M carb ?

sammydwm · Sep 12, 2016

Have an old M that I'm trying to get running properly.
Carb is leaking gas when the shutoff is open on the tank.
The tractor runs but acts like it is rich. And there is lots of condensation above the carb.
Would like to rebuild the carb but there are 2 kits at the store and no tag on my carb at all. Is there a way to figure out which carb I have?
Also there is a hole in the bottom of the thing open to the atmosphere, is that normal or is something missing? It is in the area where the venturi is not, where the float is.

old · Sep 12, 2016

Take your carb to say an O'Reilly's auto parts store and they should be able to match it up to one of there kits. As for that hole are you saying it is in the float bowl area?? If yes does it leak out of it when the gas is turned on. Sounds like the carb drain plug is missing and if it is there is no way I think it could run. Now if the hole is in the air intake tube area that should have a brass screen in it and it is there to leak off gas if it is flooded.

As for it leaking gas your float could be bad or you could have some junk in the needle seat which is not letting the float stop the flow of gas which will make it run to rich

FBH44 · Sep 12, 2016

I will say this, I rebuilt the carb on my H and had absolutely no idea what I was doing... but it was simple, and the old girl ran just fine afterward. Go for it.

D Slater · Sep 13, 2016

Using a basic kit without a discharge jet or butterfly shaft, don't think it will matter on a kit. With a discharge jet I don't know if the aftermarket is furnishing different ones for gasoline or kerosene or distillate carburetor. Other things to consider is early tractors used a different butterfly shaft than most. Some carburetors and kits have a one screw choke butterfly and shaft compared to 2 screw ones. If the carburetor has jetting for fire crater piston kits reuse because no aftermarket kit will be like those.
Drip hole in bowl bottom had filter packing and a small expansion plug with small hole to hold filter material in.
Does the bowl or throttle body have a casting number on them. 4 numbers followed by letter or two letters? Make sure carburetor doesn't have a round ID tag about 5/16 or 3/8 inch in diameter near where the throttle tube attaches to carburetor. Some replacement throttle body castings or all didn't have a ID tag because the same throttle body was used on different number carburetors. ID tag could be damaged or lost also if not there.

Goose · Sep 14, 2016

I've found you basically eliminate overflow problems in H's and M's by setting the float 1/8" lower than the book says.

M carb ?

sammydwm

Member

old

Well-known Member

FBH44

Well-known Member

D Slater

Well-known Member

Goose

Well-known Member

Similar threads