Information
about Valves, Seats, Porting, Camshaft and Exhaust Header Pipe
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If your engine is hard to start (cranks over too easy) or it loses power after running it for a while, then chances are it probably needs a valve job performed. As the valve face(s) (and seats) wear, this takes up the required clearance between the valve stem and lifter, preventing the valves from fully closing, sealing in the compression. Also, most valves nowadays in engines are made of recycled metal. When they get hot, they stretch. This decreases the required gap or clearance between the lifters and valve stem for the valves to fully close on the compression stroke and seal in the compression.
If an engine is losing power, and new ignition components were installed and the ignition timing is set correctly, and the carburetor was professionally rebuilt, then chances are the valves are leaking. It probably needs a professional valve job performed. We get a lot of engines in our shop that need a valve job. Many other repair shops will ignore the valves (or they're not trained to perform valve jobs) and assume the problem is elsewhere in the engine.
To test for leaking valves, with the cylinder head removed and the piston at TDC on the compression stroke (both valves fully closed), spray WD-40 or an equivalent light liquid around each valve and then use compressed air to blow through the exhaust and intake ports. Wrap a rag around the air nozzle and place it snug against the port so full air pressure will be against the valve. If bubbles form around the valves when applying the air pressure, this means that the valves are leaking and a professional valve job is required.
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. 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.
If fuel sprays out of the carburetor on a twin cylinder engine when it's running at fast speed, then the following can cause this:
- The hole in the main jet of the carburetor was mistakenly enlarged when cleaning because it was clogged with debris.
- 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. The valve clearances needs to be reset, or a professional valve job needs to be performed.
- But if an intake valve isn't moving, 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 lifter, rusting it. While the engine is running, the rusted lifter wears the lobe until it's wore down or "rounded." This sort of thing will also prevent a single cylinder engine from revving up. Replacement of the lifters and camshaft is required.
How to Perform a Professional
Valve Job -
First of all, four tools are needed: valve spring compressor, valve grinding machine, valve seat grinder or cutter and valve lapping compound and valve lapping (spinning) tool. To do a lousy valve job, some people will just remove the valves, clean them thoroughly and then use valve lapping compound to reseal them to the seats and reset the lash. Doing this will help an engine to run better for a while, but it's not the correct way of doing a professional valve job. To do it right the first time and make the valves last a long time so the engine will produce power...
- First rotate the crankshaft until the piston is at top dead center (TDC). Or, rotate the camshaft (if the crank is already out of the block) until both valves are fully closed.
- After removing the crankcase breather, remove the valves using a valve spring compressor tool. Be sure not to lose the keepers! Put 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.
-
Remove
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.
- Inspect the valve face for wear, and measure the stem diameter for wear.
- Check the valve guides for wear. Most of the time, the exhaust guide will wear more than the intake. The maximum wear limit on the 7hp and 8hp engines is .005" for the intake,.007" for the exhaust. And on the 10hp, 12hp, 14hp and 16hp 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. A worn valve guide will cause an engine to pop out the exhaust at higher rpms.
-
If they're not burnt, bent or badly warped, used valves can be refaced on
a valve grinding machine at an automotive machine shop. But if they are damaged
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,
respectively. The reason there's a 1º difference is because as the valve
and seat wear together, they'll form a leak-proof seal.
NOTE: All of Kohler's valves come from the factory ground at a 45º angle, and the seats are ground at 46º. And there's no need for the valve seat contact area to be in the center of the face of the valve. (This is determined by lapping in the valves.) The valves will actually breath better at higher rpms if the seat contact area is towards the edge of the valve face. -
To perform a high-performance
valve job, grind a 30º angle on the face of the intake valve and
seat only, lap the valve(s) in their seats, and then cut away the metal
next to the lapping area and swirl-polish (smooth the metal) underneath the
intake valve head so more air/fuel will enter the combustion chamber. Because
any restriction of the incoming air through the intake opening won't allow
an engine to produce more power. The 30º angle plus the undercutting
and swirl-polishing will add approximately 15% more airflow at higher rpms,
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 the exhaust opening will cause an engine to lose power and possibly not
allow it to rev to its full potential at higher rpms. There's no need to
swirl-polish the underneath of the exhaust valve head.
-
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 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.
- 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 competitive pulling, set the valve clearances at .010" for the intake and .014" for the exhaust.
-
-
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.
- 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.
- 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.
-
After making the proper lash adjustments, remove the valves, and apply a
small quantity of valve lapping compound (available at most auto parts stores)
on each valve face and then
use
a valve lapping tool (also available at most auto parts stores) to lap the
valves in the seats (rotate each valve back and forth with the tool) until
the "grinding sound" goes away. This process is important. It seals the valves
in the seats.
-
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.
- 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.)
- 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.
- Reinstall the crankcase breather using new gaskets, and that's it! Return To Previous Web Page.
NOTE: Valve rotators rotates the valves slightly as they open to clean or "wipe" away any carbon deposits from the valve face and seat to prevent the valve from burning. Shorter valve springs must be used with rotators to prevent coil bind at full valve lift. And rotators can be used in any 10hp-16hp Kohler engine. They help the valves last longer.
| New valve spring compressors. Made in USA. If interested,
please contact: Brian Miller at A-1 Miller's Small
Engine (1501 West Old Plank Rd., Columbia, Missouri. 65203 | Phone:
1-573-875-4033). Please call any day between 12 noon and 8:00 p.m. Central
time, and please be patient because I stutter. Fax: 1-573-449-7347. You can
also contact me through Yahoo! Messenger:
|
||
New OEM Replacement Valves -
|
||
 Stock (centered)
cast iron valve guides NOTE: May need to be reamed after
installation.
For 7hp and 8hp K-series and Magnum cast iron block flathead engines. .310" i.d. x .5645" o.d. x 1.686" overall length. Replaces: Kohler 230007-S. $5.00 each, plus shipping. For 10-16hp K-series and Magnum cast iron block flathead engines. .310" i.d. x .629" o.d. x 2.135" overall length. Replaces Kohler part # 235007-S. $9.00 each, plus shipping. For flathead twin cylinder KT series and Magnum engines. Replaces: Kohler part # 52-316-02; 52-316-04; 52-316-06; 52-316-08; 52-316-08-S. $5.00 each, plus shipping. |
 Valve Spring Retainers (keepers).
Replaces: Kohler 41-755-10-S; 240013. Fits 5/16" diameter valve stems. Fits
7-16hp K-series and Magnum cast iron block and twin cylinder KT series and
Magnum flathead engines. Also fits 6-18hp single and twin cylinder Briggs
& Stratton engines. $4.00 set of two, plus shipping. |
|
| New scissors-type valve spring compressor for small engines. This tool
can easily compress high-performance double springs! Adjustable-width jaws.
Made in USA. $25.00 each, plus shipping.
|
New "C"-shape valve spring compressor for small engines. Comes with two
sizes of jaws for wide and narrow springs. Two jaw size; for springs 3/4"
to 1 1/16" diameter. Heavy-duty frame and screw for rigidity. For Briggs
and Stratton, Clinton, Tecumseh, Harley-Davidson, etc. Not recommended for
high performance double springs. Made in USA. $35.00 each, plus
shipping. |
New heavy duty "C"-shape automotive and small engine valve spring compressor.
This tool can easily compress high-performance double springs! Adjustable-width
jaws for narrow and wide springs. $45.00 each, plus shipping. |
 NEWAY Valve Seat Cutter Kit for most air-cooled small
engines. Comes with one 31° and 46° cutting head and necessary
1/4", 5/16" and 11/32" pilots. Can be used to narrow other angles. Has carbide
cutters to recut even the hardest valve seats. Hand operated. Ensures greater
accuracy and precision work. Made in U.S.A. Replaces (OEM): Briggs &
Stratton part #19237. Part No. 750-299. $300.00 each, plus shipping. |
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New intake valve for models K-141,
K-161, K-181, M8, 7hp and 8hp Kohler K-series and Magnum flathead cast iron
engines. Head diameter: 1-3/8"; length 4.065"; stem: .309"; face angle:
45°. Replaces Kohler part # 230008, 230008-S. $17.00 each, plus
shipping.
How to Fix a Loose Valve Seat in an Aluminum Flathead Block Engine or OHV Cylinder Head -
We've had engines in our
shop where a previous shop attempted to repair a loose valve seat by peening
it in place with a pointed punch. We found that this doesn't work most of
the time. We use a blunt punch and medium size hammer, and pound the aluminum
360° around the seat. The below is the professional way of doing it.
- The valve will need to be removed from the block or head.
- The loose seat will need to be peened back in place with a 1/4" blunt punch and medium size hammer or the ball end of a medium size ball-peen hammer. This 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 won't sit crooked in the block.
- 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.
Advertisement:
| If you have an engine with a loose valve seat, please contact me,
Brian Miller at A-1 Miller's Small Engine (1501
West Old Plank Rd., Columbia, Missouri. 65203 | Phone: 1-573-875-4033). Please
call any day between 12 noon and 8:00 p.m. Central time, and please be patient
because I stutter. Fax: 1-573-449-7347. You can also contact me through Yahoo!
Messenger:
Services include:
|
the
OHV 18hp K361 Kohler or Tecumseh OHV engines. (Install oversize o.d. valve
seat so the OEM valve can still be reused.): $40.00 each for parts
and labor, plus return shipping.
To perform a professional valve job, just cleaning the valves and then re-lapping them in, and then hope the engine will run fine for many years without problems. 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 alignment.
Modifying the Stock Valves and Seats for Improved Performance -
First of all, part of what makes an engine to produce power
is the valves and 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 rpms and more power.
By grinding the intake valve head thinner (grind away the underneath part)
and giving it a 30º angle instead of the factory 45º angle will
allow the valve to be lighter in weight even more. But leave the exhaust
valve 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.
To find the face-to-seat mating area, first enlarge and grind the seat angle and rework the valves as mentioned above. Then lap the valves in with valve 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.
FYI - The way I swirl polish the underneath side of a valve head is I chuck the valve stem in my drill press, turn it on slow, and then I hold a 1" diameter stone in my die grinder (with the die grinder turned on) against the head until it has a somewhat swirled surface. Then I polish the surface with #40 emery cloth until it's smooth.
There are two ways to remove metal from the underneath of the valve head:
- Remove the metal from the underneath of the valve head in a metal lathe.
- Chuck the valve in a handheld electric drill, then hold the underneath side of the valve head at a 90° angle to a spinning bench grinding wheel while spinning the valve in the opposite direction. It grinds faster this way.
- Either way produces excellent results.
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. That's when an engine makes a "sputtering" sound and/or sprays fuel out the carburetor at high speed.
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.
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". Either of these lifters are available from Vogel Manufacturing Company (http://www.vogelmanufacturing.com).
Installing Bigger Valves 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 25% larger than the originals. 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 competitive 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. All intake valves are made of mild steel. 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 will give about 40% increase in air flow. Lighten the head and swirl polish underneath the head to smooth the air flow, too.
On the intake valve side, for every 1/8" increase in diameter, about 1hp is added for a 4,000 rpm limit engine and 2-3hp is added for a non-governed/high-performance engine. Of course, the exhaust valve will need to be increased in size too, to quickly rid the combustion chamber of the burnt gases.
The approximate oversize valves have been found to work well in the following most popular Kohler engines:
- 10hp - 1.600" intake and 1.375" exhaust, when using a 1" bored-out #26 Kohler carburetor.
- 12hp (30 c.i.) - 1.800" intake and 1.500" exhaust, when using a large Mikuni carburetor.
- 12hp, 14hp and 16hp (37 c.i.) - 1.700" intake and 1.500" for the exhaust, when using a bored-out 1.2" #30 Kohler carburetor.
These sizes flows best according to the cubic inch displacement and 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 combustion chamber will need to be (for clearance around and above each 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 a big cam and proper valve timing are all matched correctly.
Remember, when enlarging the ports, especially the intake port, make it the same size as the carburetor throttle bore or a "bottle neck" will occur, and the engine will starve for sufficient air at high rpms.
Using a Small Block Chevy Intake Valve in a Kohler Engine -
Small block Chevrolet V8 and certain V6 engine stock intake
valves will work in a 10-16hp Kohler engine with excellent results, even
with offset valve guides. The 1.72" or 1.84" diameter intake valve [229/v6,
267, 283, 305, 307 and 327 cid engines] can be used for the intake in a 10-16hp
[pulling] engines, and for the exhaust only in a 16hp [pulling] engine. The
1.94" and 2.02" [4.3/v6, 305, 327, 350 and 400 cid engines] will work for
the intake in a 16hp/50+ c.i. [pulling] engine.
Stock intake valves works great in a pulling engine because the engine doesn't run long enough for the valve to burn.
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. For more accurate results, it's best to use a
bridge reamer. A bridge reamer has a taper that will enter an undersize hole
and then as the cut progresses, it cuts like any parallel reamer. If a reamer
isn't available, then use a 11/32" drill bit. A drill bit will produce the
same results as a reamer.
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 -
When
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 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 rpms. I know, I'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.
How to Remove Old Valve Guides -
FYI - Worn valve guides don't necessarily need to be removed. They can be repaired with thin-wall bronze liner guides, like the ones installed in automotive cylinder heads. This method would cost less & last a long time. But if you want to install new Kohler-type cast iron guides, here's how it's done:
- Remove the valves, springs and retainers.
-
On the 7hp (K141 & K161)
and 8hp (K181) flathead single cylinder and the flathead twin cylinder Kohler
engines, if the lifters (and camshaft) are installed, break half of the guide
off inside the valve spring compartment with a flat chisel and a medium size
hammer, and then use a long 5/16" diameter grade 8 bolt with a nut threaded
on the bolt, "round off" the hex shape of the nut with a grinder, and then
place the threaded end of the bolt in the guide 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, just drive the entire guide out into the valve spring compartment with a long 5/16" diameter grade 8 bolt with a nut threaded on the bolt and a big hammer.
- Install the new guide with the grade 8 bolt with a flat washer under the nut so the guide will bottom out with inside of the intake and exhaust port area.
-
The new guides may need
to be enlarged with a 5/16" reamer so the valve stems will have proper clearance.
For more accurate results, it's best to use a bridge reamer. A bridge reamer
has a taper that will enter an undersize hole and then as the cut progresses,
it cuts like any parallel reamer. If a reamer isn't available, then use a
5/16" drill bit. A drill bit will produce the same results as a reamer.
Installing Offset Valve Guides -
The
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.
For more accurate results, it's best to use a bridge reamer. A bridge reamer
has a taper that will enter an undersize hole and then as the cut progresses,
it cuts like any parallel reamer. If a reamer isn't available, then use a
5/16" drill bit. A drill bit will produce the same results as a reamer. There
are 3 ways to install new valve guides:
- If an engine is going to run stock diameter valves, and if the old guides are worn, or if you want to upgrade them for high-performance use, leave the OEM valve guides in the block, and have them center-reamed to accept a thin-wall bronze liner.
- For installation of oversized valves, install new guides that's made of 5/8" diameter solid bronze with an offset center hole.
- Or, for installation of oversized valves, install 5/8" diameter mild steel as a shell with an offset center hole, to accept a thin-wall bronze liner.
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
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.
How to locate where to machine the cylinder head for the valves...
- Strip the engine down to the bare block.
- Fasten the billet cylinder head and head gasket on the block with a couple of bolts.
- 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.
- 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 location for the center of the valve heads.
-
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 side clearance.
- 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...
- For the 10-16hp engines, set valves at their respective clearances. (See above.) 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.
- 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.)
- Place the head and gasket on the engine and tighten down a couple of head bolts.
- Rotate the engine slowly by hand 360°. If it stops rotating, do not force it! (Because a valve may get bent.) Remove the head and see if one of the valves is hitting the head.
- If the engine does rotate freely, and after rotating it 360°, remove the head and use the depth gauge on a dial caliper to check to see how much the clay has flattened out. The clay should have a thickness of about .070" minimum.
- Remove metal from inside head (valve cavities) as necessary to gain proper clearance.
- Clearance around the valves should be the same as above the valves (valve shrouding).
- 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.
For quality stiffer-than-stock valve springs, oversize valves, lightweight retainers and hardened keepers, contact Lakota Racing (http://www.lakotaracing.com), Midwest Super Cub (http://www.midwestsupercub.net) or Vogel Manufacturing Company (http://www.vogelmanufacturing.com). They offer light-weight valve springs that's stiffer than stock springs, but won't normally break a Kohler cast iron camshaft with a lift up to .432".
Advertisement:
| If you need valve work performed on your engine, please contact me,
Brian Miller at A-1 Miller's Small Engine (1501
West Old Plank Rd., Columbia, Missouri. 65203 | Phone: 1-573-875-4033). Please
call any day between 12 noon and 8:00 p.m. Central time, and please be patient
because I stutter. Fax: 1-573-449-7347. You can also contact me through Yahoo!
Messenger:
Services include:
|
For durable stainless steel or light-weight titanium stock-size and oversized valves, along with stiffer springs, heavy duty retainers and keepers, contact either Lakota Racing, Midwest Super Cub or Vogel Manufacturing Company.
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 rpms.
"Polishing" is when the intake and exhaust ports are made smooth so the atomization mixture of the air/fuel isn't interrupted. Polishing of the exhaust port also helps the exhaust gases to exit quicker from the engine. Actually, by leaving the intake port "rough" and not smooth, this will cause the fuel to atomize into smaller particles, and mix better with the air, allowing the engine to produce more power. But it's best to have exhaust port smooth so the escaping gases will exit the combustion chamber with less obstruction.
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.
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 the Camshaft and How to Degree in a Steel
Cam (Updated 07/07/01) Top of page
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 cams lift the valves higher and hold them open longer in relation to piston travel than stock camshafts. (This is otherwise known as "valve lift" and "duration.") Air is very flexible. It can be compressed as well as it can be expanded. So when an engine revs at high rpms, air doesn't have time to exit back through the valves, so it becomes trapped within the combustion chamber. In that way, more air/fuel mixture is drawn into the cylinder. This is what builds up the compression with a long duration cam so the engine will produce more power at higher rpms. In addition, a larger portion of the burned gases will be expelled from the engine. 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 wide base lifters with a cam that has a lot of lift and duration. Use of the right cam and proper valve timing can help an engine come to life and scream down the track!
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 isn’t 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. 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.
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 rpms. Here's some things an engine will also need with a big cam:
-
It'll
need bigger valves, stiffer-than-stock valve springs and wide base lifters.
- It'll need extensive porting and polishing.
- It'll need a much bigger carburetor than Kohler makes.
- It'll need a billet aluminum cylinder head for valve clearance.
- And it'll need a steel flywheel for safety.
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 rpms resulting in erratic valve action, and it'll
cause the ignition timing to be very erratic, which will cause the engine
to lose power. It'll even make the engine "pop" and backfire out the exhaust
at high rpms.
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.
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 rpms. 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.
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
6.6hp engines and the very early K241 10hp engines. 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 (or if updated with a gear starter) and 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. After the engine started, spring-loaded flyweights
on the cam gear would rotate the point lobe slightly, automatically advancing
the timing to 20° BTDC so the engine can produce full power. These cams
also have the same lift and duration of the newer, one-piece camshaft with
the automatic compression release mechanism.
If you decide to install or reuse this type of cam, when installing the cam in the engine block, make sure the timing marks on the cam gear and points lobe are aligned, or 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.
When setting the ignition timing 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 rotates slightly and automatically advances the timing to 20° BTDC. Don't set the timing at 20° BTDC (S mark) with this type of cam. Setting it at 20° BTDC will advance the timing too much and cause the engine to "kick back" when trying to start. 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 medium size hammer and a long steel rod that's
slightly smaller than 1/2" in diameter 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.
!
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 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, please contact
me, Brian Miller at A-1 Miller's Small Engine
(1501 West Old Plank Rd., Columbia, Missouri. 65203 | Phone: 1-573-875-4033).
Please call any day between 12 noon and 8:00 p.m. Central time, and please
be patient because I stutter. Fax: 1-573-449-7347. You can also contact me
through Yahoo! Messenger:
|
|
Used
genuine OEM Kohler one-piece cast iron camshaft with a working automatic
compression release for Kohler K-series 10hp-16hp K241-K341 and Magnum M10-M16
flathead cast iron engines. The points lobe, lifter lobes, gear teeth and
compression release tang are all in good condition. Kohler part # 47-010-09.
These are NOT 18hp cams, and I have no used 18hp cams available.
$40.00 each, plus shipping. [When available.]
If you want a more aggressive cam for a stock engine, please send your 10-16hp OEM flathead Kohler engine cam to me, Brian Miller, at 1501 W. Old Plank Rd., Columbia, MO 65203, and have it reground for increased duration with stock lift up to 4,000 rpm for $125.00, plus return shipping. This cam profile has the stock lift, will pass tech for stock cam, and it adds about 2-1/2 more horsepower to an average engine. When sending a cam to me, be sure to include a note with your name, mailing address, phone number and that you want the cam reground for increased duration up to 4,000 with stock lift.
|
Used governor gears for Kohler K-series 10hp-16hp K241-K341, 18hp K361
OHV and Magnum M10-M16 cast iron block engines.
|
New .499" diameter x 7" long
camshaft pin made of 1144 Stress-Proof Steel (95,000 p.s.i. strength) for
Kohler K-series 10hp-16hp K241-K341 and Magnum M10-M16 flathead cast iron
block engines. Replaces Kohler part # 47 380 09 S. $5.00 each, plus
shipping.
New
Needle Bearings for camshafts that require them. Dimensions: 1/2" i.d. x
11/16" o.d. x 1/2" width. $10.00 each, plus shipping.
Plastic Material: $6.00
each, plus shipping. Good for up to 4,000 rpms. OEM Kohler part # A235743S.
[When available.]
Cast Iron Material:
$20.00 each, plus shipping. These won't break at very high rpms.
No longer available from Kohler. [When available.]
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 rpms 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 tang 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
ground any other method, the cam may not work as well.
The OEM 18hp 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 may find a new cam from old stock some place else. The part number for the cam is 45 010 05S. Or you can send your 10-16hp OEM flathead Kohler engine cam to me, Brian Miller, at 1501 W. Old Plank Rd., Columbia, MO 65203, and have it reground for increased duration up to 4,000 with stock lift for $125.00, plus return shipping. This cam profile adds about 2-1/2 more horsepower to an average engine. When sending a cam to me, be sure to include a note that you want the cam reground for increased duration up to 4,000 with stock lift. List your name, mailing address and phone number, too. Or, contact Lakota Racing for a duplicate 18hp cam. Or a "Cheater" cam can be acquired from Vogel Manufacturing Company.
| Camshaft | OEM Kohler Flathead Engines (10hp, 12hp, 14hp & 16hp) Cams (Average) |
OEM Kohler 18hp OHV Cam |
Reground "Cheater" Cam |
| Exhaust Opens, Degrees BBDC |
50° | 50° | 60° |
| Exhaust Closes, Degrees ATDC |
20° | 25° | 36° |
| Inlet Opens, Degrees BTDC |
30° | 52° | 40° |
| Inlet Closes, Degrees ABDC |
70° | 79° | 80° |
| Overlap, Degrees |
50° | 77° | 76° |
| Exhaust Duration, Degrees |
250° | 255° | 276° |
| Inlet Duration, Degrees |
280° | 311° | 300° |
| Maximum Lift Exhaust, in. |
.301" | .306" | .311" |
| Maximum Lift Intake, in. |
.308" | .325" | .317" |
| Recommended Lash Settings | |||
| Exhaust, in. | .017" | .017" | .014" |
| Inlet, in. | .008" | .008" | .009" |
Setting the Valve Timing For Cast Iron Cams Without a Machined Adjustable Gear -
To set the valve timing, simply align the mark on the camshaft gear with the mark on the crankshaft gear. But if there's no timing marks, or if there's multiple marks (these can be confusing), on a single cylinder engine, align the crank and cam gears with the piston at Top Dead Center (TDC) on the compression stroke. If it's a multiple cylinder engine, use the #1 cylinder. TDC on the compression stroke is when both valves are fully closed and the piston is at the top of the cylinder. Then rotate the crankshaft 180° so the piston is at TDC on the exhaust stroke, and then rock the crankshaft back and forth by hand. When one valve opens and the other closes and vice-versa, and when the piston is either after or before TDC while rocking the crankshaft, the valve timing is set correctly.
If you're planning to use a factory stock cast iron cam (such as the 18hp OHV 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.
!
NEVER INSTALL A CAMSHAFT DRY! Always lubricate the cam and pin with motor
oil or grease before reinstallation! If this isn't done, 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!
Installing A Steel Camshaft That's Offset In the Center - (for long stroke engines)
When
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 some silicone sealer 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.
But if the cam requires needle bearings in the block, then the bearings that's in Kohler's balance gears will work perfect.
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. |
Always
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 and a piston stop. Or for
a piston stop, on a flathead engine, a long reach spark plug can be used,
and the cylinder head can be positioned it so the spark plug is over the
piston.
Tools Needed to Dial In (or Degree In) a Steel Billet Camshaft -
|
|
|
"
"Dial Indicator"
"Piston
Stop"
Check your local automotive parts supply stores for a dial indicator and degree wheel. If they don't have them in stock, they can probably order them for you. eBay is also a good place to find these items. But a piston stop will probably have to be fabricated from scratch, because they're not marketed for single cylinder engines. Or for a piston stop, on a flathead engine, a long reach spark plug can be used, and the cylinder head can be positioned it so the spark plug is over the piston.
Advancing or Retarding the Steel Camshaft: (The paragraph below 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
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.
Go here for Vogel's CAMSHAFT AND VALVETRAIN INFORMATION. (.PDF file.)
How to Dial In (or Degree In) a Steel Billet Cam for a Kohler Engine -
-
Use a pencil, paper and arithmetic for this procedure, to keep track of the
results.
-
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. - 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.
- 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.
- 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.
- 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.
- 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.
- 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!
- Now, it's time to locate the lobe centerline relative to TDC. Attach a dial indicator 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.
- 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.
- 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.
- 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.
- 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
How the Automatic Compression Release (ACR) 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 rpms 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 improving! 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 RPMs 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 rpms, power and torque. Professional engine builders are the ones that really should answer your questions about choosing the correct cam for your particular engine. If you're looking for a quality cam for your garden pulling tractor, or wondering which grind to use in your engine, contact Lakota Racing (http://www.lakotaracing.com) Midwest Super Cub (http://www.midwestsupercub.net), Vogel Manufacturing Company (http://www.vogelmanufacturing.com) or look in my advertisement web site or you can place a want ad in the same site for a cam.
For one of the best camshaft grinders around, fast and able to talk to all the time, contact Greg Hackman of Small Engines in Seymour, 726 E. Tipton St., Seymour, Indiana. Phone 1-812-522-4777. All of the top NQS engine builders use these cams. They are great people to talk to and are really knowledgeable about camshafts.
How to Fabricate an Exhaust Header Pipe (Updated 8/20/06) Top of page
First of all, if you've ever had an engine with a stubborn or rusted exhaust elbow pipe 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 those pipes if enough of it is protruding from the exhaust port:
-
Apply penetrating oil to the pipe's threads and exhaust port.
(
Gunk's Liquid Wrench works great
for this!)
- Clamp the engine block in a hydraulic press (only to hold it in place).
- Use a large adjustable plumber's large pipe wrench to remove the pipe. If the pipe wrench alone won't loosen it, slide a 3 foot long [water] pipe on the pipe wrench's handle for added leverage.
- If the pipe is broken off flush with the block, then it will need to be chiseled it out to collapse the threads. Chisel only where the metal is thick in the block, to avoid breaking the exhaust port!
- After the pipe is removed, clean and straighten the threads with an NPT tap. You can now install a new pipe.
Or, if you're going to build the engine for pulling competition, use a die grinder to grind away the threads, and then install a professional header pipe as described below.
Items
needed to fabricate an exhaust header pipe are:
- Use either aluminized steel or stainless steel automotive exhaust tubing. Pipe size is 16 gauge 1-1/2" o.d. (for the 10hp, 12hp and 14hp engines) and 1-3/4" o.d. (for the 16hp engines) x 24" [overall] in length. NOTE: Stainless steel is more durable due to normal engine vibration at high rpms. Be sure to acquire some 304 alloy stainless steel that's recommended for use in pipe bending machines. Another note: Mandrel-bent pipes are when the elbow section is the same diameter as the rest of the pipe. (To prevent the bend area from being reduced in diameter, special "saucer-shaped" discs are placed inside the pipe at the bend area before the actual bending is performed.)
-
Minimum 1/4" thickness flat steel for use as the mounting flange.... Drill
two mounting holes in the flange so they'll match the holes in the adapter.
(Read below).
-
Adapter for the 10, 12 and
14hp engines only....
Because the exhaust port is much smaller on these engines, an adapter that goes between the mounting flange and engine block must be fabricated. The adapter is rectangular in shape; 2" x 3" x 3/4" in thickness, with a 1-1/4" hole, two diagonally drilled holes that's spaced 1-13/16" apart and two holes that's spaced. Note: The adapter may interfere with the operation of the governor lever. If it does, then modification of the lever may have to be made. Because part of the adapter extends over where the lever is, the governor lever will have to be reworked to make clearance for the adapter.
NOTE: The 10, 12 and 14hp engines need an adapter because the pipe's mounting flange is too large to be bolted directly to the engine's exhaust port. - Flange for the 10, 12, 14 and 16hp engines - 2-3/4" o.d. with a 1-1/2" hole in the center. Drill two 11/32" mounting holes in the flange so they'll match the holes that's in the adapter or 16hp engine block. The flange can be either round or oval in shape.
-
- Two (or four, with the 10hp, 12hp and 14hp engines) 5/16" (thread size) 1-1/4" long course thread Allen head bolts to fasten the adapter to the block. And use 1-1/4" long 5/16" diameter hardened studs w/nuts to fasten flange to adapter.
-
This is important! To
prevent the exhaust pipe from possibly breaking off at the weld point due
to normal engine vibration, fasten an "anti-vibration" brace (which is just
a piece of 1/8" thickness x 1" wide flat steel) from the upright portion
of the tubing (make sure it'll clear the hood) over to one of the cylinder
head bolts that's closest to the PTO end of the block. This brace is very
important because I think there's nothing more embarrassing and being
disqualified than having a welded-on header pipe break off at the weld and
land on the track while the tractor is pulling about halfway down the
track.
- MIG (wire feed) welder.
Here's how to fabricate your own exhaust header pipe:
- Depending on your model of tractor, have the tubing bent from the engine block (exhaust port) out enough so it'll clear the hood (for Cub Cadets, it's 7" from the port to the center of the upward pipe), and make the upright part of the pipe approximately 16" long.
- For the 10, 12 and 14hp engines - drill two 11/32" mounting holes that's spaced 1-13/16" apart in the adapter so they'll match the OEM threaded holes that's in the engine block. Then drill a 15/32" counterbore in the holes to sink the heads of the Allen head bolts so they'll clear the mounting flange. If there's two threaded bolt holes in the block (of the exhaust port), then you fasten the adapter (for the 10, 12 and 14hp blocks) or the flange (for the 16hp block) to the engine block with a couple of stainless steel Allen head screws. Be sure to clean the threads in the block with a 5/16-18 NC tap before installing the bolts. But if there's no holes present, then two must be drilled and tapped.
- For the 10, 12 and 14hp engines - drill and tap two other holes (5/16" coarse threads) in the adapter so they'll match the mounting holes on the flange.
-
Fasten the flange and/or adapter to the engine with the Allen head bolts.
If your engine block doesn't have the two holes, have it drilled and tapped
to accept the adapter for the exhaust pipe.
The two holes that's to be drilled and tapped
for the header pipe in the exhaust port of the engine block should be performed
on the table of a large milling machine by an experienced machinist. The
holes are to be drilled with a letter "F" or 17/16" drill bit, and about
1-1/4" deep. Then the threads cut perpendicular to the exhaust flange with
a 5/16-24 NC tapered tap. Use plenty of oil and go slow to prevent from breaking
the tap off in the block. Because if it breaks off, it'll be terribly hard
to remove.
- Install the adapter and/or flange on the engine, and with the engine (or tractor) on a level surface, install the tubing and align it with a level to make sure it's plumb (so it's exactly vertical) and tack weld it to the flange.
- Double check the vertical angle of the tubing from the front and side views and then permanently weld it in place.
- To fasten the anti-vibration brace to the header pipe, with an engine turning no more than 4,000 rpms, it's safe to install a stainless steel automotive radiator hose clamp. But if the engine is going to run at wide open throttle, it's best to use an automotive "U" shaped muffler clamp. These are available at any auto parts store.
- Before fastening the adaptor and/or flange to the engine block, apply a bead of RTV silicone sealer instead of gaskets. FYI - I always use silicone on my automotive intake manifolds and especially my automotive exhaust manifolds and header pipe flanges. I don't use gaskets when fastening the exhaust to the engine. Gaskets will flatten out and sometimes cause the manifold or flange bolts to loosen and/or warp the flanges, which will eventually cause an exhaust leak. Silicone will allow positive metal-to-metal contact, which keeps the bolts tight, and it fills in any imperfections between the two metals, eliminating an exhaust leak. Plus, extreme exhaust heat doesn't effect silicone whatsoever. So it's ideal for use when fastening the exhaust to an engine.
Advertisement:
| If you need a complete exhaust header pipe kit that's ready to bolt
on, please contact me, Brian Miller at A-1 Miller's
Small Engine (1501 West Old Plank Rd., Columbia, Missouri. 65203 | Phone:
1-573-875-4033). Please call any day between 12 noon and 8:00 p.m. Central
time, and please be patient because I stutter. Fax: 1-573-449-7347. You can
also contact me through Yahoo! Messenger:
|
 NOTE: None of
the header pipe kits below come with a clamp. To fasten the anti-vibration
brace to the pipe, with an engine turning no more than 4,000 rpms, it's safe
to use a stainless steel automotive radiator hose clamp. But if an engine
is going to run at wide open throttle, it's best to use a 1-1/2" automotive
"U" shaped muffler clamp. These are available at any auto parts store. By
the way - the anti-vibration brace is very important because I think there's
nothing more embarrassing and being disqualified than having a welded-on
header pipe break off at the weld while the tractor is pulling about halfway
down the track.
|
 Complete and
ready to bolt on, exhaust header pipe kit for 10hp, 12hp and 14hp Stock and
Stock-Altered Kohler engines with stock size valves and with or without a
working governor.
Kit includes a 1-3/16" i.d. x 1-5/16" o.d.. pipe. It measures approximately 7" from the block and approximately 19" tall, has a 90° semi-mandrel bend pipe, welded-on mounting flange, two Allen head stainless steel mounting bolts and an anti-vibration brace. Very shiny pipe, resists rust. Made of galvanized-coated steel. This is the only tubing I found that's the right size. Designed for use on Cub Cadets and most other makes & models of garden tractors with a 10, 12 or 14hp Kohler K-series or Magnum engines. This pipe has a welded-on flange that securely fastens to the engine block with two furnished 5/16" diameter coarse thread (5/16-18 NC) Allen head bolts. If your block don't have the two holes, then they will need to be drilled and threaded to accept the pipe. There is no other way to fasten this pipe to the block. Comes with no mounting gasket. Use silicone sealer instead. An adapter is NOT needed for these pipes because the flange is small enough to clear the governor lever. Shipping weight is 4 lbs.
|
 Complete and ready to
bolt on, exhaust header pipe kit for 10hp, 12hp and 14hp Stock-Altered and
30 c.i. Super-Stock Kohler engines with oversize valves and without a governor
lever.
Kit comes with a 1-3/8" i.d. x 1-1/2" o.d., from the center of the pipe, it measures approximately 7" from the block and approximately 19" tall, 90° bend pipe, welded-on mounting flange, two hex head stainless steel mounting bolts, two Allen head mounting bolts, block-to-flange adapter and an anti-vibration brace. High-quality 16 gauge aluminized steel automotive exhaust tubing, which looks nice and resists rust. The adapter securely fastens to the engine block with two furnished 5/16" diameter coarse thread (5/16-18 NC) Allen head bolts. If your block don't have the two holes, then they will need to be drilled and threaded to accept the pipe. There is no other way to fasten this pipe to the block. Comes with no mounting gasket. Use silicone sealer instead. Designed for use on Cub Cadets and most other makes & models of garden tractors with a 10, 12 or 14hp Kohler K-series or Magnum engines. Shipping weight is 5 lbs.
|
 Complete and ready to
bolt on, exhaust header pipe kit for 16hp Stock, Stock-Altered or Super-Stock
Kohler engines with stock 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. It measures approximately 7" from the block and approximately 19" tall, 90° bend pipe, welded-on mounting flange, two hex head stainless steel mounting bolts and an anti-vibration brace. High-quality 16 gauge aluminized steel automotive exhaust tubing, which looks nice and resists rust. This pipe has a welded-on flange that securely fastens to the engine block with two furnished 5/16" diameter coarse thread (5/16-18 NC) bolts. If your block don't have the two holes, then they will need to be drilled and threaded to accept the pipe. There is no other way to fasten this pipe to the block. Comes with no mounting gasket. Use silicone sealer instead. Designed for use on Cub Cadets and most other makes & models of garden tractors with a 16hp Kohler K-series or Magnum engine. Shipping weight is 4 lbs.
|
| NOTE: I can also make header pipes for other makes and models of engines. I'll need to know the outside diameter of the pipe, the overall length, how far it will need to come out from the engine to clear the hood, how many bends it will need, and the dimensions of the mounting flange. You can order larger diameter header pipes from either Lakota Racing, Midwest Super Cub or Nichols Performance. |
 Steel exhaust pipe mounting
flange-to-engine block for 10, 12 and 14hp single cylinder, and KT17, KT19,
M18 and M20 twin cylinder Kohler and Magnum flathead engines. Approximately
3/16" thickness, (2) 21/64" diameter mounting holes spaced 1-3/4" apart,
1-5/16" center hole. No adapter required. $8.00 each, plus shipping.
Steel exhaust pipe mounting flange to engine block for 16hp Kohler engines.1/4" thick, 2 bolt holes, 1-1/2" center hole. To be welded onto a 1-1/2" o.d. exhaust pipe. Fits perfectly on the 16hp Kohler K-series and Magnum flathead engines and adapter below. $8.00 each, plus shipping. |
 Steel exhaust port to header
flange adapter for 10, 12 and 14hp Kohler and Magnum flathead engines.. Used
to adapt the Kohler engine block to the flange (above) on the header pipe
because the holes in the exhaust port aren't spaced out enough to accept
the flange alone. Has a 1-3/16" center hole. Made of steel. $20.00
each, plus shipping.
Please contact me if you're interested in any of the above parts or services. |
Linked pages to my parts & services:
Please click HERE, e-mail me at pullingtractor@aol.com or call me at 1-573-875-4033 if you need machine work performed, repairs made, various parts, if your business would like to help sponsor my web sites or if you'd like to make a donation towards my web sites. Please call between 12 noon and 8:00 p.m. Central time, and please be patient because I stutter.
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