Information
About Cylinder Heads For Kohler Engines
Identification of Kohler K-series and Magnum Single Cylinder Engine Cylinder Heads -
(Updated 10/24/20)
The cylinder head with the cooling fins shown to the right
is used on Kohler K-series engine models K141, K160/K161, K181, and Magnum
M8. The first air-cooled head was introduced in 1952 on the K141. Being there
are 14 different part numbers for these heads, they are virtually the same
with very little difference. The OEM Kohler part numbers for these heads
are: 230402-S, 230403-S, 230990-S, 231200-S, 230451-S, A-230770-S, 41 015
01-S, 41 015 02-S, 41 015 04-S, 41 015 06-S, 41 015 07-S, 41 015 08-S and
41 015 09-S. These heads are discontinued from Kohler.
The cylinder heads for the water-cooled Kohler engine models L161 (with specification numbers 4149F, 4150F, 4152E, 4166F, 4167F, 4168E, 4168G, 4168H, 4173E, 4192E, 4194F, 4195F, 4199G, 4199H, 41101F, 41109F, 4110F, 41117F, 41131F and 41137F, which are all generator engines) and L181 (with specification numbers 42583H, 42594H, 42597H, 42626H, 42723H, 42745H, 42746H). The part numbers for these heads are: 230451-S; 230563-S (uses a bellows type thermostat); 41 453 01-S (uses a wax type thermostat); and 41 015 05-S. The L161 and L181 engines were only used with a generator. These heads are also discontinued from Kohler. None of these heads should be milled to raise the compression in an attempt to increase the power output because the valves are already very close to the head when they are at full lift. All that can be done is resurface it on a wide flat belt sander or large diameter flat sanding disc to remove warpage and restore flatness to prevent a blown or leaking head gasket. If one don't have their own belt/disc sander, most automotive machine shops and carpenters have one. Do the repair job right the first time and it won't have to be done again later.
The First Generation Cylinder Head -
This cylinder head was manufactured
by Kohler from the early 1960s until 1971 and was available only on engine
model K241 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head was originally made for and came on the very early K241 engines. It'll
also work on the Magnum engine model M10, K301/M12 engines and the early
K321/M14 engines with a 1-1/8" exhaust valve. But being the later K321 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 K301 or K321 engine,
Premium, race gas, E-85 or methanol fuels must be used, or the engine will
overheat and wear out prematurely. The compression ratio is 7:1 when used
on a K241/M10 and 8.6:1 when used on a K301/M12. If this head was used on
a K321/M14, it would yield a 9:1 compression ratio. And LP heads did not
come on nor will they fit the K341 engines. This head requires 2-1/4" length
bolts with no mounting bracket(s) under the bolt, and 2-1/2" length bolts
with [gas tank] mounting bracket or other bracket(s) under the bolt. 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.
This Kohler cylinder head with the numbers 235461 embossed in it is designed for the K241, K301 and early K321 engines with the small (1-1/8") exhaust valve. To use this head on a newer K321 engine with the larger (1-3/8") exhaust valve, the valve shrouding area in the head will need to be milled out for adequate clearance.
NOTE: This particular head was originally designed many years ago ONLY for the K241 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 K241, 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 K301 engine came into production, because this engine requires a lower compression head. So if you need an LP head, remember, they came only on the very early K241 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 Cylinder 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 K241 and K301 engines, before the K321 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 misidentified 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 K241 and K301 engines, but would not work on the K321/M14 engine because of its' larger exhaust valve (it was manufactured before the K321 engine went into production) unless reduce the size of the exhaust valve on a K321 to a 1.125" (same as a K241 and K301) 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 K241 and 6.6:1 when used on a K301. If this head was used on a K321 (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.
NOTE: The older head like this has the tall bolt hole bosses. And the newer head with the same combustion chamber and spark plug location has the bolt hole bosses recessed in the head for better cooling. The early heads with the tall bolt holes with no mounting brackets or plates under the bolt heads require 2-1/4" length bolts, and engines with a [gas tank] mounting bracket or other brackets/plates require 2-1/2" length bolts. The head with the recessed bosses require 3/4" tall spacers on the head bolts (and longer bolts) when using a gas tank bracket or other kind of mounting bracket. The reason Kohler redesigned the head with low bosses is so more air can flow over the head bolts instead of around the bosses for better cooling of the head.
The Third Generation Cylinder Head -
The third head manufactured
by Kohler has a low compression (depressed) D-shaped combustion chamber.
And unlike the sought-after, but misidentified 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 K241/M10,
K301/M12 and K321/M14 engines because the exhaust valve area was made bigger.
(It was manufactured when the K321 engine went into production.) The compression
ratio is 5:1 when used on a K241/M10, 6.1:1 when used on a K301/M12, and
6.6:1 when used on a K321/M14. 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 K241, K301 and K321 engines.
OEM Kohler part # 237827-S.
NOTE: The older head like this has the tall bolt hole bosses. And the newer head with the same combustion chamber and spark plug location has the bolt hole bosses recessed in the head for better cooling. The early heads with the tall bolt holes with no mounting brackets or plates under the bolt heads require 2-1/4" length bolts, and engines with a [gas tank] mounting bracket or other brackets/plates require 2-1/2" length bolts. The head with the recessed bosses require 3/4" tall spacers on the head bolts (and longer bolts) when using a gas tank bracket or other kind of mounting bracket. The reason Kohler redesigned the head with low bosses is so more air can flow over the head bolts instead of around the bosses for better cooling of the head.
The Fourth Generation and Newest Style Cylinder 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 misidentified 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 K241/M10, K301/M12 and K321/M14 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 K241 "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 K301/M12 and K321/M14 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 Cylinder Head
-
The K341 cylinder head is in a class all 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 K341 cylinder heads. And ALL K341/M16 cylinder heads have the spark plug located over the exhaust valve. No exceptions. OEM Kohler part # 45 015 09-S. The head too, has the spark plug located directly over the exhaust valve. And there are two reasons why Kohler did this:
Kohler Cylinder Head Identification and Cub Cadet Applications: Kohler K-series engine model K241. OEM Kohler part # 235461, Cub Cadet part # IH-385303-R1. LP head; Discontinued Originally came on the 1965 and earlier Cub Cadet model 100, and other makes and models of garden tractors and small engine equipment. Requires 2-1/4" length bolts (Kohler part # 271077 - Discontinued from Kohler) with no mounting bracket(s) under the bolt head, and 2-1/2" length bolts (Kohler part # 235175-S) with [gas tank] mounting bracket or other mounting brackets/plates under the bolt head. Kohler K-series engine model K241. OEM Kohler part #'s 236546-S. Either head originally came on various Cub Cadet models 100, 102, 104, 105, 106, 107, 108, 109 or 1000, and other makes and models of garden tractors and small engine equipment. This head is no longer available from Kohler. Requires 2-1/4" length bolts (Kohler part # 271077 - Discontinued from Kohler) with no mounting bracket(s) under the bolt head, and 2-1/2" length bolts (Kohler part # 235175-S) with [gas tank] mounting bracket or other mounting brackets/plates under the bolt head. Kohler K-series engine models K301 and K321. OEM Kohler part #'s 237670-S (Discontinued from Kohler; or 237827-S. Either head originally came on various Cub Cadet models 122, 123, 124, 125, 126, 127, 128, 129, 147, 149, 680, 1200, 1250, 1282 or 1450, and other makes and models of garden tractors and small engine equipment. Both heads require 1-1/2" length bolts, w/centered spark plug). Kohler K-series engine model K341 (including M16 Magnum engine). OEM Kohler part # 45 015 09-S. Originally came on Cub Cadet models 169 and 1650, and other makes and models of garden tractors and small engine equipment. Requires 1-1/2" length bolts (OEM Kohler part # 25 086 115-S), w/offset spark plug hole. Kohler Magnum engine model M10. OEM Kohler part #'s 237670, 47 015 05-S. Originally came on Cub Cadet model 1050. Requires 1-1/2" length bolts (OEM Kohler part # 25 086 115-S), w/offset spark plug hole. Kohler Magnum engine models M12 and M14. OEM Kohler part # 47 015 06-S. (Discontinued from Kohler; Requires 1-1/2" length bolts (OEM Kohler part # 25 086 115-S), w/offset spark plug hole.)
Compression Ratios for Factory Stock Kohler K-series and Magnum Engines with an OEM Kohler Cylinder Head are as follows:
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,
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.
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 also need to be done. In most cases with a stock-lift cam, there should be adequate clearance once a stock OEM 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 or tap here. Milling of the head will increase the compression ratio about 3/4 of a point. And depending on engine size, this will definitely, without a doubt, add about 1-3 more horsepower and more torque. The engine will have a "snappier" response when the throttle is opened suddenly, and if the engine is in good running condition, it will literally "pull you back in the seat" of a garden tractor when the engine is quickly accelerated. To learn what else can be done to a stock engine to increase it's power output, Click or tap here.
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, then coat it evenly with ordinary
aluminum or silver color spray paint (available at Walmart
or virtually any hardware store), reinstall the gasket, and tighten the head
bolts or nuts (with studs) to the correct torque specs. Normal operating
engine combustion heat will melt the aluminum/silver 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 the same
aluminum or silver color 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. (Hitler
said he was going to dance on the White House steps. Fortunately, that did
not happen.)
When to Use a Copper Head Gasket - Top of Page
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.
Removing a Broken-Off Tap - A threading tap that has broken off in an engine block or metal casting can be very difficult to remove. About all I can tell you is to either take your block to a reputable machine shop to have the tap removed, or go here and try to do it yourself: https://www.google.com/?gws_rd=ssl#q=removing+broken+tap+from+hole. Actually, it's best to use a TAPER hand tap to cut new threads and clean out existing threads. If used correctly, a TAPER tap is less likely to break off. Click or tap here to learn how to cut new threads, the professional way. And OEM Kohler head bolts don't need to be retorqued again 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)...
If a small engine cylinder head is burned out (usually close to the exhaust valve), if it's burned out where the gasket seals, as long as there's no cracks in the head, it can be successfully welded up, machined flat, the bolt hole redrilled and be put back into service. The following items are what causes cylinder head burn-out...
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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 will not 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 Remove Carbon Deposits from the Combustion Chamber in a Cylinder Head - (added 11/6/16)
How to Make a New Spark Plug Hole -
Repairing Stripped 14mm Spark Plug Holes -
The Heli-Coil insert doesn't require threadlocker because its "spring-like" expands outward against the threads in the hole, keeping it intact in the head. Or contact a-1 Miller's Performance Enterprises if you are not able to repair stripped spark plug threads. As the last resort, if the stripped spark plug threads hole in an aluminum head are too large for a Heli-Coil thread insert, the hole can be successfully welded-up with aluminum welding, machined (milled) flush with the surface of the head, then drilled perpendicular with the head, and new spark plug threads tapped for installation of the spark plug.
How to check for proper valve clearance between the valves and cylinder head...
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.
Below Ê is a drawing and picture of a
custom designed combustion chamber in a billet head.
Ê
How to Repair A Loose Valve Seat and Worn or Loose Valve Guides in the K361 Cylinder Head -
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:
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About Installing Bigger Valves in the K361 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. If one don't have their own belt/disc sander, most automotive machine shops and carpenters have one. Do the repair job right the first time and it won't have to be done again later.
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 UNC (coarse thread) 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.
A-1 Miller's Computerized Stuska Water Brake Engine Dynamometer (Dyno) Service with DPM Data Logger Software to Test Horsepower and Torque! | [Top of Page]
Engine Dyno Rental Fee: $50.00 per hour run time from the moment the engine is started. 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. Only engines with the narrow base oil pan can be tested. Engines with the wide base (tall) oil pan cannot be tested at this time. [Return to Previous Section, Paragraph or Website]
If you would like to purchase any of the parts or services listed in this
website, please contact A-1 Miller's Performance Enterprises | 1501 W. Old
Plank Rd. | Columbia, MO (Missouri)
65203-9136 USA | To place an order, please call the number below Ê or send an email with your name, complete and correct postal address and phone number and so I can figure the total with shipping cost and USPS Tracking. For payment options for parts ordered or services performed, or to make a donation to my websites, I accept cash (in person), USPS Postal Money Orders, cashier's checks, business checks, MasterCard, VISA, Discover, American Express (please add 2.5% to the total for the credit/debit card processor's surcharge), Western Union Money Transfer or MoneyGram Money Transfers. (If a part for a specific purpose is special ordered, your debit/credit card may be charged for the full amount or as a deposit right after your order is placed; please do not send your debit/credit card information in email!) Or you can pay A-1 Miller's through PayPal. (My PayPal account name is my email address. And be sure to mention in PayPal a description of what the payment is for.) If sending a money order, please include a note in the envelope with your name, complete and correct postal address, phone number and a description of what the payment is for. My mailing address and phone number are below Ê . I'll make a note of your order, and I may have to order some of the parts, which should take a few days to come in, but I will send the parts to you as soon as I have everything in stock after I receive your payment. IMPORTANT - When sending your part(s) to A-1 Miller's for rebuilding or repair, package everything securely so the item(s) won't get damaged in shipping and please include a note in the box with your name, mailing address, phone number (in case I have any questions) and a description of what you want done. When shipping heavy parts, it's best to put a slightly smaller box inside a larger box, to double the strength and integrity of the package. Because the clumsy "gorillas" or incompetent and uncaring workers that work for certain delivery services mishandle the heavy packages and don't care. And when the work is completed, I'll either call or email you an invoice with the total including shipping & handling.
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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.
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
Reusing Metal-Shielded
Head Gaskets -
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
Regardless of the thickness
of a copper head gasket, these should only be used with a machined billet
cylinder head and for competition pulling. If a copper head gasket is used
with an OEM Kohler cylinder head, it would most likely leak compression between
the head bolts, even when copper silicone is used. This is because all OEM
heads are much thinner than the thicker billet heads, and when the head bolts
(or nuts w/studs) are torqued to specs, the OEM head will flex and press
down a few thousandths of an inch where the head bolts are, and with a copper
head gasket, it will not "clamp down" entirely against the gasket between
the head bolts. The head doesn't necessarily become warped, it just flexes
or bends. Therefore, it's best to use the "cushiony" OEM Kohler type of head
gasket with an OEM head to compensate for the flexing or bending and seal
better, even for competition pulling.
For dirty or rusted engine blocks,
to prevent a blown or leaking head gasket, besides resurfacing the head(s)
and cleaning the deck of the block, due to dirt/debris that gets accumulated
in the threads for the head bolts, the threads may need to be cleaned out
with the appropriate size tap (5/16-18 UNC (coarse thread) for Kohler engine
models K141, K161/K160, and K181/M8 engines; and 3/8-16 UNC (coarse thread)
for Kohler engine models K241/M10, K301/M12, K321/M14, K341/M16 and K361
engines) to get the head to fully compress the gasket when the bolts are
torqued to specs. It's best to use a TAPER hand tap. A TAPER tap cleans threads
more thoroughly [than a PLUG tap] and is less likely to break off in the
block when in use. Then a PLUG tap can be used to clean the threads deeper.
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.
Phone: 1-573-256-0313 (shop) | 1-573-881-7229 (cell; text or when leaving
a voice message, please speak slowly and clearly). 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.)
E-mail: 
Repair loose valve seat with
a new bronze valve seat. FYI - A replacement steel valve seat will
loosen after a short time in an aluminum cylinder head, even if it is
professionally installed. But when professionally installed, a replacement
bronze seat will not loosen because it grips or adheres to aluminum much
better than steel. Plus, bronze is harder than cast iron. $75.00
each for parts and labor, plus return shipping & handing.
Gasket Kit to Reinstall
K361 Cylinder Head on Engine. (Updated 5/27/19)
High quality
aftermarket. Discontinued from Kohler. Replaces Kohler part # 45 052 02-S.
$24.00 each, plus shipping & handling.
Complete engine rebuild gasket
set w/oil seals for Kohler K-series model K361 cast iron block single cylinder
OHV engine. High quality aftermarket. Discontinued from Kohler. Replaces
Kohler part # 45 755 06-S.
High Quality Aftermarket K361
Valve. Can be used as intake or exhaust valve. Heat-treated, hardened steel.
Dimensions: head diameter: 1.437"; overall length: 4.165"±; face angle:
45º. Has 8mm chrome-plated stem. Requires 8mm
Valve Guides for Kohler engine
model K361 cylinder head.
Resurface air-cooled
small engine cylinder head on large disc sander or wide, flat belt sander
to remove warpage and restore flatness, and deburr sharp edge around combustion
chamber. $10.00 labor, plus return shipping & handling.
A-1 Miller's Machine Shop
Service - Install Heli-Coil thread repair insert in stripped-out 14mm
spark plug hole if not larger than 5/8" in diameter. No need to purchase
another hard-to-find and high dollar cylinder head that's in good condition.
304 stainless steel w/200,000 psi tensile strength. Labor includes resurfacing
of air-cooled small engine cylinder head on a wide belt sander to remove
warpage and restore flatness. IMPORTANT: Torque spark plug to 180-240
in. lb. or 15-20 ft. lb. $15.00 each for parts and labor, plus
return shipping & handling.
Cylinder head gasket. Fits
Kohler flathead engine models K90/K91. Approximately .050" compressed thickness.
Doesn't need to be retorqued again once hot. 
Cylinder head gasket. Fits
Kohler K-series and Magnum flathead engine models K141, K160, K161 and K181/M8.
Approximately .050" compressed thickness. Doesn't need to be retorqued again
once hot. 
Cylinder head gasket. Fits
Kohler K-series and Magnum flathead engine models K241/M10, K301/M12 and
K321/M14. Approximately .050" compressed thickness. Doesn't need to be retorqued
once hot. 
Cylinder head gasket. Fits
Kohler K-series and Magnum flathead engine models K341/M16. Approximately
.050" compressed thickness. Doesn't need to be retorqued again once hot.
Cylinder head gasket. Fits
Kohler engine model K361. Approximately .050" compressed thickness with steel
fire ring. Doesn't need to be retorqued again once hot.
Cylinder Head Gasket. Fits
Tecumseh engine models VH80, HH80, VH100 and HH100. Approximately .050"
compressed thickness. Doesn't need to be retorqued again once hot. OEM Tecumseh
part # 32000B.
Cylinder head gasket. Fits
Kohler KT-series and Magnum opposed (flathead) twin cylinder engine models
MV16, KT17, KT17 Series II, KT19, KT19 Series II, M18, MV18, M20 and MV20.
Approximately .050" compressed thickness. Doesn't need to be retorqued again
once hot. 
Cylinder head gasket. Fits
Kohler opposed (flathead) twin cylinder engine models K482, K532 and K582.
Approximately .050" compressed thickness. Doesn't need to be retorqued again
once hot. 
OEM Kohler Cylinder Head Studs
for Kohler engine models K241/M10, K301/M12, K321/M14 and K341/M16. Dimensions
of each stud: 3/8-16 UNC (coarse thread) threads; 3-1/4" overall length;
short threaded length: 5/8"; long threaded length: 1-7/8". IMPORTANT:
As with any threaded stud, apply
Steel Spacer for Studs Above.
Use with OEM Kohler single cylinder engine cylinder heads with the recessed
bolt hole bosses when using a gas tank mounting bracket or other kind of
flat bracket. Replaces discontinued Kohler part #'s 25 112 14-S and X-400-71-S.
Dimensions: 13/32" i.d. x 5/8" o.d. x 23/32" height.
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 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
Use a narrow, steel blade putty
knife (with a stiff blade) or paint scraper to remove the carbon deposits
from the combustion chamber (and from around the valves and from the top
of the piston). Be sure the putty knife or scraper has a sharp edge, too.
Don't worry about scratching the surface of the combustion chamber either.
The tiny scratches will cause no problems. If the putty knife or scraper
can't easily remove the carbon, soak the head in plain water at room temperature
for a few days. This will soften the carbon and then it should be a lot easier
to remove.
When
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
If 14mm spark plug threads are stripped-out in a cylinder head,
a stainless steel
How
to locate where to machine the cylinder head for the valves...
If the crankshaft rotates freely
after 360º, remove the head and use the depth gauge on a dial or digital
Valve Guides for Kohler engine
model K361 cylinder head.
For performance testing of 10-16hp
single cylinder Kohler stock or competition pulling engines at speeds up
to 12,000 RPM. 100% accurate, customers can rent dyno time, fine tune and
make adjustments or changes to their engines to gain maximum horsepower and
torque, and print-out the results so their tractor(s) will be truly competitive
on the track. With an engine dyno, the puller can adjust their engine to
get maximum horsepower and torque, and gear their tractor appropriately to
have an advantage over the competition. NOTE: A fresh-built engine may
not produce full power until it's broke-in. This is when the valves wear-in
with the seats to completely seal in the compression. The rings will likely
hold the compression, but the valves may leak slightly until they wear into
the seats. This is normal for all engines and may take several hours or pulls
to happen, then the valves will be able to hold full compression. Lots of
pullers tell A-1 Miller's after I've built their engines that it seems to
pull stronger every time they pull it.
Coming Soon - Detailed Illustrated
Plans on How to Construct a Professional Pull-Back and Self-Propelled Garden
Tractor Pulling Sled. FYI - The
professionally-built self-propelled pulling sled is the only one I've ever
built (click the picture to the right to see a larger image of this sled),
and I got it right the first time, with very few changes or modifications
that had to be made to it. I guess I'm just one of those kind of guys that
knows what he's doing. Pullers really like pulling our sled, too. They say
it's the best sled they've ever pulled. (Not bragging, just stating a fact.)
By the way - Track Master sled is engineered so well (by Brian Miller), that
other sled builders/owners have copied my well thought-out and proven design.
And I do appreciate them acknowledging my intelligence. Anyway, I have lots
of work to do in my shop and I work on the sled plans in my spare time. As
soon as my plans with an inventory list of parts to use are perfected, I'll
post the update in my websites with the prices of the plans. Remember -
Perfection takes time. If it's worth having, it's worth waiting for. Also,
I plan to acquire a bigger shop and may build high quality garden tractor
pulling sleds in the future to offer for sale. Please call 573-256-0313 (shop)
or 573-881-7229 (cell; text or voice message), or email
To make a payment to A-1 Miller's through PayPal,
go to PayPal's secure website (
Or to
make a payment to me (pullingtractor@aol.com) in the US through the Venmo
app, please tap this link: 
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