and an air-operated valve guide driver is used to expand the liner in the guide so it'll have the correct clearance for the valve stem.

To bore the offset center hole in a guide, drill the hole in the guide approximately .085" offcenter with the guide firmly clamped in a super spacer (with a self-centering 3-jaw chuck) that's fastened on the table of a vertical milling machine. When drilling bronze, use a non-oily lubricant, such as brake cleaner.

Advertisement:
If you need any of the tools listed below Ê, please contact A-1 Miller's Performance Enterprises | 1501 W. Old Plank Rd. | Columbia, MO 65203-9136 USA | Phone: 1-573-256-0313 (home/shop) | 1-573-881-7229 (cell/text). Please call Monday-Friday (except Holidays), 9am to 5pm, Central time zone. If no answer, please try again later. (When speaking with Brian, please be patient because I stutter.) Fax: 1-573-449-7347. E-mail: pullingtractor@aol.com. Send a message with Yahoo Messenger: | Directions to our shop | Yahoo! Maps, 1501 W. Old Plank Rd., Columbia, MO | 1501 West Old Plank Road, Columbia, MO - Google Maps or Map of 1501 West Old Plank Road, Columbia, MO by MapQuest. Click here for more parts and services. | NOTE: To place an order, please call or send an email with a list and description of the parts or services you need. Because as of right now, we're not set up to accept orders through our web sites online. Due to the rising cost of... everything, prices are subject to change.
Valve Guide Removal and Installation Tool. Use with a big hammer to remove and install valve guides. $10.00 each, plus shipping & handling.
Straight Flute High Speed Steel Precision Chucking Reamers. Perfect size to ream out new valve guides to OEM Kohler specs or installing Chevy valves in Kohler engines. Will not make valves too loose or too tight.
  • 5/16" Reamer. Dimensions: diameter of cutter: .310", flute length: 1-1/2", overall length: 6". $12.00 each, plus shipping & handling.
  • 11/32" Reamer. Dimensions: diameter of cutter: .340", flute length: 1-1/2", overall length: 6". $12.50 each, plus shipping & handling.


How to locate where to machine the cylinder head for the valves...

  1. Strip the engine down to the bare block.
  2. Fasten the billet cylinder head and head gasket on the block with a couple of bolts.
  3. Run a 5/16" diameter steel rod that has a sharp point on one end into each valve guide from inside the block with the pointed end toward the head.
  4. Using a hammer, lightly tap on the end of the rod so a small impression (punch mark) will be created on the head. These punch marks are the locations for the center of the valve heads.
  5. Using a machinists' inside divider caliper, scribe a circle (radius) around each punch mark the same diameter as the valve heads, plus approximately .100" for additional clearance around the valves.
  6. Now the cylinder head can be machined for the valve cavities and combustion chamber.

How to check for proper valve clearance between the valves and cylinder head...

  1. For the 10-16hp engines, set the valves at their respective clearances. (See above È.) Adjustment is made with a flat feeler gauge and with the lifter held in place with a slender 1/2" open-end wrench and turning the adjuster screw in the lifter with a 7/16" open-end wrench. Make sure the lifters are on the base circle of the cam lobes, too.
  2. Place a small amount of modeling clay on each valve head and under the head in each valve cavity. (Place some oil on each valve and valve cavity to keep the clay from sticking to either.)
  3. Place the head and gasket on the engine and tighten down a couple of head bolts.
  4. Rotate the crankshaft slowly by hand 360°. If it stops rotating, do not force it, because damage may occur to the camshaft. Remove the head and see if one of the valves made contact with the head.
  5. If the crankshaft rotates freely after 360°, remove the head and use the depth gauge on a dial or digital caliper to determine the thickness of the clay. The clay should have a minimum thickness of about .070".
  6. Remove metal from inside head (valve cavities) as necessary to gain proper clearance.
  7. Clearance around the valves should be the same as above the valves (valve shrouding).
  8. Repeat steps 2 through 6 to gain proper valve to head clearance.

FYI - One valve I found is an exhaust valve made for a Wisconsin engine. It's a Perfect Circle part #211-1832. It has a 1.590" diameter head and 5/16" diameter stem. Overall length is 4.865". But Kohler valves are 4.635" in overall length. This means the stem will need to be shortened .230" and a new keeper groove will need to be machined. Check at a local auto parts supply store for this valve. They can usually get any size or type of valve you want.

If one is extremely careful, bigger valves can be installed using a pneumatic (air-operated) die grinder with an ordinary grinding stone and an electric valve seat grinder. There's no need to install valve seat inserts either. Just cut or grind the new seats directly into the cast iron block. For best flow and compression, the high point of the seat needs to be even with the deck of the block. If the seat is made too deep, valuable flow and compression will be lost! Most blocks can be decked to regain the compression, though. (If rules allow it.)

For best valve flow, cut or grind the intake valve face and seat at a 30° angle, and the exhaust valve face and seat at a 45° angle. Give the intake seat about a .030" width, and the exhaust seat about a .060" width. Make the valve face mating surface near the edge of the valve, too.


What is Port and Polish (or Porting and Polishing)? - Top of page

"Porting" is when the intake and exhaust ports (runners) in a flathead engine block or OHV cylinder head are made larger in volume so more air/fuel can enter the combustion chamber and the exhaust gases can exit quicker so the engine will produce higher compression pressures which results in more power and torque at higher rpm.

"Polishing" is when the ports are made smooth. Many years ago, most high-performance engine builders thought that by making the intake port and intake manifold (or carburetor extension, spacer, intake tube, stand-off, or whatever they may be called by garden tractor pullers), smooth and polished, this would help the engine to produce more power and torque. Which in theory makes sense. But in reality and in recent dyno tests, the intake passageway shouldn't be smooth or polished. If enlarged (for more airflow), but made with a rough surface, this will create turbulence in the port. The turbulence will cause the incoming air to atomize with the fuel vapors more thoroughly, which will help the engine produce much more horsepower and torque at high rpms or at wide open throttle. The exhaust port and header pipe on the other hand, should be smooth and polished, so the spent exhaust gases can exit the combustion chamber quickly and smoothly.


An Easy and Sure Way to Determine the Port Size and Flowing the Ports -

When enlarging the ports and to determine the correct size of each port, make a couple of "plug gauges" from a 1.200" diameter fender washer for the intake port (to match a 1.200" carburetor) and a 1.000" washer for the exhaust port, which can be mounted on a long bolt. Click HERE for a better understanding about the shape of the intake runner port. When grinding the ports, feel each port for smoothness. Give the intake runner a fine hone finish. This will help to atomize the fuel with the air. Do the same with the exhaust runner. Because any roughness will disrupt the atomization of the fuel with the air, causing loss of power.

For best engine performance, the port runners should be enlarged to match the diameter of the carburetor's bore. To port out an engine block, a pneumatic die grinder with a large, long pointed stone could be used, but this method is VERY time consuming and tiresome. It takes about 5-6 hours of labor with a die grinder... and a good air compressor. For much faster and accurate results, a 1/2" pneumatic [air operated] drill with a large quality [high speed steel] drill bit can be used. This is how I enlarge the ports on an engine. After I "drill them out," I then use a pneumatic die grinder with a 1" diameter pointed stone for a smooth finish. It takes only about 10 minutes to enlarge the ports in an engine with a large drill bit and a pneumatic drill. Use a large diameter drill bit (either 1.07" or 1.2") to match the diameter of the carburetor's throttle bore. The intake port doesn't have to be no bigger than the carburetor's throttle bore that's going to be used on the engine. When facing the intake port, hold the drill bit so it's positioned slightly downward and angled slightly to the right for best air flow through the port and into the combustion chamber. The drilling process should leave the port pretty smooth and straight. But if there are a few rough spots, they can be smoothed with a die grinder/stone. Don't use an electric drill, even a heavy duty one, to port out an engine! A very large drill bit will likely to "catch" or get "hung up" in the cast iron port during the drilling process and this will cause the reduction gears in the drill to strip out.

Degree of the Intake Center Line -

The intake centerline angles that I use when I port a 10-16hp Kohler engine are 4° down and 4° to the right when standing to the side of the block.

If an engine has hardened exhaust valve seat(s), unleaded gasoline has no effect on the wear of the seat(s). In fact, all engines built nowadays or since unleaded gas was first introduced have hardened exhaust valve seats. Valves are unaffected by unleaded gas. Also, unleaded gas helps to keep the combustion chamber free of carbon deposit buildup.


Information about Valve Lifters (Tappets) - Top of page

About a Worn Lifter Adjuster Head and Face -

When adjustable Kohler lifters wear, sometimes the center of the adjuster head will wear or become concaved, which will affect valve adjustment if not made perfectly flat again. The head will need to reground on a valve grinding machine until it's perfectly flat again.

When flat tappets or lifters are manufactured, the center of the lifter face (the part that makes contact with the lobe on the cam) is slightly raised (approximately .001"). The lifter sits slightly off-center of the cam lobe so when the valve opens, the lobe rotates the lifter slightly to prevent wear to either part. Otherwise, if the lobe is centered with the lifter, the lobe will scrape the lifter when the valve opens, causing excessive wear to both the lifter and lobe in a short time. If you need to replace a worn lifter (and undoubtedly the camshaft, too), the best thing to do is acquire a good used lifter (I have a bunch of good used OEM Kohler lifters in stock) or purchase a new one. It is almost impossible to "reface" a lifter because they're made of extremely hardened steel. A good used lifter can be successfully reused with a new or used camshaft without wearing the cam lobe. What needs to be done to prevent wear to the lobe is roughen the face of the lifter with 600 grit sandpaper until all the shiny surface is gone. This will provide a new wear pattern for the lifter and lobe. For break-in of the lifter and lobe, use SAE 30 weight conventional (petroleum-based) motor oil with high zinc content to provide a protective film as the parts wear into each other, producing a hardened surface wear pattern. If a lifter face is pitted with rust, it will need to be replaced with either a good used lifter or a new one. And if the cam lobe(s) are worn, then either replace it with another good used camshaft, or for a 10-16hp Kohler camshaft, the lobes can be welded up and professionally reground to turn it into a performance camshaft.

Wide Base Lifters -

If you want to get a lot of power from your engine, and all you want to do is install a big cam with a lot of lift and duration, well, installing a big cam alone in an engine won't help it to produce a lot of power. The reason is because engines are basically an air pump. Big cams moves A LOT of air in and out of an engine. They also perform best at very high rpm. Here's some things an engine will also need with a big cam:

By the way - the adjustable, 1.28" diameter wide base lifters (tappets) that's used in the 10-16hp flathead Kohler engines with a high-performance cam originally come in the following early model Chrysler product vehicles. (They are definitely NOT Jeep lifters!)

Using Hydraulic Lifters in a High-Performance Engine -

When pulling (or racing) virtually any engine that have hydraulic flat bottom or roller valve lifters (such as Kohler Command), to prevent the lifters from "pumping up" with oil at high rpms or at wide open throttle which may cause the valves not to fully close, simply set the valve clearances at zero lash with no preload. By doing this, the lifters will always be pumped up, allowing the valves to fully close at any rpm and allowing the engine to produce full power.


Information about the Camshaft and How to Degree in a Steel Cam - Top of page

The most important part of any high-performance engine is the camshaft. It's the heart of the engine. To be truly competitive on the track, a high-performance engine really needs the latest and updated cam that's available. Installation of a special camshaft is important if increased performance is to be obtained. Simply put, the cam tells the valves what to do, when to do it and for how long. Performance camshafts lift the valves higher and hold them open longer in relation to piston travel than stock cams. The increased lift is known as "valve lift" and when the valves stay open longer, this is known as "duration." Cams with much more lift and duration than a stock or a reground low rpm torque cam is considered a "performance cam."

How a high-performance cam with more lift and a lot of duration works -

Air is very flexible. It can be compressed as well as it can be expanded. When an engine has a long duration cam, with the cylinder head off, as the crankshaft is slowly rotated by hand, you may notice that before the piston reaches TDC (Top Dead Center) or BDC (Bottom Dead Center), the valves stay open longer and doesn't fully close until the piston is a good ways up or down in the cylinder. This is called "duration." With an OEM stock cam or short duration cam, the valves will become fully closed when the piston is at or close to TDC or BDC. Anyway, with a long duration cam, when an engine revs at high rpms or at wide open throttle, air doesn't have time to exit out through the valves, so it "compresses" and becomes trapped within the combustion chamber. In this way, the piston can draw more air (and fuel mixture) into the combustion chamber through the intake valve. The engine is able to build up more compression at higher rpms with a long duration cam so it will produce more power. In addition, a larger portion of the burned gases will be expelled from the combustion chamber through the exhaust valve. This is why most high-performance automotive engines with a long duration cam idle "radically" or with a low tone, loping sound, and single cylinder pulling engines have a bellowing "BOOM, BOOM" sound out the exhaust with an open header pipe. That's air the piston is pushing out past the exhaust valve before the valve can fully close at a high rate of speed, creating a small sonic boom. The reason it makes a loud sound is because the air is moving faster than the speed of sound, which breaks the sound barrier.

Also, cylinder head clearance, improved carburetion, larger valves and stiffer valve springs are a must in order to take full advantage of a bigger cam. And always use the 1.280" diameter wide base lifters with a cam that has at least .400" of lift despite the duration. Use of the right cam and proper valve timing can help an engine come to life and scream down the track!

When using a billet steel camshaft with minimum .575" of lift and dual valve springs, it's best to use a billet steel cam gear also. Because if a cast iron gear is used, the gear teeth could break when the cam comes around right when lift occurs, which will likely break the gear teeth on the crankshaft, too. Also, the "shrapnel" of loose broken gear teeth flying around in the crankcase could become lodged between other moving parts, destroying them as well.

The proper installation of the camshaft is very important for full power and torque. The camshaft is the heart of your engine and if it isnít installed properly, the whole engine will run sluggish. Camshaft degreeing is the one most important thing that can be done to an engine. If the camshaft isn't degreed in, odds are it will usually be too far advanced or retarded. I highly recommend that you properly degree your camshaft. Step-by-step method of how to degree your camshaft is listed below Ê. If your camshaft can move back and forth in your engine, you are losing power. When your camshaft moves forward, your ignition timing becomes retarded, which makes your engine run sluggish.

BE AWARE! Lifts up to .432" can safely be put on the Kohler cast cam. A Kohler cast iron camshaft with more lift than .432" lift that has both lobes welded-up and reground for more lift and duration is not expected to live long with stiffer-than-stock valve springs. The more lift a cast cam has, the more likely it is to break. It's only a matter of time. They break next to the gear. The reason they break is because the support pin flexes under load (valve lift), and cast iron doesn't. That's why if a cast cam is used, it's best to use a support pin made of hardened steel.

When rebuilding a Kohler engine or installing another [cast] camshaft, check the cam pin for wear. If it's worn, this will allow the cam to "wobble around" at high engine rpm resulting in erratic valve action, and it'll cause the ignition timing to be very erratic, which will cause the engine to run erratic and lose power. A cam running on a worn pin will even make the engine "pop" and backfire out the exhaust at high rpm.

The OEM cast iron camshaft in the 4-16hp Kohler engines is held in place by a single long pin that goes in from the flywheel end of the block, through the cam and is wedged in the PTO side of the block. To remove it, use a long, hardened 3/8" diameter (for the 7hp & 8hp engines), 7/16" diameter (for the 10-16hp engines) bolt or steel rod and a medium size hammer, and drive it out from the PTO side of the block. It comes out on the flywheel side. Replacement is in the reverse order of removal. Be sure to reset the valve clearances after the new pin is installed. As the cam pin is driven out, be sure that the shim(s) (very flat washers) that's on the end of the cam towards the flywheel end don't fall out of place.

When using a cast cam in an engine that runs at wide open throttle, be sure to install heavier-than-stock valve springs to prevent valve float at high rpm. And make sure to use high zinc oil, not a multi-weight for newer engines. Without the zinc, it will wear the lobes. High zinc examples are: Delvac, Cen-Pe-Co, Amsoil Dominator, Red Line, Brad Penn, Rotella, Joe Gibbs, and others. Just check it out before you buy.


How a Long Duration Camshaft Works -

An engine that has a stock camshaft and when it is at an idle speed, about 95% of the air that enters the engine becomes trapped within the combustion chamber. This does not change as engine speed increases. But with a long duration cam that has "humped-up" lobes, at idle speed, some of the air that enters the combustion chamber, and being the valves stay open longer, exits through the intake and exhaust valves. (This is why engines with a high-performance camshaft idles rough. The more duration a cam has, the rougher the engine will idle.) Anyway, as engine speed increases, and being air can be compressed as well as it can be expanded, the air will eventually become trapped within the combustion chamber. This "trapping of the air" builds up the pressure within the combustion chamber. Thus, allowing the engine to produce more power at higher rpm. The faster an engine revs up, the more air will become trapped in the combustion chamber. (This is also why engines with a high-performance camshaft runs smooth as engine speed increases.)

Have you ever noticed that when the piston is on the exhaust stroke, how each valve is slightly open? Well, that's called valve overlap. It's normal on all camshafts. It scavenges the exhaust gases from the combustion chamber and creates more vacuum for the incoming air/fuel. It happens only when the piston is on the exhaust stroke. And both valves are fully closed on the compression stroke.

The Cause of Carburetor Flooding at Slow Idle with a Long Duration/high-performance Camshaft - Top of page

Sometimes when using a long duration/high-performance camshaft, despite if the engine has a modified or stock carburetor, if the engine idles for a long period of time, it may run rich on fuel at slow idle speeds. What happens is with a long duration cam, intake vacuum is low and with a single cylinder engine, excess fuel builds up in the intake extension/port. Any engine that has a long duration camshaft have low vacuum at slow idle speeds. The longer the duration, the lower the vacuum. What causes excess fuel to build up in the intake is the long duration of the cam lobes holds the [intake] valve open longer, and at slow idle, the pressure of the piston blows some of the air/fuel back into the intake tube. The more duration a cam has, the worse this will be. As the engine is accelerated, black smoke or raw unburned fuel will blow out the exhaust until the fuel is cleared out of the intake tube. With the engine running well above idle, air becomes trapped within the combustion chamber and the piston don't have time to blow any air/fuel back into the intake. This happens with gas, E-85 or 100% methanol fuels, and there's nothing that can be done about it. There's probably nothing wrong with the carburetor, and nothing can be done to the idle circuit to prevent this. Just make a simple adjustment with the idle air/fuel mixture screw so the engine idles smoothly, and don't allow the engine to idle for a long period of time.


Kohler's Old Style Two-Piece Camshaft -

If you've ever seen a Kohler camshaft that's made in two pieces (not broken in two), these were original equipment from the factory and came in all K141 6¼hp engines and the very early K241 10hp engines up till 1964. These cams were made before the automatic compression release mechanism came into existence. Instead, theses cams have an ignition timing retard mechanism. With this type of cam, the engine would start under full compression, making it hard on the starter/generator (if it wouldn't start right away, the battery would eventually drain). At cranking speed, the ignition timing is positioned at 0° TDC so the engine wouldn't "kick back" under full compression. when attempting to start it. "Kick back" occurs when the flywheel/crankshaft suddenly and violently rebounds or momentarily rotates in the opposite direction, which is could bend or break the starter armature shaft or the aluminum starter housing. After the engine starts, spring-loaded flyweights on the cam gear automatically rotates the point lobe slightly, advancing the timing to 20° BTDC so the engine can produce full power. These cams have the same lift and duration as the newer, one-piece camshaft with the automatic compression release mechanism.

These cams have the same lift and duration as the newer ones with the compression release, and the other difference are as follows:

If you choose to reuse this camshaft to keep the engine "all original," when reinstalling the cam in the engine block, make sure the timing marks on both the cam gear and ignition cam (points lobe) are aligned, or the ignition timing will be 180° off and the engine will not start! Also, make sure the springs that's on the flyweights are properly positioned on the points lobe so there's pressure on each spring and so the timing advance flyweights can move inward and outward when the engine is shut down, and started up.

NEVER INSTALL A CAMSHAFT DRY! Always lubricate the pin and inside the camshaft with plenty of motor oil or grease before reinstalling the cam in the block! Failure to do so, just after starting the engine, friction from dry running will cause the cam to seize on the pin. Severe damage to the pin, cam and engine block will result!

When setting the ignition timing on the engine with this type of cam, set the points so they just begin to open with the piston positioned on the compression stroke at 0° TDC (T mark on the flywheel). When the engine starts, the points lobe automatically rotates slightly, advancing the timing to 20° BTDC. Don't set the timing at 20° BTDC (S mark on the flywheel) with this type of cam! Because setting it at 20° BTDC will cause the engine to "kick back" when attempting to start it. "Kick back" occurs when the flywheel/crankshaft suddenly and violently rebounds or momentarily rotates in the opposite direction, which is could bend or break the starter armature shaft or the aluminum starter housing. And if it does start, the timing will automatically be advanced to 40° BTDC, which will cause the engine to run too hot and prematurely wear out. Return To Previous Web Page.


Removing the Camshaft -

Kohler's cast iron camshaft is held in place by a 1/2" diameter steel pin that goes all the way through the cam and engine block. The camshaft is removed by first removing the flywheel, aluminum bearing plate, piston/rod assembly and crankshaft. Then use a long steel rod that's slightly smaller than 1/2" in diameter and a medium size hammer to drive out the pin from the PTO end of the block. (See the picture to the right.) And when reinstalling the pin, drive it in from the flywheel side until it's flush with the block. The hole in the PTO end of the block is tapered to secure the pin in place.

NEVER INSTALL A CAMSHAFT DRY! Always lubricate the pin and inside the camshaft with plenty of motor oil or grease before reinstalling the cam in the block! Failure to do so, just after starting the engine, friction from dry running will cause the cam to seize on the pin. Severe damage to the pin, cam and engine block will result!

To prevent damaging or cracking the engine block, drive out the camshaft pin from the PTO end towards the flywheel end. Do not drive out the pin from the flywheel end! Doing this could also crack or break the camshaft! The hole on the PTO end of the block for the cam pin is tapered. This is what secures the pin in place.

When reinstalling the cam pin in the block, drive the pin in until it's flush with the FLYWHEEL end of the block. The hole for the pin in the PTO end of the block is tapered, so the pin should have a snug, press-fit. And Kohler didn't originally apply sealant in this hole for some reason. So to prevent an oil leak, clean the oil from inside the hole with cleaning solvent (paint thinner), allow to thoroughly dry, and then fill the hole with Clear RTV Silicone Adhesive Sealant. By the way - I've always preferred to use Clear RTV Silicone Adhesive Sealant for two reasons: being it's an adhesive, it bonds parts together, forming a leak-proof seal; and being it's clear, it makes for a clean and professional-looking repair job. It can't be seen between the parts.


The camshaft, lifters and cam pin in the 10hp, 12hp, 14hp, 16hp engines will all interchange. Their camshafts all have the same lift, too. The only exception is the cam that's designed for the 18hp OHV single cylinder cast iron block Kohler engine. It has the same lift as the flathead engine cams (.324"), but increased duration from 223º (flathead cam) to 256º (18hp cam). The 18hp cam will help the 10-16hp K-series and Magnum flathead engines produce more power and torque up to approximately 4,000 rpm. Because of it's limited duration, it won't help to increase the compression much above 4,000 rpm, which makes it ideal for use in a stock governed engine. By the way - the 18hp cam doesn't have enough duration to make the engine have a "loping" sound at idle. It makes the engine sound like a stock short-duration cam.

Advertisement:
If you need any of the items listed below Ê, please contact A-1 Miller's Performance Enterprises | 1501 W. Old Plank Rd. | Columbia, MO 65203-9136 USA | Phone: 1-573-256-0313 (home/shop) | 1-573-881-7229 (cell/text). Please call Monday-Friday (except Holidays), 9am to 5pm, Central time zone. If no answer, please try again later. (When speaking with Brian, please be patient because I stutter.) Fax: 1-573-449-7347. E-mail: pullingtractor@aol.com. Send a message with Yahoo Messenger: | Directions to our shop | Yahoo! Maps, 1501 W. Old Plank Rd., Columbia, MO | 1501 West Old Plank Road, Columbia, MO - Google Maps or Map of 1501 West Old Plank Road, Columbia, MO by MapQuest. Click here for more parts and services. | NOTE: To place an order, please call or send an email with a list and description of the parts or services you need. Because as of right now, we're not set up to accept orders through our web sites online. Due to the rising cost of... everything, prices are subject to change.
Nylon Governor Gears. Good for up to 4,000 rpm. OEM Kohler part # A-235743-S.
  • Used and in excellent condition: $20.00 each, plus shipping & handling. [When available.]
  • New: $39.50 each, plus shipping & handling.
Cast Iron Governor Gear. Good for above 4,000 rpm up to wide open throttle. Will not explode or flex at high rpms like the nylon governor gears sometimes do. OEM Kohler part # A-237031. (Discontinued from Kohler.)
  • Used and in excellent condition. $60.00 each, plus shipping & handling. [When available.]
New hardened steel thrust washer for nylon or cast iron governor gear. Kohler # 237022-S.
  • Aftermarket. $2.00 each, plus shipping & handling.
  • OEM Kohler part. $3.70 each, plus shipping & handling.
3/8" diameter stub shaft for governor gear in 6¼hp-16hp Kohler single & twin cylinder flathead engines. Kohler part # 235125-S.
  • Aftermarket. Precision ground, heat-treated alloy steel. $15.00 each, plus shipping & handling.
  • OEM Kohler part. $43.45 each, plus shipping & handling.
New Style One-Piece Camshaft for Kohler K-series or Magnum engine models K141 (6¼hp), K160 (6.6hp) and K161 (7hp). Not for K181. With ACR. Points lobe, lifter lobes, gear teeth and compression release mechanism are all in good condition. For upgrade from the older two-piece cam or OEM replacement. No longer available from Kohler. IMPORTANT: To prevent seizing of camshaft on pin when engine is ran for the first time, apply plenty of motor oil on cam pin and inside cam before installing cam in engine. This will better protect the parts until crankcase oil reaches them. OEM Kohler part # A-231511-S (nylon gear).
  • Used. $75.00 each, plus shipping & handling. [When available.]

New Style One-Piece Camshafts for Kohler K-series or Magnum engine models K141 (6¼hp), K160 (6.6hp) and K161 (7hp), K181/M8 (8hp). With points lobe and ACR. OEM Kohler part #'s 41 010 05-S.

  • Used. Points lobe, lifter lobes, gear teeth and ACR are all in good condition. $90.00 each, plus shipping & handling. [When available.]
  • New. $181.20 each, plus shipping & handling.

Camshafts for Kohler Magnum engine model M8 (8hp), but can be used in the K-series K141 (6¼hp), K160 (6.6hp) and K161 (7hp), K181 (8hp) engines with the NOVA 2 or Mega-Fire solid state modules. No points lobe. With ACR. IMPORTANT: To prevent seizing of camshaft on pin when engine is ran for the first time, apply plenty of motor oil on cam pin and inside cam before installing cam in engine. This will better protect the parts until crankcase oil reaches them. OEM Kohler part # 41 010 07-S.

  • Used. Lifter lobes, gear teeth and ACR are all in good condition. $50.00 each, plus shipping & handling. [When available.]
  • New. $104.45 each, plus shipping & handling.

If you need a high-performance camshaft for a Kohler K181 or M8 engine, contact Vogel Manufacturing Co. at: http://www.vogelmanufacturing.com.

NOTE: When reusing lifters, roughen lifter faces with 600 grit sandpaper to produce a new wear pattern and so the lifters will rotate slightly with every lift to prevent wear to the cam lobes. And the K141 (6¼hp), K160 (6.6hp) and K161 (7hp) cams can't be used in the K181 (8hp) engine due to its longer stroke. ACR = automatic compression release.

New Style One-Piece Camshafts for Kohler K-series or Magnum engine models K241/M10 (10hp), K301/M12 (12hp), K321/M14 (14hp) or K341/M16 (16hp). For upgrade from the older two-piece cam or OEM replacement. IMPORTANT: To prevent seizing of camshaft on pin when engine is ran for the first time, apply plenty of motor oil on cam pin and inside cam before installing cam in engine. This will better protect the parts until crankcase oil reaches them. OEM Kohler part #'s 45 010 06-S (Various K341's or M16's; $173.62), 47 010 06-S (All K241's, and various K301's, K321's or K341's engines; $198.29) or 47 010 09-S (Various K301's, K321's or K341's engines; $154.30). (They're all basically the same.)
  • Used. Points lobe, lifter lobes, gear teeth and ACR are all in good condition. $75.00 each, plus shipping & handling. [When available.]
  • New. $154.30 each, plus shipping & handling.

Magnum Camshafts for Kohler engine models M10 (19hp), M12 (12hp), M14 (14hp) and M16 (16hp). (No points lobe.) IMPORTANT: To prevent seizing of camshaft on pin when engine is ran for the first time, apply plenty of motor oil on cam pin and inside cam before installing cam in engine. This will better protect the parts until crankcase oil reaches them. OEM Kohler part # 47 010 11-S.

  • Used. Lifter lobes, gear teeth and ACR are all in good condition. $60.00 each, plus shipping & handling. [When available.]
  • New. $122.00 each, plus shipping & handling.

NOTE: When reusing lifters, roughen lifter faces with 600 grit sandpaper to produce a new wear pattern and so the lifters will rotate slightly with every lift to prevent wear to the cam lobes. And the lobes on the used cams have not been reground for performance, and we have no 18hp cams available.

Professionally Reground 4,000± RPM Performance Torque Cam for Kohler K-series and Magnum engine models K241/M10 (10hp), K301/M12 (12hp), K321/M14 (14hp), K341/M16 (16hp) and K361 (18hp OHV). This cam profile has stock lift with increased duration and will pass tech for a stock cam. It will add about 3 more horsepower and 2 ft. lbs. of torque to an average stock engine with more lugging power than the OEM Kohler K361 (18hp OHV) cam. When pulling, this cast cam performs best with medium-performance valve springs (below Ê), reworked and undercut stock size valves for more airflow, ports made larger and the venturi in the carburetor bored out. If there's any restriction in and out of the combustion chamber, the cam will not be able to perform at 100% efficiency, and the engine will not be able to produce as much power. This cam profile helps the engine produce the most power and torque between 3,600-4,500 rpms. At higher rpms, no substantial increase in power will result. Tested and proven design over the competitor's. If engine is built to the max, tractor is geared correctly and traction is adequate, engine shouldn't bog down much with this cam. It'll keep pumping out the ponies right out the gate. This cam sounds just like an OEM stock cam. You can't hear the difference out the exhaust. It's perfect for a competing stock pulling tractor or for heavy yard work. Use with OEM Kohler 1" base lifters. When reusing lifters, roughen lifter faces with 600 grit sandpaper to produce a new wear pattern and so the lifters will rotate slightly with every lift to prevent wear to the cam lobes. This cam installs just like the OEM cam. Just thoroughly lubricate the inside with motor oil, align the timing marks on the gear teeth, set the end-play and valve clearances to OEM specs, and it should be good to go!

FYI: When the cam lobes are reground, metal is removed from the base circle which reduce the diameter of the base circle in order retain maximum lift at the point on the lobe. The ramps on the lobes are also "rounded" to give the cam more duration. The cam grinding machine's grinding stones are about 1" wide, and after the cam grinding process, I have to manually grind metal away from the sides of the base circles so the edge of the lifters won't "ride up" on the unground areas and hold the valves slightly open when they're supposed to be fully closed. I have to do this to every reground cam I have in stock. (Some cam grinders apply a protective coating (paint) to the entire camshaft to cover the grinding marks on either side of the base circles of the lobes. But if you look closely, you can still see the grinding marks.) Otherwise, if everything else is set up correctly with your engine, this cam should work fine. There's no need to be concerned when you receive the cam and see the metal ground away. Also, some of the cams I have, the points lobe is slightly worn. (It's hard to find a good used, 100% unworn cam nowadays.) I include a stainless steel points pushrod with a flared end to make contact with the unworn areas of the lobe. The pushrod will need to be installed from inside the block before the cam is installed.

  • Outright: $150.00 each, plus shipping & handling.
  • With core trade-in: $125.00 each, plus shipping & handling. Only the one-piece cam (originally with the automatic compression release) will be accepted as a core. Core must be in good condition, no cracks, never reground or welded on before with gear teeth in good condition, minimal wear on points lobe and preferably the compression release tang intact. When sending a core to me, please include a note with your name, mailing address, phone number and that you want to trade the cam in as a core for the Reground Torque cam. I will then deduct $25.00 from the price of the cam. Please send your core to: A-1 Miller's Performance Enterprises, 1501 W. Old Plank Rd., Columbia, MO 65203-9136 USA.
  • IMPORTANT: To prevent seizing of camshaft on pin when engine is ran for the first time, apply plenty of motor oil on cam pin and inside cam before installing cam in engine. This will better protect the parts until crankcase oil reaches them.
Hot-Stock and Stock-Altered high-performance Camshaft for Kohler K-series and Magnum engine models K241/M10 (10hp), K301/M12 (12hp), K321/M14 (14hp), K341/M16 (16hp) and K361 (18hp OHV) Pulling Engines. This is a much more aggressive camshaft than above. Lobes are hard surface welded on an OEM cast cam, then professionally precision ground to give it a stock lift (.325"-.330"), but much more duration (290°). This cast cam performs best with high-performance valve springs (below Ê), reworked and undercut stock size or oversize valves for more airflow, ports made larger and the venturi in the carburetor bored out. If there's any restriction in and out of the combustion chamber, the cam will not be able to perform at 100% efficiency. Due to the increased duration, with an open header pipe, there is a bellowing "BOOM, BOOM" exhaust sound upon deceleration and at idling speed with this cam. This cam profile helps the engine produce the most power and torque at wide open throttle operation. If used in a 4,000± rpm engine, no substantial increase in power will result. Can be used with OEM Kohler 1" base lifters. When reusing lifters, roughen lifter faces with 600 grit sandpaper to produce a new wear pattern and so the lifters will rotate slightly with every lift to prevent wear to the cam lobes. This cam installs just like the OEM cam. Just thoroughly lubricate the inside with motor oil, align the timing marks on the gear teeth, set the end-play and valve clearances to OEM specs, and it should be good to go! If methanol fuel is going to be burned in the engine and the ignition timing advanced more than 25° BTDC (with points), the automatic compression release mechanism on this cam will need to be removed and a high torque starter motor will need to be used. Otherwise, this cam with the automatic compression release mechanism should work fine with gas with the timing set no more than 22° BTDC.
  • Outright: $180.00 each, plus shipping & handling.
  • With core trade-in: $155.00 each, plus shipping & handling. NOTE: Only the one-piece cam (originally with automatic compression release) will be accepted as a core. Older, out-dated steel cams for Kohler flatheads will be accepted, too. Core must be in good condition, no cracks, never reground or welded on before with gear teeth in good condition, minimal wear on points lobe and preferably the compression release tang intact. If core has a worn lobe, but the rest of the cam is in good condition, that would be fine because it will need to be welded up (and then reground) anyway. When sending a core to me, please include a note with your name, mailing address, phone number and that you want to trade the cam in as a core for the Reground Torque cam. I will then deduct $25.00 from the price of the cam. Please send your core to: A-1 Miller's Performance Enterprises, 1501 W. Old Plank Rd., Columbia, MO 65203-9136 USA.
  • IMPORTANT: To prevent seizing of camshaft on pin when engine is ran for the first time, apply plenty of motor oil on cam pin and inside cam before installing cam in engine. This will better protect the parts until crankcase oil reaches them.
OEM Stock Valve Springs for Kohler K-series and Magnum engine models K241/M10 (10hp), K301/M12 (12hp), K321/M14 (14hp), K341/M16 (16hp), K361 (18hp OHV), K482, K532 and K582. Recommended for general yard use. Good for up to 4,000 rpm with cam having stock lift. NOTE: Used OEM valve springs rarely lose their pressure. They can be reused as long as they're not pitted with rust, which makes a weak spot and could cause them to break over time.
  • Short Valve Spring. Approximately 1-9/16" uncompressed height; for use with rotator retainer. OEM Kohler part # 235168-S.
    • Used and in excellent condition. $4.00 each, plus shipping & handling. (When available.)
    • New. $9.00 each, plus shipping & handling.
  • Long Valve Spring. Approximately 1-3/4" uncompressed height; for use with stamped steel/non-rotator retainer. OEM Kohler part # 235010-S.
    • Used and in excellent condition. $4.00 each, plus shipping & handling. (When available.)
    • New. $9.00 each, plus shipping & handling.

OEM Stock Valve Springs for Kohler KT-series and Magnum flathead twin cylinder engine models MV16, KT17, KT17II, KT19, KT19II, M18, MV18, M20 and MV20. OEM Kohler part # 25 089 01-S.

  • New. $3.60 each, plus shipping & handling.

Medium-Performance Single Valve Springs for Kohler K-series and Magnum engine models K241/M10 (10hp), K301/M12 (12hp), K321/M14 (14hp), K341/M16 (16hp) and K361 (18hp OHV). These are more aggressive than OEM stock springs. For competition pulling only; not recommended for general yard or garden use. Designed for the OEM stock cam or our reground 4,000± rpm torque cam with stock lift in pulling engines running up to 5,000 rpms for quicker valve closing to prevent valve float. (Newton's third law of motion.) Valve float allows the engine to momentarily lose compression, cause fuel to spray out the carburetor and the engine will make a "hunt, hunt" sound. As a result, the engine will lose power, and as the weight of the sled is coming up on the tractor, the engine may not be able to recover. These springs can be used with stock size valves, OEM stamped steel/non-rotator retainers and keepers/locks. OEM rotators are thicker, which may cause coil bind, resulting in possible cam breakage. Can be easily compressed with a standard small engine valve spring compressor. Dimensions: .953" i.d.; .697" o.d.; 2" uncompressed height. Specifications: Seat load: 27 lbs. @ 1.650"; Open load: 70 lbs. @ 1.200"; Coil bind: .920"; Spring rate (lbs/inch): 96. Made by Comp Cams.

  • New. $10.00 per set of two, plus shipping & handling.

High-Performance Single Valve Springs for Kohler K-series and Magnum engine models K241/M10 (10hp), K301/M12 (12hp), K321/M14 (14hp), K341/M16 (16hp) and K361 (18hp OHV). Designed for cams with up to .400" lift in Hot-Stock or Stock-Altered competition pulling engines that run at wide open throttle for quicker valve closing to prevent valve float. (Newton's third law of motion.) Valve float allows the engine to momentarily lose compression, cause fuel to spray out the carburetor and the engine will make a "hunt, hunt" sound. As a result, the engine will lose power, and as the weight of the sled is coming up on the tractor, the engine may not be able to recover. These springs can be used with stock size or oversize valves, OEM stamped steel/non-rotator retainers and keepers/locks. OEM rotators are thicker, which may cause coil bind, resulting in possible cam breakage. Can be easily compressed with a standard small engine valve spring compressor. Dimensions: .953" i.d.; .697" o.d.; 2" uncompressed height. Specifications: Seat load: 55 @ 1.500"; Open load: 127 @ 1.000"; Coil bind: .950"; Spring rate (lbs/inch): 144. Made by Comp Cams.

  • New. $12.00 per set of two, plus shipping & handling.
OEM Kohler Valve Spring Retainers and Rotators. Fits 5/16" diameter valve stems. Fits Kohler K-series and Magnum K141, K160/K161, K181/M8, K241/M10 (10hp), K301/M12 (12hp), K321/M14 (14hp), K341/M16 (16hp), K361 (18hp OHV), KT17, KT17II, KT19, KT19II, KT21, MV16, M18, MV18, M20, MV20, K482, K532, K582 and KT series and Magnum flathead twin cylinder engines.
  • Retainer for Intake Valve Spring. Accepts 7° keepers above È. To be used with 1-3/4" uncompressed length OEM Kohler valve spring, but can also be used with the medium or high-performance valve springs below Ê. May cause valve float at higher rpms if used with 1-9/16" OEM Kohler spring. Heat-treated, hardened stamped steel. Weighs half of billet steel retainer, but just as strong. OEM Kohler part # 230011-S.
    • Used. $2.00 each, plus shipping & handling. (When available.)
    • New. $4.65 each, plus shipping & handling.
  • Rotator for Exhaust Valve Spring. Accepts 7° keepers above È. Scrapes carbon deposits from valve face and seat as valve opens to prevent burning of valve. This particular rotator compresses spring .030" tighter for better valve action. To be used with 1-9/16" uncompressed length valve spring. May cause coil bind if used with 1-3/4" spring, resulting in cam breakage. Also for 6hp-18hp single and twin cylinder flathead Briggs and Stratton engines exhaust valves.
    • Used Kohler part. $8.00 each, plus shipping & handling. (When available.)
    • OEM Briggs & Stratton part # 691939. $16.65 each, plus shipping & handling.
    • OEM Kohler part # 52 413 01-S. $17.65 each, plus shipping & handling.
  • High-Performance, Heat-Treated, Hardened Steel 7° Valve Spring Retainers. Use with high-performance single valve spring below Ê.
    • New. $12.00 per set of two, plus shipping & handling.
New 7° Valve Spring Keepers for 5/16" diameter valve stems. Fits all flathead cast iron block 6¼hp-16hp K-series and Magnum, 18hp/K361 OHV engines and KT series and Magnum twin cylinder flathead engines. Also fits 6hp-18hp single and twin cylinder Briggs & Stratton exhaust valves. Can be used with high-performance valve spring below Ê. Briggs & Stratton part # 494553; Kohler part # 41 755 10-S.
  • Aftermarket. $2.50 set of two (for one valve), plus shipping & handling.
  • OEM Kohler part. $6.35 set of two (for one valve), plus shipping & handling.
Replace worn lifters to prevent erratic valve action and premature cam lobe wear!

Valve Lifter (Tappet) for Kohler K-series and Magnum single cylinder flathead engine models K141 (6¼hp), K160 (6.6hp), K161 (7hp) and K181/M8 (8hp). Length: 1.964" for exhaust valve only and camshaft with automatic compression release (ACR). OEM Kohler part # 230013-S. Grind end of valve stems to set valve clearances.

  • New. $14.00 each, plus shipping & handling.

Valve Lifter (Tappet) for Kohler K-series and Magnum single cylinder flathead engine models K141 (6¼hp), K160 (6.6hp), K161 (7hp) and K181/M8 (8hp). Length: 2.020" for intake and exhaust valves and older two-piece camshaft without automatic compression release. OEM Kohler part # 232777-S. Grind end of valve stems to set valve clearances.

  • New. $14.00 each, plus shipping & handling.


Wide Base Lifters1" Base Adjustable Valve Lifter (Tappet) for Kohler K-series and Magnum single cylinder flathead engine models K241/M10 (10hp), K301/M12 (12hp), K231/M14 (14hp) and K341/M16 (16hp). Use for OEM stock or performance cams with up to .340" lift. OEM Kohler part # D-235327-S.

  • Used and in excellent condition. $15.00 each, plus shipping & handling.
  • New. $35.00 each, plus shipping & handling.

1.280" Base Adjustable Valve Lifter (Tappet) for Kohler K-series and Magnum single cylinder flathead engine models K241/M10 (10hp), K301/M12 (12hp), K231/M14 (14hp) and K341/M16 (16hp). For high-performance cams with .400"-.575" lift.

  • Used and in excellent condition. $15.00 each, plus shipping & handling.
  • New. $23.00 each, plus shipping & handling.

Adjustable Valve Lifter (Tappet) for Kohler engine models K482, K532 and K582. OEM Kohler part # D-277031-S.

  • New. $48.30 each, plus shipping & handling.


Valve Lifter (Tappet) for Kohler engine models KT17, KT17II, KT19, KT19II, KT21, MV18 (w/spec #'s 58560, 58561) and MV20 (w/spec #'s 57527, 57528). Used with serial number 1917809285 and before. 2.895" overall length. No longer available from Kohler. OEM Kohler part #'s 52 019 01-S, 52 019 02 -S. (The OEM manufacturers are phasing out many parts for flathead engines due to EPA smog emissions. But some parts may still be available in aftermarket.)

  • Used and in good condition. $10.00 each, plus shipping & handling.

Valve Lifter (Tappet) for Kohler engine models MV16, M18, MV18 (except w/spec #'s 58560, 58561), M20 & MV20 (except w/spec #'s 57527, 57528). Used with serial number 1917809286 and after. 2.885" overall length. OEM Kohler part # 52 019 03-S.

  • New. $15.25 each, plus shipping & handling.
Quality-Made, Heavy Duty, Scissors-Type Small Engine Valve Spring Compressor. NOTE: Designed to compress OEM stock, our medium- and high-performance valve springs, but not the double or extremely heavy single springs.
  • $25.00 each, plus shipping & handling.
Quality-Made, Heavy Duty, C-Type Small Engine Valve Spring Compressor. NOTE: Designed to compress OEM stock, our medium- and high-performance valve springs, but not the double or extremely heavy single springs.
  • $35.00 each, plus shipping & handling.
Quality-Made, Extreme Duty, V-Type Valve Spring Compressor. Safe and easy to use. Easily compresses double or extremely heavy single valve springs!
  • $15.00 each, plus shipping & handling.

Camshaft "Hair-Like" Compression Release Actuating Spring for Kohler K-series and Magnum single cylinder engine models K181/M8 (8hp), K241/M10 (10hp), K301/M12 (12hp), K231/M14 (14hp) and K341/M16 (16hp). OEM Kohler part # 47 089 01-S.
  • Used. $3.00 each, plus shipping & handling. (When available.)
  • New. $5.70 each, plus shipping & handling.
Camshaft Pins for Kohler K-series and Magnum models K141 (6¼hp), K160 (6.6hp), K161 (7hp) and K181/M8 (8hp) flathead cast iron block engines. Dimensions: .4365" diameter x 6-5/16" long. OEM Kohler part # 41 380 03-S.
  • Used, unworn and in excellent condition. (OEM Kohler.) $3.00 each, plus shipping & handling. (When available.)
  • New stress proof steel. $8.00 each, plus shipping & handling.
  • New OEM Kohler part. $19.50 each, plus shipping & handling.

Camshaft Pins for Kohler K-series and Magnum K241/M10 (10hp), K301/M12 (12hp), K321/M14 (14hp), K341/M16 (16hp) flatheads and K361 (18hp OHV) cast iron block engines. Dimensions: .499" diameter x 7" long. OEM Kohler part # 47 380 09-S.

  • Used, unworn and in excellent condition. (OEM Kohler.) $3.00 each, plus shipping & handling. (When available.)
  • New stress proof steel. $8.00 each, plus shipping & handling.
  • New OEM Kohler part. $14.70 each, plus shipping & handling.
Camshaft End Thrust Washers/Shims/Spacers for Kohler K-series and Magnum models K141 (6¼hp), K160 (6.6hp), K161 (7hp) and K181/M8 (8hp) flathead cast iron block engines. Dimensions: 7/16" i.d x 3/4" o.d.
  • .005" Thickness. OEM Kohler part # 230293-S. $3.20 each, plus shipping & handling.
  • .010" Thickness. OEM Kohler part # 230294-S. $3.20 each, plus shipping & handling.

Camshaft End Thrust Washers/Shims/Spacers for Kohler K-series and Magnum K241/M10 (10hp), K301/M12 (12hp), K321/M14 (14hp), K341/M16 (16hp) flatheads and K361 (18hp OHV) cast iron block engines. Dimensions: 1/2" i.d x 1" o.d.

  • .005" Thickness. OEM Kohler part # 275066-S. $4.00 each, plus shipping & handling.
  • .010" Thickness. OEM Kohler part # 275067-S. $4.00 each, plus shipping & handling.

And if you're wondering, all of Kohler's stock camshafts are removed by driving out the steel pin that it rides on from the PTO end of the block (opposite flywheel end) with a hammer and long steel pin that's slightly smaller than 1/2" in diameter. Also, there should be one or two shims on the pin. Be sure not to loose them. You'll need them when you reinstall the cam.

NOTE: The 18hp cam works great for more power in a 10hp and 12hp engines, but it won't do quite as much as the cubic inches increases. Although it will work great in the 14hp and 16hp engines, but it creates less noticeable power increase in the 14hp and especially the 16hp engine. However, it does help in the power increase in a 16hp, it's just less noticeable because of the bigger cubic inch displacement. A "mild-performance" cam, such as the 18hp cam, works better in engines with smaller cubic inches. A somewhat bigger cam is required as the cubic inches are increased. Because bigger engines needs to draw in and expel more air (at 4,000 rpm with stock valves), and the 18hp cam has it's limits when used in the bigger engines. And because of it's short lift and duration, it makes it's most power up to around 4,000 rpm.

NOTE: Use stock OEM valve springs with a stock OEM or 18hp cam if an engine is going to turn 4,000 rpm or below. And use Stock-Altered (single) valve springs for above 4,000 rpm. Because cast iron is brittle, do not use double (Super-Stock) valve springs with the 18hp or any [welded up] OEM camshaft! Also, with double springs, the compression release lever on the cam could break off. And be gentle when handling a cast iron camshaft! If the cam is mishandled, the lightweight spring that controls the compression release mechanism could come off the levers when installed in the engine. If this happens, the engine would crank over under full compression, making it very hard or impossible to start.

When having a camshaft reground, trust only places that use a specialized precision cam grinding machine. Because if the lobes are "hand ground" or if ground any other method, the cam may not work as well.

The cast iron camshaft that originally came in the Kohler model K361 18hp OHV engine is no longer available from Kohler. If you're lucky, you might find a new cam from old stock. The part number for this cam is 45 010 05S. They fit the 12, 14, 16hp flathead engines, too. Good for up to 4,000 rpm.) They work great in a stock engine!

The 18hp cam works great for increased power in a 10hp and 12hp engines, but it won't do quite as much in the 14hp and 16hp engine because of more cubic inches. Although it will work great in the 14hp and 16hp engines, but it creates less noticeable power increase in the 14hp and especially the 16hp engine. However, it does help in the power increase in a 16hp, it's just less noticeable because of the bigger cubic inch displacement. A "mild-performance" cam, such as the 18hp cam, works better in engines with smaller cubic inches. A somewhat bigger cam is required as the cubic inches are increased. Because bigger engines needs to draw in and expel more air (at 4,000 rpm with stock valves), and the 18hp cam has it's limits when used in the bigger engines. And because of it's short lift and duration, it makes it's most power up to around 4,000 rpm.

If you have a cam that was broke in two by a thrown connecting rod, save the tiny (hair-like) actuating spring from the compression release mechanism. It can be used on another cam that may not have one.


Differences in Various Cast Cams for Basically Stock Engines
(BBDC = Before Bottom Dead Center; ATDC = After Top Dead Center; BTDC = Before Top Dead Center; ABDC = After Bottom Dead Center)
Camshaft OEM Kohler 10hp, 12hp, 14hp & 16hp Flathead Cams (Average) OEM Kohler 18hp OHV Cam Reground 4,000 rpm Torque Cam
Exhaust Opens, Degrees BBDC 50° 50° 60°
Exhaust Closes, Degrees ATDC 20° 25° 36°
Intake Opens, Degrees BTDC 30° 52° 40°
Intake Closes, Degrees ABDC 70° 79° 80°
Overlap, Degrees 50° 77° 76°
Exhaust Duration, Degrees 250° 255° 276°
Intake Duration, Degrees 280° 311° 300°
Maximum Lift, Exhaust .301" .306" .311"
Maximum Lift, Intake .308" .325" .317"
Recommended Lash Settings
Exhaust .017" .017" .014"
Intake .008" .008" .009"


Setting the Valve Timing For Cast Iron Kohler Cams Without a Machined Adjustable Gear -

If you're planning to use a factory stock cast iron cam (such as a reground Kohler cam or the 18hp OHV Kohler cam), or if the cam grinder person ground your high-performance cast cam "right on the specifications," it shouldn't need to be degreed in. Just install it in the engine, usually along with a thin and thick shim (.005" & .010", respectively) toward the flywheel end, and it should be set pretty close to specs, if not right on it. But steel cams with an adjustable gear will probably need to be degreed in according to the provided specs sheet. Install shim(s) with a steel cam only to prevent wear on both the camshaft and engine block. To accurately set the valve timing on a Kohler or virtually any 4-cycle engine, simply align the punch [timing] mark on the camshaft gear, which is located between two gear teeth, with the groove or [timing] mark on or next to the crankshaft gear, which is located at one gear tooth.

If there's no timing marks on the crank or cam gears or if there's multiple marks on either gear (these can be confusing), to set the correct crank to cam timing on virtually any engine, automotive or small, with the crankshaft installed in the block, position the piston at true Top Dead Center (TDC). (True TDC is when the piston is at the very top of the cylinder.) If it's a multi-cylinder engine, use the #1 cylinder only for the piston and valves described in this paragraph. Install the camshaft and valves (or lifters if the engine is OHV), and then check for correct crank to cam gear teeth alignment by rotating the crankshaft so the piston is at true TDC on the exhaust stroke. Now slightly rotate the crankshaft back and forth by hand. When one valve opens (or lifter raises) slightly and the other valve closes (or lifter lowers) slightly, and vice-versa, and when the piston is either slightly before or after TDC while rocking the crankshaft, this is when the valve timing is set correctly. On the exhaust stroke, neither valve (or lifter) should be fully closed (or lifter resting on the base circle of the cam lobe) when the piston is at the TDC position. (This is called valve overlap.)

On a multiple cylinder engine, align the cam and crank gears with the piston in the #1 cylinder positioned at TDC on the compression stroke. On a twin cylinder engine, the #1 cylinder is the one closest to the flywheel. On an automotive engine, the #1 cylinder is the one closest to the front of the engine, or harmonic balancer. Align the cam gear tooth with the crank gear, and to check for correct cam to crankshaft alignment, rotate the crankshaft 180° so the #1 piston is at true TDC on the exhaust stroke. Then slightly rock the crankshaft back and forth by hand. One valve on the #1 cylinder should slightly open and the other valve on the same cylinder should slightly close. The piston should be either slightly after or before TDC while rocking the crankshaft, this is when the valve timing is set correctly.


Installing a Steel Camshaft that Has an Offset in the Center - (for long stroke engines)

Installing The Camshaft Pins Retaining ScrewsWhen installing a steel camshaft that requires two separate support pins, you'll need to cut a Kohler pin in half. But first measure the depth of the pin holes in the cam and the engine block to determine each pin length. Then drill the pin hole that's in the PTO end of the engine block to 1/2" diameter. To retain the pins in the block and to keep them from turning with the cam, a diagonally drilled hole must be made and some 1/4-20 threads must be cut, then tighten an Allen head set screw into each threaded hole to retain the pins. Be sure to apply Clear RTV Silicone Adhesive Sealant on the PTO end pin to keep oil from leaking out, too. Also, don't forget to drill and tap some 1/4-20 threads into the end of each pin so a 1/4" bolt can be threaded into them so they can be removed from the block later. By the way - I've always preferred to use Clear RTV Silicone Adhesive Sealant for two reasons: being it's an adhesive, it bonds parts together, forming a leak-proof seal; and being it's clear, it makes for a clean and professional-looking repair job. It can't be seen between the parts.

To install needle bearings in a block for a camshaft that will accept them, the holes for the cam pin will need to be precision bored (enlarged) to .6875" (11/16") in a milling machine exactly dead center. The exact dead center of the holes are found by using a centering indicator. If the holes are bored off-center just a few thousands of an inch, the cam and crank gear teeth won't mesh correctly and the lifters will wear the cam lobes prematurely. By the way - the needle bearings that's in Kohler's balance gears will work perfect for a cam that requires them.


Steel cam with an adjustable gearAlways degree in a high-performance steel cam to get maximum power from it. Why is this so important? Timing of the valves in relationship to piston travel plays a huge role in how well an engine performs. The key to accurate cam timing is to find exact Top Dead Center (TDC). The best method to find TDC is to use a degree wheel, dial indicator with a magnetic base, and a flat bar type of piston stop tool.

A maximum of 3.500" stroker crank can be used with the pin-through type of cam. For a longer stroke, the two-pin steel cam must be used.


Tools Needed to Dial In (or Degree In) a Billet Steel Camshaft -

Degree Wheel

The degree wheel is a round disc (usually made of aluminum) with the facing edge marked off in degrees, similar to the markings on a protractor. When used in conjunction with a dial indicator, it's installed on the crankshaft during the engine build to degree the cam in and check for correct valve timing events. It can also be used to check for accurate ignition timing. When in use, a degree wheel is fastened to the front of the crankshaft (automotive engines) or flywheel end (small engines). If it's fastened to the PTO end, it will need to face the engine block and be read from that position. Degree wheels can be purchased off of eBay.

Dial Indicator and Magnetic Base

A dial indicator is necessary to check for correct valve timing to tell precisely when a valve starts to open and the moment it closes. This opening and closing is very critical for high-performance engines and cannot be done by feel or by sight. A dial indicator can also be used to set accurate ignition timing in relation to piston travel. Each mark on the face of a dial indicator represents one thousandth of an inch (.001") graduations. The marks with a number (10, 20, 30, etc.) represents every ten thousandths of an inch (.010", .020", .030", etc.). A dial indicator always mounts on top of the engine block. Dial indicators are very precision and delicate instruments. Care must be used in handling one. Dial indicators can be purchased from LittleMachineShop.com.

Piston Stop Tool

A piston stop tool is used to accurately find the piston's true Top Dead Center (TDC). For a multi-cylinder engine, the piston stop is always used on the #1 piston, which is closest to the front of the engine block.

To make a simple piston stop for a flathead engine, if the spark plug is perpendicular with the head, an old, long-reach (long threaded) spark plug can be used in the head for a bump-stop. Simply position and fasten the head on the block with the plug directly over the piston. The spark plug can be adjusted up or down to find the top dead center of the piston in relationship with the degree wheel. A steel rod may need to be welded on the end of the plug for an extended reach.

Or for a universal flat bar type of piston stop, the bracket part should be made of minimum 1/4" thick x 1" wide flat steel or aluminum, drilled with a couple of holes so that it can be fastened to the top of the block with a couple of head bolts, directly over the piston. A minimum 1/4" bolt with a jam nut, threaded upside-down into the bracket is also required. The adjustment of the bolt is used to "stop" the piston. If a piston pops out of the cylinder at TDC, then to use a piston stop, install several spacers (flat washers) between the piston stop and engine block so the bracket will clear the piston and go past the TDC mark.

Advancing or Retarding a Steel Camshaft with an Adjustable Gear: (The paragraph below Ê was copied and pasted from Vogel Manufacturing.)

Adjust at the gear (loosen the (4) four clamping bolts) by moving approximately 5° in either direction. To return to position as ground, line up the ¼" dowell hole in gear with the ¼" dowell hole in cam face and insert ¼" dowel. As a reference point, .020" movement at the cam flange O.D. is 1° cam movement or 2° crank movement. Remember, degree in a camshaft with no lash and no installed springs.

Failure to accurately degree in the camshaft can effect how an engine performs. Proper valve timing quickly becomes a crap shoot without a degree wheel. Published valve timing is only a suggested starting point based on dyno testing and track experience. There are variables that may call for different valve timing in your specific combination. If you don't know where your valve timing is then the cam grinder or engine builder cannot recommend changes to help you get the most out of your engine.

Now is a good time to mention that while your cam grinder or engine builder should be able to supply you with a cam appropriate for your application, it will be necessary in most cases to change jetting and fine tune the cam timing and lash settings to the operator's preference and ability. The cam grinder or engine builder cannot know about the rpm ranges in your application without good accurate information on which to base his recommendations.

There are two easy ways to change the characteristics of your cam. Advancing and retarding the cam can move the power band up or down a few hundred rpm. Advance for more bottom end and retard for more top end. It usually takes about a 4° change to feel it. The second way is to change the valve lash. Tightening the lash will increase the top end power while loosening it will increase bottom end power. You won't hurt anything by tightening the lash but check with your cam grinder as to the maximum lash you can use before running off the ramp and damaging the valves. When making these changes, increases at one end mean decreases at the other end.

Valve opening and closing times are measured by the number of degrees of crankshaft rotation that takes place before or after what is called the piston's Top Dead Center (TDC) or Bottom Dead Center (BDC) positions. A piston is at TDC when it is at its highest point in the cylinder and at BDC when at its lowest point. The intake valve opens before the piston reaches TDC (which is BTDC) on the exhaust stroke and closes after the piston passes BDC (which is After Top Dead Center or ABDC) on the intake stroke. While the exhaust valve opens before the piston reaches BDC (BBDC) on the power stroke, it closes after the piston passes TDC (ATDC) on the exhaust stroke.


Names of Different Areas of the Cam Lobes
Names of Different Areas of the Cam Lobes

To find how much lift any particular cam has, using a micrometer or dial caliper, measure across the base circle of one lobe and then measure from the base circle to the toe of the same lobe, and then divide the difference. The answer will be the amount of lift each lobe has.


How to Dial In (or Degree In) a Steel Billet Cam for a Kohler Engine -

  1. Use a pencil, paper and arithmetic for this procedure, to keep track of the results. Pencil and Paper
  2. Install the valves, lifters, camshaft, crankshaft and front bearing plate in the engine. Make sure that the timing marks on both the cam gear and the crank gear are aligned. With the piston on the compression stroke and both valves fully closed, set the valve lash at zero for both valves. Install some stock valve springs to ensure that the valves will be in the fully closed position, and for a more accurate reading. Make sure the ends of the lifters and valve stems are ground square for proper adjustment!
    NOTE: If there's no timing or alignment marks on the gear teeth on the engine you're reassembling, then the to align or time the camshaft with the crankshaft is with the piston positioned at TDC and both lobes on the cam at BDC or pointing downward. Then, install the valves in the block. Rotate the crankshaft until the piston is at TDC on the compression stroke. The valves should be fully closed. If the piston is on the exhaust stroke at TDC, each valve should be open slightly. And if you "rock" the piston up and down slightly with it on the exhaust stroke, one valve should close and the other should slightly open and vice-versa.
  3. Fashion a rigid pointer from stiff wire or an old coat hanger and attach it to the engine block. This pointer locates the degrees on the degree wheel.
  4. With the degree wheel installed on the flywheel end of the crankshaft, rotate the crank to get the piston at TDC and check to ensure that the valves are fully closed then adjust the pointer to zero (0º TDC) on the degree wheel.
  5. Turn the crankshaft opposite the running rotation approximately 15-20°. Install a piston stop on the top of the engine block fastened in place by two head bolts.
  6. Continue to turn the engine in the same direction until the piston comes back up and just touches the piston stop. Make a note of the exact number on the degree wheel that the pointer is on.
  7. Rotate the engine in the other direction (running rotation) until the piston comes back up and touches the piston stop. Again note the number where the pointer is.
  8. Remove the piston stop and rotate the crankshaft to the midpoint of the two marks. At this point the piston is at the true top dead center. Loosen the degree wheel and adjust it so it will read 0º TDC at the pointer. Don't rotate the crankshaft to do this!
  9. Now, it's time to locate the lobe centerline relative to TDC. Attach the dial indicator's magnetic base on the top of the engine block. Set the tip to contact the top of the intake valve. Check to make sure that the indicator plunger is parallel to the valve stem. NOTE - any variance in an angle will produce geometric errors in the lift readings.
  10. Rotate the crankshaft in the normal direction (the direction in which the engine cranks over to start it) until maximum lift of the intake lobe on the cam is reached. Maximum lift is attained when the dial indicator starts to change direction. At this point reset the dial indicator to zero.
  11. Now turn the crankshaft in the normal direction until the indicator reads .050" before maximum lift. Make a note of the number on the degree wheel.
  12. After that reading, continue to rotate the crankshaft in its normal direction until the indicator goes past its zero setting to .050" on the closing side of maximum lift. Again, record the reading.
  13. Add the two numbers and divide the answer by two. This number is the location of maximum lift of the intake lobe relative to the crank and piston (a.k.a. the intake centerline). Check the cam spec card and it should confirm the settings. If it doesn't, remove or install end-play shims or adjust the cam gear as necessary.

By the way, I wish the people who custom grind and sell high-performance adjustable steel cams would include detailed instructions in their packages on how to set the cam timing. It's not right for me to have to try to explain it to everyone. Because I'm not making any money off any of my pulling tips.

See this web site for additional information for degreeing in a single cylinder engine camshaft: http://www.compgoparts.com/Support/Tutorials/CamshaftDegreeing.asp


Why Engines Need an Automatic Compression Release (ACR) -

The reason automatic compression release (ACR) is installed on small engines nowadays is because the engine has fixed (non-adjustable) advanced ignition timing. If it didn't have an ACR, under full compression, with fixed advanced timing, and at cranking speed, the engine would "kick back" when attempting to start it. "Kick back" occurs when the flywheel/crankshaft suddenly and violently rebounds or momentarily rotates in the opposite direction, which is could bend or break the starter armature shaft or the aluminum starter housing. By relieving about half the compression pressure in the combustion chamber, this allows the engine to crank over easier and start much quicker. A smaller starter motor and battery can be used.

If the engine kicks back too many times, this could bend or break the armature shaft, or break the aluminum casing in the gear starter!

On some older engines and virtually all automotive engines, at cranking speed, the ignition timing is positioned at 0° TDC, and with a (mechanically- or electronically-controlled) automatic timing advance, the engine starts easily under full compression, then the timing automatically advances to where it needs to be so the engine will produce full power. These engines require a high-torque starter motor and bigger battery.

An Easy Way to Start an Engine under Full Compression and with Advanced Ignition Timing with No Automatic Compression Release to Prevent "Kick Back":

With the timing permanently set in the advanced position, two separate electric switches will need to be used - one being a push button to crank the engine (with a gear starter), and the other being an ordinary OFF/ON toggle switch to power the ignition. To make this work, first crank the engine to get it spinning over (if the starter motor is strong enough), choke it, and then flip the ignition (toggle) switch to "put the spark to it." Doing this will allow the engine to start easily every time. Because the energy stored in the spinning weight of the heavy flywheel makes it impossible for the engine to momentarily "kick back" under full compression with no [advanced] spark. This starting method is also recommended for pulling engines (with points or crank trigger ignition) having a high-performance camshaft and no compression release.

How the Automatic Compression Release Mechanism Operates -

The ACR mechanism consists of two flyweights and a spring attached to the gear on the camshaft. When the engine is rotating at low cranking speeds (600 rpm or lower), the flyweights are held inward by a small spring in the position shown in the 1st drawing to the right, resulting in an effective compression ratio of about 2:1 during cranking.

After the engine speed increases above 600 rpm, centrifugal force moves the flyweights outward (in the position shown in the 2nd drawing to the right). In this position, the tab on the larger flyweight drops into a recess in the exhaust cam lobe. When in the recess, the tab has no effect on the exhaust valve and the engine operates at full compression to produce full power.

Performing a Compression Test on an Air-Cooled Gas Engine -

The compression relief is a mechanical swing arm on the cam. At cranking speeds, it holds the exhaust valve open about .050" to relief about half the compression so the engine will start easier. Because no engine can start under full compression with advanced ignition timing. When the engine starts, the increased rpm or centrifugal weight opens the swing arm so the exhaust valve will have 100% contact with the seat, allowing the engine to run under full compression.

The compression relief mechanism on the camshaft relieves about half of the compression pressure in the combustion chamber at cranking speeds. When the engine starts, the compression builds up to 100%. On OEM camshafts with a working compression relief mechanism and if the valves are adjusted to specs, the compression relief relieves about half the compression from the combustion chamber at cranking speeds. So when performing a compression test (with a gauge) on an air-cooled engine, keep in mind that, depending on how the engine is built, the compression ratio or the compression pressure can vary a lot from one engine to another. It depends on the size of the bore and stroke, if the head is milled flat or milled out for high lift valve clearance, if the camshaft has a compression relief or not, how much duration the cam has and the valve head diameters. When performing a compression test on a 10hp Kohler engine, it can range anywhere from 98 to 150 psi. On a 12hp, it can be from 112 to 170 psi. On a 14hp, it can range from 120 to 190 psi. And on a 16hp, it can be from 127 up to 192 psi. But as an engine wears, the compression will become less.

And cranking speeds, a long duration cam will relieve some of the combustion chamber pressure, resulting in a lower than normal reading. The more the duration, the lower the reading. To obtain an accurate compression pressure reading, perform the test with a fully charged battery and the throttle in the wide open position. Now perform the test. Then calculate the reading with the duration of the cam in the engine against the duration of a stock OEM cam. Example: If the compression pressure is 100 psi, I multiple 100 by 285 (duration of cam that's in the engine) and then I divide the answer by 223° (duration of a stock OEM cam), which gives me 128 psi. And if a cam has a compression relief mechanism, the compression reading will be cut in half.


NOTE - Cam technology is always advancing! What works for one engine won't necessarily work for another. Therefore, if you're wondering which cam profile will work best for your particular engine, it really depends on how many rpm the engine is going to turn. If it's going be governed at 4,000 rpm, then perhaps an 18hp OHV cam will work fine. But if it's going to turn faster, then a cam that's designed for a Stock-Altered or Super-Stock engine should be used. It's best to talk to a professional cam grinder person to determine which cam would benefit your engine best so it'll produce maximum rpm, power and torque.


Exhaust Header Pipe - Top of page

If you've ever had an engine with a stubborn or rusted exhaust elbow pipe fitting that's threaded-in-the-block, then you probably already know how much of a pain it is to remove. Well, this is how to remove the fitting if enough of it is protruding from the exhaust port:

  1. Apply penetrating oil to the pipe fitting threads and exhaust port. Gunk Liquid Wrench works great for this!
  2. Firmly clamp the engine block in a hydraulic press or place it under a heavy vehicle. (Do this only to secure the block in place.)
  3. Use a large adjustable plumber's pipe wrench to remove the fitting. Rotate it counter-clockwise to loosen it. If the pipe wrench alone won't loosen it, slide a ±3 foot long steel tubing on the pipe wrench's handle for added leverage. And don't worry, the block shouldn't crack or break when loosening the fitting.
  4. If the fitting breaks off flush with the block when attempting to loosen it, use a reciprocating saw (saw-saw) with a metal cutting blade to cut through the threads of the fitting (make several cuts in the fitting if necessary), and then chisel it out to collapse the threads. Chisel only where the metal [in the block] is thick to avoid breaking off part of the exhaust port.
  5. After the fitting is removed, if the threads are going to be used, clean and straighten them with an NPT tap of the appropriate size. A new fitting can now be installed. Or, if the engine is going to be used for competition pulling, grind out the threads and install a professional exhaust header pipe as shown below Ê.

Advertisement:
If you need a complete exhaust header pipe kit that's ready to bolt on, please contact A-1 Miller's Performance Enterprises | 1501 W. Old Plank Rd. | Columbia, MO 65203-9136 USA | Phone: 1-573-256-0313 (home/shop) | 1-573-881-7229 (cell/text). Please call Monday-Friday (except Holidays), 9am to 5pm, Central time zone. If no answer, please try again later. (When speaking with Brian, please be patient because I stutter.) Fax: 1-573-449-7347. E-mail: pullingtractor@aol.com. Send a message with Yahoo Messenger: | Directions to our shop | Yahoo! Maps, 1501 W. Old Plank Rd., Columbia, MO | 1501 West Old Plank Road, Columbia, MO - Google Maps or Map of 1501 West Old Plank Road, Columbia, MO by MapQuest. Click here for more parts and services. | NOTE: To place an order, please call or send an email with a list and description of the parts or services you need. Because as of right now, we're not set up to accept orders through our web sites online. Due to the rising cost of... everything, prices are subject to change.
If two 5/16" bolt holes needs to be made in the exhaust port for mounting the header pipe flange, this should be performed by an experienced machinist with the engine block bolted to a fabricated angled fixture securely fastened on the table of a large milling machine to drill the holes precisely in the exact locations. The holes are to be drilled with a 17/64" or letter "F" drill bit, at about 1-1/4" depth. Then the threads can be cut perpendicular to the exhaust flange with a (preferably new) 5/16-18 NC tapered tap. Use thread cutting oil and go slow when cutting threads in cast iron to prevent from breaking the tap off in the block. Because if it breaks off, it'll be extremely hard to remove! (It'll be the beginning of a nightmare!)

A-1 Miller's Repair Service: Professionally drill and tap two 5/16"-18 NC holes in the exhaust port for your block to mount exhaust header pipe below Ê. $40.00 labor, plus return shipping & handling.

Exhaust Header Pipe Kit for Kohler K241/M10, (10hp), K301/M12 (12hp) or K321/M14 (14hp) Stock, Hot-Stock, Stock-Altered or 30 c.i. engines with stock size or oversize valves and with or without a working governor.

Kit includes one 1-3/16" i.d. x 1-5/16" o.d. pipe; measures approximately 7" from the block and approximately 19" tall; has a 90°, 4" radius mandrel bend; mounting flange; two stainless steel Allen head (5/16-18 NC) mounting bolts and an anti-vibration brace. Galvanized-coated steel. Very shiny, resists rust and won't discolor from extreme exhaust heat. Designed for use on Cub Cadets and some other makes & models of garden tractors with a 10, 12 or 14hp Kohler K-series or Magnum engine. This pipe has a flange that securely fastens to the engine block with two furnished 5/16" diameter coarse thread Allen head bolts. If your block don't have the two threaded mounting holes, then they will need to be drilled and tapped to accept the flange. There is no other way to fasten this pipe to the block. No gasket is required. Use Clear RTV Silicone Adhesive Sealant instead because exhaust heat has no effect on it, it allows the two metals to have full contact so the bolts won't loosen. Plus, it makes for a professional-looking job because it can't be seen.

. The flange is also small enough to clear the governor lever. Shipping weight is 4 lbs.

  • Header pipe alone, with 90° bend. (No flange or anything else included.) $15.00, plus shipping & handling.
  • Header pipe with flange, but not welded. Anti-vibration brace included. (No hole drilled in brace): $30.00 each, plus shipping & handling. NOTE: You may need to locate and drill the hole in the brace to fasten to the head bolt.
  • Complete and ready to bolt on header pipe kit with flange welded-on and anti-vibration brace included: $40.00 each, plus shipping & handling.

Exhaust Header Pipe Kit for Kohler K341/M16 (16hp) Stock, Hot-Stock, Stock-Altered, Missouri Super-Stock or 50.5 ci Modified engines with stock size or oversize valves and with or without a working governor.

Kit comes with a 1-3/8" i.d. x 1-1/2" o.d., pipe; measures approximately 7" from the block and approximately 19" tall; 90°, 4" radius bend; mounting flange; two hex head stainless steel mounting bolts with flat washers and an anti-vibration brace. 16 gauge galvanized-coated steel. Very shiny, resists rust and won't discolor from extreme exhaust heat. This pipe has a flange that securely fastens to the engine block with two furnished 5/16" diameter coarse thread (5/16-18 NC) bolts. Requires no adapter. If your block don't have the two threaded holes, then they will need to be drilled and tapped to accept this pipe. There is no other way to fasten this pipe to the block. No gasket is required. Use Clear RTV Silicone Adhesive Sealant instead because exhaust heat has no effect on it, it allows the two metals to have full contact so the bolts won't loosen. Plus, it makes for a professional-looking job because it can't be seen. Designed for use on Cub Cadets and some other makes & models of garden tractors with a 16hp Kohler K-series or Magnum engines. Shipping weight is 4 lbs.

  • Header pipe alone, with 90° bend. (No flange or anything else included.) $10.00, plus shipping & handling.
  • Header pipe with flange, but not welded. Anti-vibration brace included. (No hole drilled in brace): $25.00 each, plus shipping & handling. NOTE: You may need to locate and drill the hole in the brace to fasten to the head bolt.
  • Complete and ready to bolt on header pipe kit with flange welded-on and anti-vibration brace included: $40.00 each, plus shipping & handling.
Steel header pipe mounting flange for Kohler K-series and Magnum engine models K141, K161, K181/M8, K241/M10 (10hp), K301/M12 (12hp), K321/M14 (14hp) single cylinder, and KT17, KT17II, KT19, KT19II, M18 and M20 twin cylinder. Approximately 3/16" thickness, (2) 5/16" diameter mounting holes spaced 1-3/4" apart, 1-5/16" center hole. No gasket is required. Use Clear RTV Silicone Adhesive Sealant . Plus, it makes for a professional-looking job because it can't be seen.silicone sealant. NOTE: Two 5/16-18 NC threaded holes must be drilled and tapped in the exhaust port to accept this flange.
  • $10.00 each, plus shipping & handling.

5/16-18 NC Allen head bolts for above È flange.

  • $2.00/set of 2, plus shipping & handling.
Steel header pipe mounting flange-to-engine block for Kohler K-series and Magnum engine models K341/M16 (16hp). 1/4" thick, (2) 5/16" oblong mounting holes spaced 2-1/4" apart, 1-1/2" center hole. To be welded onto a 1-1/2" o.d. pipe. Fits 16hp Kohler K-series and Magnum flathead engines and adapter below Ê. No gasket is required. Use Clear RTV Silicone Adhesive Sealant. NOTE: Two 5/16-18 NC threaded holes must be tapped into exhaust port of engine to accept this flange.
  • $15.00 each, plus shipping & handling.

5/16-18 NC stainless stain hex-head bolts with flat washers for above È flange.

  • $2.00/set of 2, plus shipping & handling.
Steel header pipe mounting flange-to-cylinder head for Kohler K-series engine model K361 (18hp OHV). 1/4" thickness, (4) 5/16" diameter mounting holes spaced 1-1/32" apart, 1-1/2" center hole. No gasket is required. Use Clear RTV Silicone Adhesive Sealant.
  • $20.00 each, plus shipping & handling.

5/16-18 NC Allen head bolts for above È flange.

  • $4.00/set of 4, plus shipping & handling.
Header Pipe U-Bolt Clamp for our 1-5/16" and 1-1/2" o.d. pipes. 5/16" diameter U-bolt w/13 gauge saddle. Use to fasten header pipe to anti-vibration brace to prevent breaking of pipe from mounting flange due to normal engine vibration while pulling.
  • $2.50 each, plus shipping & handling.


Steel spacer for mounting anti-vibration brace with recessed cylinder head bolt that's closest to exhaust port. A longer bolt or threaded stud must be used. Dimensions: 13/32" i.d. x 3/4" o.d. x 5/8" height. Replaces Kohler part # X-400-71-S. (Discontinued from Kohler.)
  • $2.00 each, plus shipping & handling.


A-1 Miller's Performance Enterprises Offering Quality Products and Professional Workmanship at Reasonable Prices!

à Return to Main Pulling Tips Page | Return To Previous Page | Reputable Garden Pulling Tractor Engine Builders, Parts Suppliers and Service Providers | Miller's Garden Pulling Tractor Picture Gallery | Pulling Sled for Garden Tractors Picture Gallery | Classified Advertisements for Garden Pulling Tractors, Related Parts & Pulling Event Announcements | Hot Links for Various Garden Tractor Pulling Clubs and Associations | Top of Page

© 1996-Present. Designed and maintained by Brian Miller.