Farmall H carb

Martin H

New User
So I've been playing around with my H a bit lately. I rebuit this tractor when i was 12 years old, bought it off my grandfather and that was 18 years ago. I don't give it a whole lot of work, and lately I have been having more leak issues etc so I decided to start doing some re-renovation stuff on it.

Anyways, my tractor has always had a little sputter which always bothered me. I know an old tractor like this with a old carb will never run like a swiss clock, but I do think I could get rid of the sputter. I cleaned the whole carb numerous times, put it back together with no luck. Still had the sputter. Now it is possible my plugs, or wires or timing or something is a hair off, but I would like to rebuild this carb totally or buy a rebuilt one.

I noticed that my idle metering jet is a little broke, what does that actually do? I think it would be a pain to get it out, since I'd probably have to snap it off and then drill it and tap it back out. Im just curious how much of a difference an idle metering jet makes and what it actually does.

The second question I have is what is that what looks to be a sheared off screw that pretty much goes in perpendicular to the air bleed valve? I did something stupid and thought it was a broken screw, so i tapped it out so that i could get in there to clean it and i ended up breaking the tap in there, and i made a mess getting it out. What is that there? You can see it on the side of your carb, its like a little brass piece thats flush with the lower carb wall. I cant find any information about it or any part numbers for it. I probably shouldn't have drilled it out, but its too late for that. Does anyone know what this is? Any recommendation on rebuilding your own or buying a rebuild? Ill try to find a picture of the thing I'm talking about. Thanks guys
 
here is a picture. I put the area in red. What is that brass threaded pin for? does that come out to remove the air bleed? I drilled it out and i don"t think i was supposed to.
a145958.jpg
 
Reading between the lines it appears you have limited knowledge of carburetion functions, and no manual. You are flying blind so to speak.
Google "rebuilding Farmall h carburetor, for instructions, manuals , videos. Don't touch that carb again until you can at least identify the parts and know what their function is.
The idle mixture screw varies the fuel air ratio at minimum throttle setting. If your H was "sputtering " at WOT the idle jet had nothing to do with it. "Sputtering sounds more like an ignition issue. "Coughing" or "belching" are associated with the carb.
Did you adjust the valves as outlined in a manual?
 
I actually have a fair bit of knowledge with carbs, just not too much with this particular one. You are right I should have researched some more. Its actually more of a coughing thing, I didn"t know how to explain it. At wot it just coughs a tiny bit. I"ve done a fair bit of research, its just i called case ih today and they want 175 dollars for the rebuild kit which is a lot of money. Its almost worth it for me to just buy a rebuilt one, especially since i buggered up the first one. I really just wanna know what that brass pin is lol.
 
That brass part you have circled is a plug. Not a service item as it is used to plug one of the internal passages during the manufacturing of the carburetor. When you say sputtering, I guess you mean it spits and sputters when you go from low engine speed to high speed. What we term as cold blooded. Pretty hard to cure completely and if you did the engine would probably run pretty rich after it got up to speed. Far as idle jet, the actual jet is quite a ways down inside of the long jet so if the screwdriver slot is damaged it most likely still does not affect the jet. Broke a few off in my day. Have a tap to restore threads as needed. Also, never heard of a good rebuild kit for an H. I always buy the parts I want separately. Lot are no longer available.
 
Think that's where a passage was drilled in the carburetor and then plugged on the outside. Plug should stay there.
If just one side of the idle jet ears made for a screwdriver to fit is broke it will work okay if the hole in it is open. Around a .022 or .023 hole. If broke off even with the casting it needs replaced.
About the flutter, do you have a magneto or distributor ignition?
Notice Pete already gave you a answer while I was typing.
 
Here"s my H carb adjusting procedure, put together by combining 3 or 4 different manuals;
Make sure the float isn’t sticking or touching the insides of the float chamber. Some previous advice was to use a Dremel tool and smooth the insides of the float chamber so it doesn’t rub or touch. Pretty important. Set the float so the top of it rests 1 27/32" above the flat surface of the float chamber.
Initial settings are as follows to get it started;
Main fuel adjusting screw, big screw facing down at an angle, towards the rear, at the bottom of the carb; 2 1/2 to 3 turns open. This main screw turns clock-wise for leaner mixture. [This screw adjusts fuel.]
Idle air-mixture screw, smaller screw facing forwards, on upper left-hand side of carb; 1 to 1 1/2 turns open. This idle screw turns counter-clockwise for leaner. [This screw adjusts air.]
Idle speed screw, faces outboard, at the top of the carb; set for 450 rpm, and make sure the governor correctly engages the slot. [This screw adjusts RPM’s.]
Final settings are determined as follows;
Get the engine warmed up, and idling.
Turn OUT the idle air-mixture screw until rough running, then turn in until it idles smooth. (Mine is set at 1 turn open.)
Rev it up, wide open, warmed up, then turn the main fuel adjusting screw IN until rough, then out til smooth, then 1/4 turn to 1/2 turn further out. (Mine is set at 1 turn open. Other advice has been to set it at 2 1/2 turns open for pulling implements.)
Should rev up smoothly and evenly.
Too Lean = stumble, sputter, damaged melted plugs.
Correct = tan plugs.
Too Rich = back smoke, black sooty plugs.
 
Thanks for the info and for answering my questions. Ill play around with it later. The idle metering jet isn't broken, just the screwdriver tabs and the hole appears to be clear. Thanks again
 
Thanks for some of the explanation. I have a magneto on my tractor. Ya i was going to check the timing and make sure everything is lubricated and working well.
 

That sputtering is more than likely being caused by worn out bushings, advance mechanism, etc. in the distributor. It is also highly possible that the ignition timing is too far advanced.

Having said all that, I can also tell you that even with everything being absolutely perfect, there will still be an occasional miss or sputter at idle.
 
Ok thats what I was curious about. I was pretty much at that point, i just feel i could get it running just a little better. And what about when you rev it up? there isn't instantaneous power right away is there? Mine had just a little bit of lag if you reved it up fast.
 

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