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Kohler's 16hp engine cylinder headInformation About Cylinder Heads For Kohler Engines

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Identification of Kohler K-series and Magnum Single Cylinder Engine Cylinder Heads -

The cylinder head used on Kohler engine model models K141 (6¼hp), K160 (6.6hp), K161 (7hp) and K181/M8 (8hp) was introduced in 1952, and are all identical. There is no difference. These heads shouldn't be milled because the valves are already close to the head when the valves are at full lift. All that can be done is resurface it on a wide flat sanding belt or large diameter disc sander to remove warpage and restore flatness, and to prevent a blown or leaking head gasket. OEM Kohler part # 41 755 25-S.

Kohler made five different cylinder heads for the 10hp, 12hp and 14hp K-series and Magnum engines through the years -

The First Generation Head -

This cylinder head was manufactured by Kohler from the early 1960s until 1971 and was available only on engine model K241 (10hp) before engine serial number 3184999. It has a heart-shaped and wedge-contoured combustion chamber and is now known as the high compression, "LP head." The spark plug is centered in the combustion chamber. This particular head was originally made for and came on the very early K241 (10hp) engines. It'll also work on the Magnum engine model M10 (10hp), K301/M12 (12hp) engines and the early K321/M14 (14hp) engines with a 1-1/8" exhaust valve. But being the later 14hp engines have a larger exhaust valve (1-3/8"), the exhaust area in the head would need to be machined out for use with the bigger exhaust valve. And because of its high compression ratios, if this head is used on a 12 or 14hp engine, Premium, race gas, E-85 or methanol fuels must be used, or the engine will overheat and wear out too soon. The compression ratio is 7:1 when used on a 10hp and 8.6:1 when used on a 12hp. If this head was used on a 14hp, it would yield a 9:1 compression ratio. And LP heads did not come on nor will they fit the 16hp (K341) engines. This head requires 2-1/2" length bolts. And due to early technology and design of the combustion chamber, the majority of the expanding gases or combustion pressure is placed over the valves instead of the piston, resulting in lower engine performance. The number embossed on this head is 235461. Cub Cadet part # is IH-385303-R1. It is no longer available from Kohler or new from any other source.

NOTE: This particular head was originally designed many years ago ONLY for the 10hp (K-241) engine because these engines have low compression due to their small bore and short stroke. The only reason anyone would put one of these heads on a bigger engine today is to attempt to get more power out of it. Also, people found that the LP head worked better than a newer low compression head on an engine burning liquefied petroleum (propane) gas. LP gas is a high octane fuel (about 110-115 octane). Therefore, it burns more thoroughly and produces more power in a high compression engine. That's why these heads are known today as the "LP head." Also, the LP head, when used on any size engine including the 10hp, have been known to cause detonation (pinging) nowadays even with 93 octane Premium gas. That's why Kohler stopped making them. They replaced them with the "dished" head. Ê However, high octane race gas, E-85 or methanol fuels can be safely used with the LP head.

If you want to use an LP head on your engine, the genuine OEM Kohler LP head is no longer available from Kohler or any other source. They haven't been made since the early 1960s. They were discontinued when the 12hp engine came into production, because this engine require a lower compression head. So if you need an LP head, remember, they came only on the very early 10hp engines equipped with the starter/generator and no indention on the side of the block for the upper mount gear starter. But if you can't find an LP head at all or for a reasonable price, what you could do is cast an aluminum head just like the LP head. An LP head can be CNC-machined from billet aluminum, but if you prefer a head that's close to the genuine product, first, you'll need a good LP head to use as a mold or pattern. For more information on this subject and a how-to video, click here: Melting Cans With The Mini Metal Foundry - YouTube.

The Second Generation Head -

The second type of head manufactured by Kohler has a heart-shaped and a depression area in the combustion chamber. It has improved technology over the earlier LP head. Kohler engine engineers made the depression area for a special reason and it helps engines to produce more torque and horsepower than the LP head at any RPM. This head was installed on Kohler's 10hp and 12hp engines, before the 14hp engine went into production. It's a good head. It flows good and with increased compression. The "hump" directs the incoming air/fuel toward the piston at higher RPM.

Unlike the sought-after, but misunderstood LP head, the depression area places the majority of the expanding gases or combustion pressure over the piston instead over of the valves, which produces more engine power and torque. The spark plug is centered in the combustion chamber. It was lowered in compression and was made for both the 10hp and 12hp engines, but would not work on the 14hp engine because of its' larger exhaust valve (it was manufactured before the 14hp engine appeared) unless reduce the size of the exhaust valve on a 14hp to a 1.125" (same as a 10 & 12hp) This can be accomplished by installing a valve seat insert in the block for the smaller valve. By the way - this type of head is not officially a "high compression head" because it has a depression in the combustion chamber. It is however, 'slightly higher' in compression than the newer style heads, but it's not a "high compression" or even an "LP head," but the next best to it. The compression ratio is 5.4:1 when used on a 10hp and 6.6:1 when used on a 12hp. If this head was used on a14hp (the exhaust circumference area would need to be machined larger), it would yield a 7:1 compression ratio. By the way - Kohler no longer makes this type of head either.

These early heads require 2-1/2" length bolts (OEM Kohler part # 236546-S; no longer available from Kohler; number embossed on head is 235461, but not an LP head), and the later ones require 1-1/2" length bolts (OEM Kohler part # 236675-S). Also, the reason Kohler redesigned the head with the low bosses for shorter head bolts is so more air flow can past over the head bolts to better efficiently cool the other parts of the head.

The Third Generation Head -

The third head manufactured by Kohler has a low compression (depressed) D-shaped combustion chamber. And unlike the sought-after, but misunderstood LP head, the depression area places the majority of the expanding gases or combustion pressure over the piston instead over of the valves, which produces more engine power and torque. The spark plug is centered in the combustion chamber. It'll work on the 10hp, 12hp and 14hp engines because the exhaust valve area was made bigger. (It was manufactured when the 14hp engine first appeared.) The compression ratio is 5:1 when used on a 10hp, 6.1:1 when used on a 12hp, and 6.6:1 when used on a 14hp. This head requires 1-1/2" length bolts. The reason Kohler lowered the bolt hole bosses is to allow more air to flow over the fins for better cooling of the engine. By the way - Kohler no longer makes this type of head either. If you want to use one of these, look for a good used one. They came on the later model 10hp, 12hp and 14hp engines. OEM Kohler part # 237827-S.

The Fourth Generation and Newest Style Head -

The newest style head manufactured by Kohler is much like the previous one, but has the spark plug located directly over the exhaust valve. There are two reasons why Kohler did this:

Again, unlike the sought-after, but misunderstood LP head, the depression area places the majority of the expanding gases or combustion pressure over the piston instead over of the valves, which produces more engine power and torque. The compression ratios and mounting bolt lengths are the same as the previous head. By the way - these type of heads are available from Kohler and are the newest ones made. They come on Magnum engines, too.

By the way - the Chevrolet V8 performance racing cylinder heads have the spark plug tip moved toward the exhaust valve for improved performance. It works. The plugs are angled so the tip is closer to the exhaust valve, and so the porcelain part will clear the exhaust header pipes. There's no reason to angle the spark plug in a Kohler head.

NOTE: The fourth generation head will interchange on the 10hp, 12hp and 14hp engines. It doesn't matter about the spark plug location, except for pulling purposes. For pulling, it's best to have the spark plug directly over the exhaust valve. The only exception is the very early 10hp "LP" head. It has a smaller combustion chamber which will allow the engine to have a higher compression ratio, and shouldn't be used on the 12 and 14hp engines for general yard work. It should be used for pulling purposes only using high octane gas, E-85 or methanol fuel. The reason for this is because the compression will be so high, the engine will run too hot for low octane gas, and severe damage to the engine may result.

The K341/M16 (16hp) Cylinder Head -

The 16hp (K341) head that's manufactured by Kohler is in a class by itself. It has the depression and D-shaped combustion chamber. They have the spark plug located directly over the exhaust valve. The compression ratio is 7.4:1. It requires 1-1/2" length bolts. And there are no "LP" type 16hp cylinder heads. And ALL K341/M16 16hp Kohler cylinder heads have the spark plug located over the exhaust valve. No exceptions. OEM Kohler part # 45 015 09-S.

Compression ratios for factory stock Kohler engine models are as follows:
K90 (3.6hp), K91 (4hp) ? K141 (6¼hp) - 5.93:1 K160/K161 (7hp) - 6.2:1
K181/M8 (8hp) - 6.8:1 K241/M10 (10hp) - 5:1, 5.4:1 or 7.1:1 (depending which head is used) K301/M12 (12hp) - 6.1:1, 6.6:1 or 8.6:1 (depending which head is used)
K321/M14 (14hp) - 6.6:1, 7:1 or 9:1 (depending which head is used) K341/M16 (16hp) - 7.4:1 K361 (18hp OHV) - 9.2:1

Kohler Cylinder Head Identification and Cub Cadet Applications:

A good head for a Stock pulling tractor with the engine running around 4,000 RPM would be the one with the spark plug located in the center of the combustion chamber. And the best head to use for a high RPM pulling tractor would be the one with the spark plug located over the exhaust valve.

Did you know that installing two spark plugs per cylinder doesn't help to increase the power output of an engine whatsoever? Simply because one plug will be running hot (exhaust side) and the other will be cool (intake side). Engine power is generated from the heat source, because heat is how an engine produces power. When the spark plug in the cylinder head is located over (flathead) or close to (OHV) the exhaust valve, this maintains the majority of the heat in the combustion chamber in one area. When heat is maintained in one particular area in any given combustion chamber, the increase in power will be much greater, especially at high RPM. Burning fuel within a combustion chamber will "find" or locate the main heat source. The fuel will burn more thoroughly, allowing the engine to produce more power at any RPM. If the plug is located in the center of the combustion chamber, the incoming fuel could splash against the plug's tip and cause the engine to misfire or run erratic at high speed, especially when burning methanol fuel. And the plug could easily become fouled when burning gas, especially when the engine is cold. So it's best to install just one spark plug positioned over the exhaust valve with the plug gap set at .060". Because a .060" gap will simulate having two spark plugs. Use of a high-performance coil will help produce a stronger spark, too. Indexing the spark plug will also help to increase power and torque. This is when the open gap faces the center of the piston. It helps in a more thorough combustion of the fuel so the engine will produce more power at high RPM. Indexing washers is used to index a spark plug. They're a copper washer of certain thicknesses that's placed on the threads of the plug. Indexing of the spark plug helps to increase the power on a high-performance engine that operates at high RPM. It doesn't help much on a stock engine or at low RPM.

Grind away any sharp edges (after milling head, milling out combustion chamber and/or factory casting flash) within the combustion chamber, and polish the entire combustion chamber, including around the valves and top of the piston, to a high luster (smooth as glass, if possible) to help increase power and torque, especially at higher RPM or at wide open throttle. Removing sharp edges prevents hot spots, which can cause detonation and/or pre-ignite the incoming fuel, and polishing reflects heat and prevents the majority of it from being absorbed into the metals. Go here for more information on this subject.

If you're pulling in class where the rules read that you must use a stock OEM cylinder head, stock valve lift and stock diameter valves, and you want to get a little more power out of your engine, what can be done is "shave" or mill the head. This is when approximately .050" of metal is removed from the prominent/raised gasket mating surface ridge. To guarantee that the head is absolutely parallel, this must be performed on a milling machine with a flycutter and not with a sanding belt or disc sander. Use a wide flat sanding belt or large diameter disc sander only to resurface a warped cylinder head to restore flatness. If the sanding material on a wide sanding belt or large diameter disc sander is worn uneven (from multiple sandings), the head won't resurface perfectly flat and/or may have skip marks.

Milling of the head (remove the raised ridge that mates with the head gasket) will increase the compression ratio about 3/4 of a point. And depending on engine size, this will add about 1-3 more horsepower. The engine will have a "snappier" response when the throttle is opened suddenly. Be sure to check the valve clearance before milling a head! If a lot of metal is removed from the head, then milling of the valve cavity to clear the head may need to be done. In most cases with a stock-lift cam, there should be adequate clearance once the head is milled. Always check the clearance with the valves at full lift before milling a head! To learn how to do this, scroll down or click here. To learn what else can be done to a stock engine to increase it's power output, click here.

Milling of a cylinder head is performed with a flycutter and the head clamped in a milling machine vise that's fastened to the table of a milling machine. First, securely clamp the head with the fins upward in the vise and use a couple of parallels to ensure that the head is exactly at a 90º angle with the spindle. Then remove just enough metal from the fins with the flycutter so they are all even. Next, flip the head over in the vise and mill (or cut) the gasket mating area until the desired amount of metal is removed (so many thousands of an inch) or until the flycutter starts to touch the flat area above the piston.

Reusing Metal-Shielded Head Gaskets -

A used metal-shielded head gasket can be reused if it is in good condition and not bent, distorted or burned-out. To reuse it, clean it thoroughly with a spinning wire wheel, coat it evenly with ordinary aluminum spray paint, and then reinstall the gasket and torque the head bolts to specs. Normal operating engine combustion heat will melt the aluminum paint, creating an absolutely perfect seal. And if a new, metal-shielded head gasket has light surface rust from sitting in storage, the rust can be removed with a spinning wire wheel, and then the gasket can be coated with aluminum spray paint. It'll still be a usable gasket, only with a much better appearance (and sealing quality). This will not work with heavily-rusted head gaskets. And did you know that aluminum paint was first applied on used head gaskets to reassemble engines that was in the American World War 2 fighter planes? Aluminum paint was used because at the time there was a shortage of new head gaskets. This is part of the reason why most Americans don't speak German or Japanese today.

If an engine has a leaking head gasket, then this means either the head bolts are loose or the cylinder head is warped and needs to be resurfaced on a wide flat sanding belt or large diameter disc sander to remove warpage and restore flatness. And if the head is perfectly flat and if the head bolts or studs w/nuts are torqued to specs, most head gaskets alone will seal with no problems. But if you want a guarantee that the gasket will seal well, apply a thin layer of either VersaChem - Mega Copper Silicone, Permatex® Ultra Copper® Maximum Temperature RTV Silicone Gasket Maker or Copper SPRAY-A-GASKET Hi Temp Adhesive Sealant on each side of the head gasket or on the cylinder head and engine block, then torque the bolts or studs w/nuts to factory specs. These products have fine-ground soft copper particles for heat transfer and the silicone is to seal in the combustion. Engine heat has very little effect on silicone rubber. These products work equally. I don't think one works better than the other.

For competition pulling only: If the deck (top) of the engine block and cylinder head gasket surface are perfectly flat, and if the valves have adequate head clearance at full lift, and if the piston doesn't come flush with the top of the block, or if the head is milled for a pop-out piston, then a head gasket isn't really necessary. Just use the copper silicone as described above È. When using copper/silicone only as a head to block sealant, it'll be like using a dried "liquid" copper head gasket. The absence of a head gasket will prevent the head from warping when the head bolts or nuts with studs are torqued to specs. The head and block will have positive metal to metal contact with the silicone filling in any imperfections between the two metals. The copper particles will transfer the heat. But if the piston pops out of the cylinder, the clearance between the piston and head will need to have a safety margin of minimum .030" due to rod stretch and crankshaft flex at very high RPM. And yes, when precision-balanced, even a cast iron crankshaft will flex a few thousands of an inch at high RPM without breaking. The clearances over each valve when at full lift will need to be checked, too.

On some [dirty] blocks, to prevent a blown head gasket, besides resurfacing the head(s), due to dirt/debris in the threads for the head bolts, the threads may need to be cleaned out with the appropriate size tap (5/16-18 NC for the Kohler K141, K161, and K181/M8 engines; and 3/8-NC for the Kohler K241/M10, K301/M12, K321/M14, K341/M16 and K361 engines) to get the head bolts to fully compress the head and gasket when torqued to specs. Be sure the threads on the bolts are clean, too. And to obtain the proper torque, apply clean motor oil on the threads before installing and torquing the bolts to specs. This should be done with any engine, lawn & garden, farm, heavy equipment or automotive.

And OEM Kohler head bolts don't need to be retorqued after the engine gets hot. Also, as long as there's plenty of metal on the hex head (due to being rusted away), they can be reused many times. The OEM Kohler head bolts are actually harder than hardware store grade 8 bolts and the threads don't stretch on them whatsoever. Personally, I always try to reuse Kohler head bolts on my engine builds whenever possible.

To repair broken-off head bolt(s)...

  1. Try applying GUNK Liquid Wrench to the broken stud(s), allow the Liquid Wrench to soak in after a few minutes, then use Vise-Grips locking pliers to very gently twist the stud back and forth.
  2. If the first step doesn't work, heat the area around the stud with an oxy-acetylene welding torch and twist the stud with the Vise-Grips again.
  3. If the above still don't work, as the last result, the broken stud(s) will need to be ground flush with the surface on the block, carefully drilled out perpendicular with the block, and the threads retapped. (The studs are obviously made of mild steel. That's why it/they broke off in the first place.)
  4. Resurface the cylinder head on a wide flat sanding belt or large diameter disc sander to remove warpage and restore flatness, and install new grade 8 bolts with anti-seize compound on the threads.

And for general yard work, to lessen the chance of a blown or leaking head gasket, seal the head gasket with either VersaChem - Mega Copper Silicone, Permatex® Ultra Copper® Maximum Temperature RTV Silicone Gasket Maker or Copper SPRAY-A-GASKET Hi Temp Adhesive Sealant. Apply it on both sides of the head gasket or cylinder head and engine block. And always torque the head bolts in the correct sequence to proper specs.

The causes of "burn-out" on an OEM aluminum cylinder head on virtually any 4-cycle small gas engine are:

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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 (shop) | 1-573-881-7229 (cell). 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.) A-1 Miller's shop is open to the public from 9am to 5pm, including weekends (except Holidays). Please call before coming so I'll be here waiting for your arrival. Fax: 1-573-449-7347. E-mail: pullingtractor@aol.com. Directions to our shop | 1501 West Old Plank Road, Columbia, MO - Google Maps or Map of 1501 West Old Plank Road, Columbia, MO by MapQuest. NOTE: To place an order, please call either number above or send an email with a list and description of the parts or services you need. Because as of right now, my websites are not set up to accept orders online.
Cylinder Head Work -
  • Resurface air-cooled small engine cylinder head on wide flat sanding belt or large diameter disc sander to remove warpage and restore flatness, and deburr sharp edge around combustion chamber. $10.00 labor, plus return shipping & handling.
  • Mill cylinder head approximately .050". Remove prominent/raised gasket mating surface from head to increase compression ratio for the 10-16hp flathead, K-series or Magnum single cylinder engines only. $25.00 labor each, plus return shipping & handling. NOTE: Seal the head gasket with VersaChem - Mega Copper Silicone, Permatex® Ultra Copper® Maximum Temperature RTV Silicone Gasket Maker or Copper SPRAY-A-GASKET Hi Temp Adhesive Sealant on each side of the head gasket or cylinder head and engine block to prevent a blown or leaking head gasket. Because engine heat has very little effect on silicone rubber.
  • Mill out exhaust valve cavity in LP and 2nd generation cylinder head to clear the larger 1-3/8" exhaust valve. $25.00 labor each, plus return shipping & handling.
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. And I don't sell the aftermarket bronze valve seats that are installed in the K361 heads because they are machined from scratch. Due to the molded-in tongue and groove installation of the OEM valve seats by Kohler, the outside diameter of the bronze seats can vary a lot according to how much trouble it is to remove the OEM valve seats from the head. Contact Elson Nichols at 573-449-0983 for more details of the bronze valve seats. Click here for cylinder head bolt torque specs.
  • 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 on wide flat sanding belt or large diameter disc sander to remove warpage and restore flatness. $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.

Gasket kit to reinstall the K361 cylinder head on the engine. Includes: head gasket (part # 45 052 02-S; $24.00), rocker arm housing gasket (part # 45 041 14-S; $14.00), rocker arm housing cover gasket (part # 45 041 09-S; $5.75), two pushrod tube O-rings (part # 45 153 01-S; $2.00/two), and intake tube mounting gasket (part # 271030-S; $1.00). All parts total: $46.75, plus 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.)

  • High quality aftermarket. $42.00 each, plus shipping & handling.
  • OEM Kohler part # 45 755 06-S. $110.00 each, plus shipping & handling.

New Intake Valve for Kohler engine model model K361 (18hp OHV). Dimensions: head diameter: 1.437"; overall length: 4.175"; stem diameter: .3095"; face angle: 45º.

  • OEM Kohler part # 45 017 01-S. $126.10 each, plus shipping & handling.

NOTE: A new exhaust valve for Kohler engine model model K361 (18hp OHV) is part # 45 016 02-S, and 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 new old stock (NOS). The dimensions for machining an exhaust valve from a larger one are: head diameter: 1.437"; overall length: 4.158"; stem diameter: .309"; face angle: 45º. (The OEM [US] 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.)

Valve Guides for Kohler engine model model K361 (18hp OHV) cylinder head.

  • Intake Valve Guide. OEM Kohler part # 45 316 02-S. $12.40 each, plus shipping & handling.
  • Exhaust Valve Guide and Seal Kit. OEM Kohler part # 45 755 11-S. $56.95 each kit, plus shipping & handling.
Cylinder head gasket for Kohler flathead engine models K90 (3.6hp), K91 (4hp). Approximately .050" compressed thickness. Doesn't need to be retorqued once hot. Included in complete engine rebuild gasket set. Click here for cylinder head bolt torque specs.
  • Aftermarket. $8.00 each, plus shipping & handling.
  • OEM Kohler part # 220124-S. $9.10 each, plus shipping & handling.
Cylinder head gasket for Kohler K-series and Magnum flathead engine models K141 (6¼hp), K160 (6.6hp), K161 (7hp) and K181/M8 (8hp). Approximately .050" compressed thickness. Doesn't need to be retorqued once hot. Included in complete engine rebuild gasket set. Click here for cylinder head bolt torque specs.
  • Aftermarket. $7.00 each, plus shipping & handling.
  • OEM Kohler part # 41 041 10-S. $9.10 each, plus shipping & handling.
Cylinder head gasket for Kohler K-series and Magnum flathead engine models K241/M10 (10hp), K301/M12 (12hp) and K321/M14 (14hp). Approximately .050" compressed thickness. Doesn't need to be retorqued once hot. Included in complete engine rebuild gasket set. Click here for cylinder head bolt torque specs.
  • Aftermarket. $6.25 each, plus shipping & handling.
  • OEM Kohler part # 47 041 15-S. $14.75 each, plus shipping & handling.
Cylinder head gasket for Kohler K-series and Magnum flathead engine models K341/M16 (16hp). Approximately .050" compressed thickness. Doesn't need to be retorqued once hot. Included in complete engine rebuild gasket set. Click here for cylinder head bolt torque specs.
  • Aftermarket. $11.50 each, plus shipping & handling.
  • OEM Kohler part # 45 041 17-S. $14.80 each, plus shipping & handling.
Cylinder head gasket for Kohler K-series engine model K361 (18hp OHV). Approximately .050" compressed thickness. Doesn't need to be retorqued once hot. Included in complete engine rebuild gasket set. This part alone is discontinued from Kohler. OEM Kohler part # 45 052 02-S. Not available in aftermarket. L Click here for cylinder head bolt torque specs.
  • NOS (New Old Stock). $24.00 each, plus shipping & handling.
Cylinder Head Gasket for Tecumseh engine models VH80, HH80, VH100 and HH100. Approximately .050" compressed thickness. Doesn't need to be retorqued once hot. OEM Tecumseh part # 32000B.
  • $7.00 each, plus shipping & handling.
Cylinder head gasket for Kohler KT-series and Magnum opposed (flathead) twin cylinder engine models MV16, KT17, KT17II, KT19, KT19II, M18, MV18, M20 and MV20. Approximately .050" compressed thickness. Doesn't need to be retorqued once hot. Included in complete engine rebuild gasket set. Click here for cylinder head bolt torque specs.
  • Aftermarket. $10.00 each, plus shipping & handling.
  • OEM Kohler part # 52 041 20-S. $19.00 each, plus shipping & handling.
Cylinder head gasket for Kohler opposed (flathead) twin cylinder engine models K482, K532 and K582. Approximately .050" compressed thickness. Doesn't need to be retorqued once hot. Included in complete engine rebuild gasket set below Ê.
  • Aftermarket. $7.00 each, plus shipping & handling.
  • OEM Kohler part # 48 041 13-S. $8.40 each, plus shipping & handling.
Stripped Spark Threads Repair Service - No need to purchase another cylinder head! The repair services below also includes resurfacing of air-cooled small engine cylinder head to remove warpage and restore flatness.
  • Install Heli-Coil thread repair insert for normal stripped spark plug hole. $10.00 each for parts and labor, plus return shipping & handling.
  • Install 1/2 NPT steel pipe plug for oversized stripped spark plug hole up to 5/8" diameter, and machine pipe plug for installation of new spark plug threads. $40.00 each for parts and labor, plus return shipping & handling.
  • Weld up hole larger than 5/8" diameter, and machine aluminum welding for installation of new spark plug threads. $60.00 each for parts and labor, plus return shipping & handling.
Refurbished OEM Cylinder Heads. The heads below have been cleaned and resurfaced on a wide sanding belt or large diameter disc sander to remove warpage and restore flatness, with good fins and spark plug threads. NOTE: The length of a bolt do not include the head itself. All bolts are measured from under the head to the end of the threads.
Cylinder head for Kohler K-series engine models K90 (3.6hp) and K91 (4hp). Discontinued from Kohler. Click here for cylinder head bolt torque specs. OEM Kohler part # 220541-S.
  • Used and reconditioned. $50.00 each, plus shipping & handling. (When available.)
Cylinder head for Kohler engine model models K141 (6¼hp), K160 (6.6hp), K161 (7hp) and K181/M8 (8hp). Click here for cylinder head bolt torque specs.
  • Used and reconditioned. Cylinder head only. Discontinued from Kohler. OEM Kohler part # 41 015 09-S. $50.00 each, plus shipping & handling. (When available.)
  • New cylinder head kit. Includes: cylinder head; 5/16" grade 5 hex nut; Sems screw 1/4-20 x 5/8 (X-132-5-S); Stud (52 072 15-S). OEM Kohler part # 41 755 25-S. $151.10 per kit, plus shipping & handling.
1st generation high compression "LP" cylinder head for Kohler engine model models K241/M10 (10hp), K301/M12 (12hp) and early K321 (14hp) with small diameter 1-1/8" exhaust valve. NOTE: To use this head on a K321/M14 (14hp) engine, if the block has the bigger 1-3/8" exhaust valve, the exhaust valve area in the head will need to machined larger. But if it has the small valve, the head won't need to be machined. Numbers 235461 embossed on head. Click here for cylinder head bolt torque specs. Discontinued from Kohler many years ago. OEM Kohler part # 235475-S. Cub Cadet part # IH-385303-R1.
  • Used and reconditioned. Requires 2-1/2" length bolts. $160.00 each, plus shipping & handling. (When available.)
2nd generation cylinder head for Kohler engine model models K241/M10 (10hp), K301/M12 (12hp) and early K321 (14hp) with the small diameter 1-1/8" exhaust valve. These have a centered spark plug hole and a heart-shaped combustion chamber. NOTE: To use this head on a K321/M14 (14hp) engine, if the block has the bigger 1-3/8" exhaust valve, the exhaust valve area in the head will need to machined larger. But if it has the small valve, the head won't need to be machined. Click here for cylinder head bolt torque specs.
  • Used and reconditioned. Numbers 235461 embossed on head, but this is NOT the LP head. Requires 1-1/2" length bolts. OEM Kohler part # 236546-S. No longer available from Kohler. $50.00 each, plus shipping & handling. (When available.)
  • Used and reconditioned. Numbers 235461 embossed on head, but this is NOT the LP head. Requires 2-1/2" length bolts. OEM Kohler part # 236675-S. $70.00 each, plus shipping & handling. (When available.)
  • New. Requires 1-1/2" length bolts. OEM Kohler part # 236675-S. $196.30 each, plus shipping & handling.
3rd generation cylinder head for Kohler engine model models K241/M10 (10hp), K301/M12 (12hp) and K321/M14 (14hp). These have a centered spark plug hole and a bigger, D-shaped combustion chamber to clear the large diameter 1-3/8" K321/M14 14hp exhaust valve. Click here for cylinder head bolt torque specs.
  • Used and reconditioned. Requires 1-1/2" length bolts. $50.00 each, plus shipping & handling. (When available.)
  • Used and reconditioned. Requires 2-1/2" length bolts (early 2-1/2" heads have 235820 embossed on head). $70.00 each, plus shipping & handling. (When available.)
  • New. OEM Kohler part # 237827-S. Requires 1-1/2" length bolts. $188.20 each, plus shipping & handling.
  • New. OEM Kohler part # 237829-S. Requires 2-1/2" length bolts. $193.00 each, plus shipping & handling.
4th generation cylinder head for Kohler engine model models K241/M10 (10hp), K301/M12 (12hp) and all K321/M14 (14hp). This is the newest style head. This head has an offset spark plug hole located over the exhaust valve and a bigger, D-shaped combustion chamber to clear the large diameter 1-3/8" K321/M14 14hp exhaust valve. These particular heads lessens the chance of plug fouling from cold starting and helps produce more power at higher RPM by retaining majority of combustion heat in one area. Click here for cylinder head bolt torque specs.
  • Used and reconditioned. Requires 1-1/2" length bolts. $75.00 each, plus shipping & handling. (When available.)
  • New. OEM Kohler part # 47 015 05-S (Listed for Magnum M10). Requires 1-1/2" long bolts. $120.20 each, plus shipping & handling.
Cylinder head for Kohler engine model models K341/M16 (16hp). Each requires 1-1/2" length bolts. NOTE: All K341/M16 16hp Kohler cylinder heads have the spark plug located over the exhaust valve. No exceptions. Click here for cylinder head bolt torque specs. OEM Kohler part # 45 015 09-S.
  • Used and reconditioned. $120.00 each, plus shipping & handling. (When available.)
  • New. $203.15 each, plus shipping & handling.
Stock Cylinder Heads for Kohler Magnum opposed (flathead) twin cylinder engine model MV16. Same head is made for either side of engine. Click here for cylinder head bolt torque specs. OEM Kohler part # 52 015 10-S.
  • Used and reconditioned. $35.00 each, plus shipping & handling. (When available.)
  • New. $122.35 each, plus shipping & handling.

Stock Cylinder Heads for Kohler KT-series and Magnum opposed (flathead) twin cylinder engine models KT17, KT17II, KT19, KT19II, M18, MV18, M20, MV20. Same head is made for either side of engine. See torque specs and sequence here. OEM Kohler part # 52 015 08-S.

  • Used and reconditioned. $50.00 each, plus shipping & handling. (When available.)
  • New. $156.40 each, plus shipping & handling.
Cylinder Head Bolts and Flat Washers for Kohler engine model models K141, K160/K161, K181 and M8. Replace bolts with rusted heads to prevent socket from slipping. NOTES: Clean and oil threads in block with a 5/16-18 UNC plug hand tap so bolts will torque correctly. Torque each bolt to 240 in. lbs. or 20 ft. lbs. Click here for cylinder head bolt torque specs.
  • Set of 7 each, 5/16" diameter x 1-1/2" thread length grade 8 bolts and hardened washers.
    • High quality aftermarket. $10.50 per set, plus shipping & handling.
    • OEM Kohler part #'s 41 086 02-S (bolt), 220534-S (washer). $49.35 per set, plus shipping & handling.

Cylinder Head Bolts and Flat Washers for Kohler engine model models K241/M10, K301/M12, K321/M14 and K341/M16. Replace bolts with rusted heads to prevent socket from slipping. NOTES: Clean and oil threads in block with a 3/8-16 UNC plug hand tap so bolts will torque correctly. Torque each bolt to 360 in. lbs. or 30 ft. lbs. The length of any bolt do not include the head itself. All bolts are measured from under the head to end of the threads.Bolt length is determined by type of cylinder head used. A head with short bolt holes requires 1-1/2" thread length bolts, and a head with tall bolt holes requires 2-1/2" thread length bolts. Click here for cylinder head bolt torque specs.

  • Set of 9 each, 3/8" diameter x 1-1/2" thread length grade 8 bolts and hardened washers for Kohler engine model models K241/M10, K301/M12 and K321/M14.
    • High quality aftermarket. $13.50 per set, plus shipping & handling.
    • OEM Kohler part #'s 25 086 115-S (bolt, 270889-S (washer). $64.75 per set, plus shipping & handling.
  • Set of 9 each, 3/8" diameter x 2-1/2" thread length grade 8 bolts and hardened washers for Kohler engine model models K241/M10, K301/M12 and K321/M14.
    • High quality aftermarket. $13.50 per set, plus shipping & handling.
    • OEM Kohler part #'s 235175-S (bolt), 270889-S (washer). $98.00 per set, plus shipping & handling.
  • Set of 10 each, 3/8" diameter x 1-1/2" thread length grade 8 bolts and hardened washers for Kohler engine model models K341/M16.
    • High quality aftermarket. $15.00 per set, plus shipping & handling.
    • OEM Kohler part #'s 25 086 115-S (bolt), 270889-S (washer). $69.70 per set, plus shipping & handling.
  • Set of 6 each, 3/8" diameter x 1-1/2" thread length grade 8 bolts and hardened washers for Kohler engine model model K361.
    • High quality aftermarket. $9.00 per set, plus shipping & handling.
    • OEM Kohler part #'s 270721-S (bolt), 270889-S (washer). $65.35 per set, plus shipping & handling.

Single Cylinder Head Stud Kits for Kohler engine model models K241/M10, K301/M12, K321/M14, K341/M16 and K361 with an OEM or Billet Head. Each kit includes 3/8" diameter x 2" or 2-3/4" length high quality heat-treated studs, grade 8 nuts and hardened flat washers. I can also make the head studs any length you want. The ones that's listed here are the most common lengths. When installed correctly and torqued to specs, head studs provide even torque pressure for better head gasket sealing. Plus, with a thinner cylinder wall with a huge, oversized piston, they help maintain cylinder wall stability and straightness for better ring seal to lessen the loss of compression. Thoroughly tested for several years of continuous use under pulling conditions, for Kohler engine models, hardened and heat-treated coarse thread studs, along with grade 8 nuts and washers, works just fine, with no problems. The nuts maintain their torque as long as they're tightened to the correct torque specs. And make sure at least 3/4" of threads are in the block so the cylinder wall will not distort and threads in block will not strip out when the nuts are torqued to specs. Click here for cylinder head bolt torque specs. (Cast iron is weaker than hardened steel.) Also, the flat washers goes under the nuts to distribute even pressure across head. IMPORTANT: As with any stud, apply medium strength liquid threadlocker (Blue Loctite, Permatex or equivalent) on threads that goes in block to prevent stud from loosening. Apply motor oil on stud threads so nut will torque correctly. Torque each nut to 360 in. lbs. or 30 ft. lbs. in correct sequence. Also, stud length is determined by type of cylinder head. The OEM head with short bolt holes require 2" length studs, the head with tall bolt holes require 2-3/4" length studs. Please indicate length of studs when placing order. An innovative concept by Brian Miller. Accept no copycat parts!

  • For Kohler engine model models K241/M10, K301/M12 and K321/M14. 2" or 2-3/4" length (please specify length). Set of 9 studs, nuts and washers. $20.00 per set, plus shipping & handling.
  • For Kohler engine model models K341/M16. 2" length. Set of 10 studs, nuts and washers. $22.00 per set, plus shipping & handling.
  • For Kohler engine model model K361. 2" length. Set of 6 studs, nuts and washers. $13.00 per set, plus shipping & handling.

Kohler K-Series and Magnum Single Cylinder Engine Torque Values and Sequences for Spark Plug and Cylinder Heads

Model (Horsepower)

K90/K91 (4hp)

K141 K161 and K181/M8

K241/M10 K301/M12 and K321/M14

K341/M16

K361

KT17, KT17II, KT19, KT19II, MV16, M18, MV18, M20 and MV20

Spark Plug Torque Value

<- 234 in. lb. / 20 ft. lb. ->

Cylinder Head

Torque Sequences and Torque Values

Note: Torque bolts only once to specs. No need to retorque.

15 ft. lb. / 200 in. lb.

15-20 ft. lb. / 180-240 in. lb.

25-30 ft. lb. / 300-360 in. lb.

25-30 ft. lb. / 300-360 in. lb.

25-30 ft. lb. / 300-360 in. lb.

15-20 ft. lb. / 180-240 in. lb.
ALWAYS lubricate threads with motor oil, and gently torque head bolts/nuts in a cross-pattern sequence so the head will not become warped or to prevent from cracking the head!

If the torque value(s) are shown only in inch pounds (in. lb.), and the only tool you have is a torque wrench that shows in foot pounds (ft. lb.), you can convert inch pounds into foot pounds by dividing the torque value by 12. Example: if the value is shown in 420 in. lb., then divide 420 by 12 = 35 ft. lb.

When replacing the head bolts, always use grade 8 bolts or heat-treated steel studs with grade 8 nuts and hardened flat washers to equally distribute the load. Because stainless steel bolts have the same strength as grade 5 bolts. Which means if stainless steel or grade 5 bolts are used, the threads may stretch over time, causing a compression leak and/or a warped head, which can cause a burned-out gasket and/or burned-out or warped head. Return To Previous Section or Website.

Billet Aluminum Cylinder Head from Midwest Super CubIf you're planning to use a big cam with a lot of valve lift than a stock head can handle, then it's time to install a machined billet aluminum cylinder head. A billet head is just some 6061 or 7071 [hard material] aluminum that's had the combustion chamber and valve cavities machined out on a milling machine. Stock heads do well in some cases, but in a high-performance situation, more power and better flow can be had with a specially designed combustion chamber. Billet heads don't necessarily provide a higher compression ratio, they're just made of thicker metal to allow more room for the valves to open more. That's why most professional engine builders prefer to make a head from thicker metal and create a specially designed combustion chamber that's more efficient than a factory head.

When a billet head is purchased new, they are just a flat piece of thick aluminum. Before the combustion chamber is machined out, the bolt holes drilled and the spark plug hole drilled and tapped, no previous machining should have been done to it

After machining the combustion chamber and valve cavities, hand-sand it with 80 grit emery cloth. Make it as smooth as possible. The smoother, the better.

A thick billet head won't warp like the thinner factory OEM ones sometimes do. Therefore, the head gasket won't blow out. Billet heads are either 1" thick for an average lift cam (up to .500" lift) or 1-1/4" or slightly thicker for a higher lift cam (more than .500" lift). Thicker material must be used with a high lift cam so there'll be enough metal for the spark plug threads and to prevent the metal from cracking or blowing out under full throttle/high-compression. When choosing the thickness of a billet head, consider the thickness of the head gasket material when it's compressed, tip of the valve head(s) if they're above the deck, cam lift and of course clearance over the valves. After considering this four items, remember that the threads for the spark plug will need at least 3/8" thickness.

And billet cylinder heads don't stay cool because most of them have no fins machined in the head and most steel flywheels have no cooling fins. Besides, most pulling tractors don't run long enough to do any serious overheating and when they burn methanol fuel, the methanol will help cool the combustion chamber as the engine runs.

How to Make a New Spark Plug Hole -

Spark Plug Thread Hole Chaser and Spark Plug Hole TapWhen making a new hole and cutting threads for the spark plug, use a 1/2" drill bit (for 14mm threads) to bore the hole, then use a 14mm x 1.25 pitch spark plug tap to cut the threads. Be sure to drill the hole and cut the threads perpendicular to the head! If the hole is drilled crooked or the threads are cut crooked, the spark plug won't seat (seal) a full 360º and loss of compression will result. A spark plug tap can be acquired on eBay, at a local hardware store or machine shop/steel supply company. Don't use a spark plug thread hole chaser to cut new threads. They're made to clean carbon deposits and renew damaged threads.

Repairing Stripped 14mm Spark Plug Holes -

If 14mm spark plug threads are stripped-out in a cylinder head, a stainless steel Heli-Coil thread repair insert or a special-made mild steel solid thread repair insert can be installed. For cleanliness and to prevent metal cuttings from entering the combustion chamber, which will cause severe engine damage and wear, the cylinder head must be removed before installing the insert! By the way - a mild steel or stainless steel thread insert is absolutely, without a doubt, much stronger than any aluminum threads. To install the solid thread insert...

  1. Cut oversize threads in the head with the supplied tap that came in the solid insert 14mm spark plug thread repair kit. Make sure the threads are cut perpendicular with the head to prevent a cocked or crooked installed spark plug.
  2. Apply high temperature/high strength liquid threadlocker on the threads of the insert and on the threads in the head.
  3. Install the insert on the spark plug threads with the flared end toward the spark plug body, and install them together in the head, and tighten securely. Allow the threadlocker to cure for about 30 minutes. It usually fully cures in 24 hours at room temperature.
  4. Remove the spark plug, and use a 5/8" tapered punch and medium size hammer to expand the insert from inside of the combustion chamber to lessen the chance of it coming out when removing the spark plug.
  5. If necessary, use a 14mm x 1.25 pitch spark plug tap to repair the threads on the end of the insert after using the punch.

The Heli-Coil insert doesn't require threadlocker because its "spring-like" action expands outward against the threads in the head, keeping it intact with the head.

Or contact a-1 Miller's Performance Enterprises if you are not able to repair stripped spark plug threads.

If a stripped 14mm spark plug threaded hole is too large for the thread repair insert as mentioned above È, and/or if an attempt was made to repair a stripped spark plug hole with a thread insert that was inadvertently installed not perpendicular with the head (crooked or cocked), or if a smaller (14mm) spark plug threads is to be used in a head originally with an 18mm spark plug hole (such as a Wisconsin engine), the hole can be repaired correctly or converted to smaller 14mm threads with a 1/2" NPT mild steel Allen pipe plug. Here's how to do it: An innovative concept by Brian Miller, because nobody else advertise this type of repair.

  1. If necessary, enlarge the spark plug hole with a 23/32" drill bit for the 1/2" NPT taper pipe tap. For accuracy, this is best performed with the head firmly clamped on the table of a drill press or vertical milling machine.
  2. Cut threads in the hole perpendicular to the head with a 1/2" NPT taper pipe tap. USE CAUTION! Don't get carried away the first time! Meaning don't cut the tapered threads too big or the pipe plug will set too deep in the hole! The length of the tap should go about 3/4's in the hole, which should allow the plug to set midway in the hole when tightened. Cut just a little bit, then install and tighten the plug in the hole to check the depth. Remove the plug and cut the threads a little deeper if necessary.
  3. Install a 1/2" NPT mild steel Allen pipe plug in the head with high temperature/high strength liquid threadlocker and torque to 54 ft. lbs. to permanently secure it in place
  4. Bore the center of the pipe plug perpendicular to the head with a 1/2" drill bit. For precision accuracy, this is best performed with the head firmly clamped on the table of a drill press or vertical milling machine.
  5. Face both ends of the plug so it'll be flush with the outside of the head for the spark plug to seal against the pipe plug, and be even with the surface of the combustion chamber. For precision machining, this is performed using a small diameter end mill with the head firmly clamped on the table of a vertical milling machine.
  6. Cut threads in the pipe plug perpendicular to the head with a 14mm x 1.25 pitch spark plug tap for 14mm spark plug threads (most common). To accurately start the thread-cutting process, this is best performed with the head firmly clamped on the table of a drill press or vertical milling machine. Slowly rotate the spindle by hand just to start the threads in the hole. Do not turn on the machine!
  7. Chamfer the threaded hole inside and out with a chamfering bit to remove any sharp edges.
  8. If preferred, apply anti-seize on the threads of the spark plug, install the spark plug in the head and securely tighten.

As the last resort, stripped threads in an aluminum head can be welded up with aluminum welding, refaced (milled flush), then drilled and tapped for installation of the spark plug.

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If need any of the services performed below, please contact A-1 Miller's Performance Enterprises | 1501 W. Old Plank Rd. | Columbia, MO 65203-9136 USA | Phone: 1-573-256-0313 (shop) | 1-573-881-7229 (cell). 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.) A-1 Miller's shop is open to the public from 9am to 5pm, including weekends (except Holidays). Please call before coming so I'll be here waiting for your arrival. Fax: 1-573-449-7347. E-mail: pullingtractor@aol.com. Directions to our shop | 1501 West Old Plank Road, Columbia, MO - Google Maps or Map of 1501 West Old Plank Road, Columbia, MO by MapQuest. | 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.
Stripped Spark Threads Repair Service - No need to purchase another cylinder head! The repair services below also includes resurfacing of air-cooled small engine cylinder head to remove warpage and restore flatness.
  • Install Heli-Coil thread repair insert for normal stripped spark plug hole. $10.00 each for parts and labor, plus return shipping & handling.
  • Install 1/2 NPT steel pipe plug for oversized stripped spark plug hole up to 5/8" diameter, and machine pipe plug for installation of new spark plug threads. $40.00 each for parts and labor, plus return shipping & handling.
  • Weld up hole larger than 5/8" diameter, and machine aluminum welding for installation of new spark plug threads. $60.00 each for parts and labor, plus return 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 small 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.
  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 side clearance.
  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. Use modeling clay (such as Play-Doh) to measure the clearances between the valves and the head. Apply motor oil on each valve and in the head (valve cavities) to prevent the clay from sticking to either surface. Fasten the head with the head gasket to the block, then crank the engine over slowly by hand one full revolution so the valves can compress the clay. Remove the head and use the depth gauge on a dial or digital vernier caliper to carefully measure the thickness of the clay. There needs to be a minimum of .100" clearance between the valves and the head.
  3. Place the head and gasket on the engine and tighten down a couple of head bolts.
  4. Rotate the crankshaft slowly by hand 360º. 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 360º, remove the head and use the depth gauge on a dial or digital vernier 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. Return to previous paragraph È

How to make your own modeling clay (Play-Doh):

Directions: Thoroughly mix flour, salt and cream of tartar or alum. Boil liquids together. Pour in dry ingredients and stir together. Knead and add flour as needed. Return To Previous Paragraph È

When machining the valve cavities in an OEM stock head or in a billet head when installing a cam with more valve lift, use the following clearances:

FYI - I've milled several stock heads as much as 1/8" and they did well at the pulls. However, using methanol on a cool day could blow the combustion chamber out on a stock head that's been excessively milled for valve clearance. I've had this happen on my 12hp Super-Stock pulling tractor once. I was going down the track, engine running excellent, then all of a sudden "PUFF!" went the head.

INFORMATION!

USE CAUTION BEFORE INSTALLING A BILLET HEAD!

If you're popping the piston out of the cylinder beyond the thickness of the [compressed] head gasket, and the head isn't cut out for piston clearance (there should be a minimum of .030" clearance between the piston and head), this could (or more likely, will) cause the piston to hit the head. When this happens, the upper half of the bearing insert will become flattened, and this will cause the connecting rod to run loose on the crank journal. And when this happens, the engine will knock, the rod bolts will stretch and the rod and/or bolts will eventually break. These series of events are a common problem when using a billet head. So always check the clearance between the piston and head before using a billet head. And make sure that there is at least .075" clearance between the spark plug tip and the exhaust valve when the valve is at its highest lift point, and .075" clearance between the intake valve and head! By the way - on the late model cylinder heads that some single cylinder Kohler engine models use have the spark plug located directly over the exhaust valve. They did this to gain more power by maintaining the heat in a certain area and to keep incoming raw fuel from fouling the spark plug.

É Below is a drawing and picture of a custom designed combustion chamber in a billet head. ÊCustom Designed Combustion Chamber by Vogel Manufacturing Company

Picture by Vogel Manufacturing Company

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

The Kohler engine model 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. 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. And the reason the guides loosen is because the hole they're pressed into is very short. In other words, there's not much metal (in the head) to secure them in place 100%.

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 the lower outer edge of the new seat in a small metal lathe for easier installation into the counterbore.
  5. Apply high temperature/high strength liquid threadlocker 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 in the head 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.

Advertisement:
If need any of the services or parts below, please contact A-1 Miller's Performance Enterprises | 1501 W. Old Plank Rd. | Columbia, MO 65203-9136 USA | Phone: 1-573-256-0313 (shop) | 1-573-881-7229 (cell). 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.) A-1 Miller's shop is open to the public from 9am to 5pm, including weekends (except Holidays). Please call before coming so I'll be here waiting for your arrival. Fax: 1-573-449-7347. E-mail: pullingtractor@aol.com. Directions to our shop | 1501 West Old Plank Road, Columbia, MO - Google Maps or Map of 1501 West Old Plank Road, Columbia, MO by MapQuest. | 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.
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. And I don't sell the aftermarket bronze valve seats that are installed in the K361 heads because they are machined from scratch. Due to the molded-in tongue and groove installation of the OEM valve seats by Kohler, the outside diameter of the bronze seats can vary a lot according to how much trouble it is to remove the OEM valve seats from the head. Contact Elson Nichols at 573-449-0983 for more details of the bronze valve seats. Click here for cylinder head bolt torque specs.
  • 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 on wide wide flat sanding belt or large diameter disc sander to remove warpage and restore flatness. $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.

Gasket kit to reinstall the K361 cylinder head on the engine. Includes: head gasket (part # 45 052 02-S; $24.00), rocker arm housing gasket (part # 45 041 14-S; $14.00), rocker arm housing cover gasket (part # 45 041 09-S; $5.75), two pushrod tube O-rings (part # 45 153 01-S; $2.00/two), and intake tube mounting gasket (part # 271030-S; $1.00). All parts total: $46.75, plus 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.)

  • High quality aftermarket. $42.00 each, plus shipping & handling.
  • OEM Kohler part # 45 755 06-S. $110.00 each, plus shipping & handling.

New Intake Valve for Kohler engine model model K361 (18hp OHV). Dimensions: head diameter: 1.437"; overall length: 4.175"; stem diameter: .3095"; face angle: 45º.

  • OEM Kohler part # 45 017 01-S. $126.10 each, plus shipping & handling.

NOTE: A new exhaust valve for Kohler engine model model K361 (18hp OHV) is part # 45 016 02-S, and 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 new old stock (NOS). The dimensions for machining an exhaust valve from a larger one are: head diameter: 1.437"; overall length: 4.158"; stem diameter: .309"; face angle: 45º. (The OEM [US] 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.)

Valve Guides for Kohler engine model model K361 (18hp OHV) cylinder head.

  • Intake Valve Guide. OEM Kohler part # 45 316 02-S. $12.40 each, plus shipping & handling.
  • Exhaust Valve Guide and Seal Kit. OEM Kohler part # 45 755 11-S. $56.95 each kit, plus shipping & handling.

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 RPM. 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 20% bigger than the exhaust valve, which would make it 1.68". And this is way too big for the K361 head.

If an OHV aluminum block engine blows smoke out the exhaust upon start up then quits smoking, and/or oil is forced out the oil fill tube, this is likely the signs of a warped cylinder head, which results in a blown head gasket. The problem is caused by normal engine heat from the first time the engine is ran. To fix this, remove the head, resurface it on a wide sanding belt or large diameter disc sander to remove warpage and restore flatness, install a new head gasket, torque the head bolts to specs in the correct sequence, and readjust the valve clearances. It shouldn't warp again.

How to Remove a Broken Head Bolt -

Use a "centering drill," which is a stubby drill bit that creates a hole exactly in the center of a stud. Then use a 5/16" carbide-tip drill bit to drill the broken stud out, and then use a 3/8-16 NC tap to clean the threads. If you feel this is too much for you, you can take your engine to a reputable machine shop and have them do this for you.

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If you wish to have your Kohler stock or pulling engine dyno-tested, please contact A-1 Miller's Performance Enterprises | 1501 W. Old Plank Rd. | Columbia, MO 65203-9136 USA | Phone: 1-573-256-0313 (shop) | 1-573-881-7229 (cell). 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.) A-1 Miller's shop is open to the public from 9am to 5pm, including weekends (except Holidays). Please call before coming so I'll be here waiting for your arrival. Fax: 1-573-449-7347. E-mail: pullingtractor@aol.com. Directions to our shop | 1501 West Old Plank Road, Columbia, MO - Google Maps or Map of 1501 West Old Plank Road, Columbia, MO by MapQuest.

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For performance testing engines up to 200hp at speeds up to 12,000 RPM. The only engine dyno service in Missouri for Kohler pulling engines! Now set up and fully operational in our shop, every competition pulling engine that we build will be dyno-tested, fine-tuned and adjusted on our Stuska water brake dynamometer with data logger before it leaves our shop to make sure it is producing maximum horsepower and torque, or customers can rent dyno time and make adjustments or changes to their engines and print-out the results. Proposed Engine Dyno Rental Fee: $50.00 per hour run time. No setup fee for Cub Cadet engines with a 3- or 6-pin/stud clutch driver. An adapter may need to be needed or fabricated for other makes and models of engines.

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