Farmall M falls flat on its face

FarmallKeith

New User
I was at a pull with my farmall M this past weekend. My tractor started out well but towards the end I run out of power. I was told by another IH guy to check my pistons to see if there flat tops. what can I do to fix this tractor? Im on a small budget we have a baby on the way. thank you keith
 
That's the sad part about tractor pulling. Even when pulling in the basic stock class, you still have to throw money at the tractor in order to be competetive. A guy would think that a good running M, that can pull a 3-16s plow all day long with nary a whimper would also do quite well on a pulling track, but when the competition shows up with a tractor that they've just spent about $3,000 on just the engine, the guy with shallow pockets just doesn't stand a chance.
 
Stay at home and play with the baby's mother and forget about having any extra money for anything till after the child turns 21 or 30 years of age.
 
The pistons are not flat heads the have a large dome. I did a compression test. From the front cylinder 100psi 125psi 105psi 110psi. Im also going the check out the govenor. Checking for broken springs debris build up make sure thing moves. Anymore ideas?
 
I will check the timing. This tractor starts right up.but does not idol. It is Always at high RPM's. I had the carb redone. Befor I bought it the top end was redone do to coolant in the oil.
 
An engine not idling can be caused by ignition problems. The ignition can be so screwed up it requires so much throttle to run that it never closes up and uses the idle jets.

Check the point gap first, then timing.
 
It might have a intake manifold leak.This will also cause a high idle.Does it miss or cut out or just pull down. I have pulled against what I believe are stock M"s and they usually don"t power out unless above 6100 lb class.
 
The trouble is even if it works good enough all day long what you need at the track is "everything at once" that a tractor couldn't keep up for long.
 
I have checked the manifold for leaks did not find any or any cracks all gaskets seem like they're in good shape.I have pretty much variable midrange. I was pulling a stone boat 4,00lbs 40' was a full pull. I dies out at 38' almost stalled out.
 
Open that main jet adjusting screw to enrich the fuel mixture near the bottom of the carburetor.
My garden tractor and Toro mower have that feature. Hal
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Cylinders are supposed to be within 10% of each other. It appears to me that one cylinder was fixed, the 125 one. The other 3 have normal wear. Number 1 is 25% less, 3 is 16% less. New flat tops should give about 120-125 psi. I don't know what psi your domed pistons are supposed to have, but the IH fire craters are about 135. I know zero about pulling, but your engine has some wear on it and what you may not notice in the field shows up in pulling.
 

You did not say how far you pulled. If you got over 100 feet or so, you did well. An old M with standard tires and a drawbar isn't going to take it out to a full pull range. If you change out your low gear , you will double your HP.
 
Reset the timing. Had a 72 chevy truck that ran like CRAP! No power, horrible mileage. Purchased a timing light and got the chiltons from the library checkout. Set the timing and it became a whole new animal. Talk about night and day. Had a pro mechanic set the timing on my Farmall M after I rebuilt the cylinders. He used a dwell meter to determine top dead center and all that great stuff. The tractor popped off before you could say boo, and had great power.
 
If all else is well(timing, intake seal,etc), adjust your fuel mixture as mentioned. A stock M can compete just fine in STOCK classes against other stock tractors and you can have years of fun.
It will do fine in classes that are regulated to be less than 4 mph. Pull in first gear in that case. I've seen guys with M's try to pull 2nd gear in heavy classes and run out of power.
 
(not a flame)The gears are not associated with Horsepower. One can make more drawbar pull with a super low gear, but it will be at a slower pace (assumes it will be weighted to do so). Jim
 
Well, this summer, I pulled my 1938 F30 narrow tread in the 5500 class and the 6500 class. Both times, I ran out of traction just as the governor kicked in. I know 5-10 feet is alot in a tractor pull, but that old F30 stayed within 10 feet of the SM's and similar. They ran out of power, I ran out of traction. Go figure.

I have done nothing to that engine except tune it up, adjust the valves and redid the carb (stock).

a tuned up M, that isn't "tired" will pull and pull well. Get the timing right, make sure the valves are seating and adjusted correctly. Clean, correctly set carb. Let 'er rip. she will run good. If she is tired and a little worn out, not so much.

If you are truly looking to spend a little money and get the biggest bang for the buck. New rings, hone the sleeves, valve job, and get the carb/governor right. she will surprise you.
 
I am reading the service book
about the governor. I looked at
the settings on my tractor. I
think some one was playing with
it. The high idle speed
adjusting screw does not touch
the tuck the case or stop. And
the same with the low speed
screw. The spring just hangs
there on the idol setting of the
throttle. I have a picture of
it. I can't load it off my
phone.it will only let me email
it.
 
(quoted from post at 17:12:03 10/14/13) (not a flame)The gears are not associated with Horsepower. One can make more drawbar pull with a super low gear, but it will be at a slower pace (assumes it will be weighted to do so). Jim

Come on now --think a bit. What is the purpose of a gear reduction unit. If you change 1st gear from a 3 mph gear to a 1 mph gear, what have you done?
You have effectively doubled the pulling power. In a round about way increased the HP.
 
Ive got an H and it would fall on its face too even with high domed pistons. My first step was the governor. I had a friend help me make a good governor out of 3 junk ones. We replaced the bearings and seals and used the weights that were the least sloppy. That helped an immense amount. I still did not have the power to pull it even in low gear once we got up to about 190%. I talked to some people and the said that I probably had the old all fuels (distillate) head. The head has a lot bigger combustion chamber. I bought a 300 head and had it milled .110" and it made a world of difference. I cac go up to 190% in second gear before dropping. In your case I believe you could go with either a 400 or a 450 head.
 
Did you get the tab aligned correctly with the notch when you put the carburetor back on the tractor?

If you miss to one side, it will not rev up.
If you miss to the other side, it will not idle down.
 
Yes I have checked that tab. I
going to check that tab once
again. I'm also going to check
the valves And adjust if needed.
I'm also going to check the head
to make sure it has the gas
casting number on it of 8696. I
think that's right?
 
I am checking in valves the head # is 8080db is this the right head? Also can any one give me some info on this block the serial number Is FBKM 114526. The tractor serial number Is FBK 115876 XL. Any info would be great
 

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