Setting carb on M

Baelee05 · Mar 17, 2011

Well I finally got the M wired up and got my governor problem solved. Now I am having some trouble getting it to throttle up smoothly. I rebuilt the carb so maybe I don't have something set correctly. I was told to turn the idle screw while at idle until it starts to sputter and then back it off a half turn. Same procedure with the main screw at full throttle. The idle screw I had turned in tight and it didn't pulled down and the main screw at full throttle was almost all the way in before it started to stumble. It runs real nice at idle and once it stutters and stammers it's way through it runs good wide open. It is a magneto system with brand new 3116 autolite plugs and plug wires. Any suggestions? Thanks guys.

old · Mar 17, 2011

Sounds like you got a cheap carb kit with poor if any instructions. Me I set the idle screw at 1.5 turns out from bottom and leave it at that. Now the main jet that is a different story. On the Farmall tractors I start at about 4-5 turns out then with it running about 3/4 throttle open it up till you just start to get black smoke then turn it back in till the smoke stops. Or you can also do the power test way and adjust it for max pulling when working it

rustyfarmall · Mar 17, 2011

(quoted from post at 15:40:22 03/17/11) Sounds like you got a cheap carb kit with poor if any instructions. Me I set the idle screw at 1.5 turns out from bottom and leave it at that. Now the main jet that is a different story. On the Farmall tractors I start at about 4-5 turns out then with it running about 3/4 throttle open it up till you just start to get black smoke then turn it back in till the smoke stops. Or you can also do the power test way and adjust it for max pulling when working it

Low speed idle (air) is 1 1/2 turns out. Leave it right there until the engine is fully warmed up. Then, and only then, you MIGHT need to turn that screw in OR out, but 1/2 to 3/4 of a turn in either direction should be sufficient. If it is NOT, it's time to take the carburetor apart again 'cause you missed something.

The high speed idle, or load adjustment screw is set at 3 turns out. Period. Leave it there. Adjustment is required ONLY, and I repeat ONLY, if the engine stumbles under FULL LOAD. Not just at wide open throttle, but at FULL LOAD.

Every M or H that I have ever been around always made full horsepower and performed very well with the load screw set at just 3 turns out.

John M · Mar 17, 2011

Pretty much the same way I do it RF, except I look at the smoke coming out of the pipe at idle. Each tractor and its carb are different from the one next to it and each have their own quirks, so I start at 1 - 1 1/2 and adjust slowly until the smoke clears. Main is usually 3 turns out out my show tractors, but my working M gets 4.

pete 23 · Mar 17, 2011

Set the idle screw where it idles the best and accelerates the best. May be a compromise. No set amount of turns but it is ordinarily in the one to two turns. If you cannot get it to load up or nearly kill you have an imbalance in the jetting. Probably the idle jet or a leaky bowl gasket or too high or low fuel level. Also , has to be soaked to get perfectly clean .

Baelee05 · Mar 17, 2011

Thanks guys. I meant to say one and a half turns on each. That is what an independent shop told me. I'll set it as per the instructions you guys have given me. I'm thinking something isn't right inside the carb. I'm just not sure what.

Setting carb on M

Baelee05

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old

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rustyfarmall

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John M

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pete 23

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Baelee05

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