Farmall M fouling plugs

My 51' Farmall M with a new set of spark plugs will start right off with no problems. However, with about 8 to 9 hours of use, it will die and not start. Upon removal of the plugs, I see a thick coat of powdery carbon. The guys at O' Reilly's say the carbon is from running too rich a mixture. Is this true and how do I keep from running too thin and damaging the pistons? Replacing plugs are cheaper than pistons.

I had the same problem.. Found out my float was sticking so you might take your carb off, empty the fuel from it and shake it to hear if the float going up and down. If that is ok go with a hotter plug. An Autolite 3116 or Delco c86 is standard for a Farmall. I would put in a Delco C87 which is a hotter plug. Finally if that doesnt work you can buy anti foul spark plug tips to put on your plugs. You can get those at any autoparts store. Hope this helps

When running, there are two adjustments. A high speed power screw, and an idlew screw.
The high speed is set (from where it is) by opening the throttle wide open, then screwing the adjuster screw front bottom of carb, inward until the RPM dops a little, and it runs lean. Then turn outward until it picks up max RPM and is smooth. Then idle it down, and open it again. if it stumbles and bogs, it needs a bit richer mix. Open the high speed in 1/4 turn increments till it opens W/O stumbling. This is a starting place for High Speed.

Now Idle it down and turn the idle richness screw (up near the throttle, but not the throttle stop screw) It is richer in leaner out. sSo start by turning it out (again till RPM drop and roughness begins. Turn it in until best idle is found with no black smoke. Lean it (turn out) until it just is noticably slower, and then out 1/4 turn.

Now do the High speed setting as described abofe one more time (they affect each other, and must be done to a ballance.

If the idle speed is too high, adjust it down and then redo the idle and high speed again.

When pulling a real load, the high speed screw may need to be turned out (maybe 1/2 to one turn for good power and to avoid lean condition. Then screwed back that amount inward when not being used hard. Best of luck, JimN

If it is in fact running that rich you have a problem and that rich could be causing wash down in the cylinders which is as bad as running to lean or even worse. I would take the main jet and screw it all the way in, then back it out about 4 turns. Adjust for max. power with no black smoke and fine tune it from there to the point you have good looking plugs and good power. Running the rich is probably hurting your engine because the extra gas is washing the oil off the cylinders and hurting the rings and pistons
Hobby farm

Sounds like it is running too rich. Adjust the carb and check the float level. Make sure there are no air leaks where the carb bolts to the manifold and that there are no leaks where the manifold bolts to the head. Make sure there is a good clean flow of fuel to the carb.

After warming the engine and following JimN's advice on setting mixture a good way to test load setting is to put it in high or road gear, hold the brakes and open the throttle. Let the clutch out until it pulls against the brakes without moving. If it does not stutter and little or no black smoke shows up then you should be set.

Dell

I forgot to say also check your air cleaner it may be clogged up and needs to be cleaned out. If its clogged it will cause the same type of problems your having

c86 delco has been replaced by c87.

karl f

Had a similar problem with my 300 Utility and Oliver 770 fouling a plug after 3-4 hours. Replaced the champion D16s with D21s. Now with all plugs being D21s, havn't had this problem for a couple of years. So try a hotter plug, especially if you use the tractor for light duty service. Al

Once I had this same problem with a 1951 Super A. All the carb adjusting in the world made no difference until I changed the float setting about 3/32" more, to lower the fuel level in the bowl just slightly. Problem solved. I know - I should not have had to do that, but that was the cure..... mike

Take out the Champions, put in Autolites or AC. Champions always cause trouble. Maybe you can find another brand, but not Champion.

(quoted from post at 14:49:22 01/16/09) Take out the Champions, put in Autolites or AC. Champions always cause trouble. Maybe you can find another brand, but not Champion.

Click to expand...

Oh, bull!

Use a hotter plug. If you have Champion D16 plugs in there, go to a D21.

Ditto on the bull!

"Champions always cause trouble. Maybe you can find another brand, but not Champion".

I think you meant....

Autolites always cause trouble. Maybe you can find another brand, but not Autolite.

(quoted from post at 13:05:15 01/17/09) "Champions always cause trouble. Maybe you can find another brand, but not Champion".

I think you meant....

Autolites always cause trouble. Maybe you can find another brand, but not Autolite.

Click to expand...

Oh, bull!