1939 Allis B carb float adjustment not enough or to much gas

Shealray · Jul 12, 2017

I Rebuilt zenith carb. Everything clean. Having issue with getting float correct. Ran Allis have these symptoms after rebuild.

No choke
Air mixture needle all the way in.
Tractor runs fair but still not right smooth.

Air mixture needle out gets worse (sputters) as you turn it out more.

Am I getting to much gas? Am I not getting enough gas?
I know measurement of float bottom to top face of carb is
suppose to be 1 5/32. My floats are about level with face.
If to much gas should measurement be more or less then 1 5/32?

Thanks for the assistance it is very much appreciated.

bjb in TX from Ne · Jul 12, 2017

The float adjustment does not really affect how much gas flows through the carbureator. If it is incorrectly adjusted, the fuel level will be too high and spill out the nozzle and drip out the sintered bronze drain under the
choke plate.

1. Does it have a power jet adjustment at the base of the carb? If so, both should be initially set for 1 and 1/2 turn out.
2. When you rebuilt it did you make sure all three jets were clear? One is the main jet at the base of the bowl, there is a vent meter on upper half of the mating surface and I think a third one in the top of the lower half
depending on the model.
3. What is the throttle linkage to the governor doing? Do you have the throttle spring in place on the linkage?

Do you have a picture of the carb installed to help troubleshoot?

My 1940 B like an extra 1/4 turn out on the power needle for a cold start when hand cranking.

rustyfarmall · Jul 12, 2017

(quoted from post at 07:51:37 07/12/17) I Rebuilt zenith carb. Everything clean. Having issue with getting float correct. Ran Allis have these symptoms after rebuild.

No choke
Air mixture needle all the way in.
Tractor runs fair but still not right smooth.

Air mixture needle out gets worse (sputters) as you turn it out more.

Am I getting to much gas? Am I not getting enough gas?
I know measurement of float bottom to top face of carb is
suppose to be 1 5/32. My floats are about level with face.
If to much gas should measurement be more or less then 1 5/32?

Thanks for the assistance it is very much appreciated.

You missed some dirt/crud somewhere.

old · Jul 12, 2017

If it only has the one adjustment which is towards the top of the carb that is the idle adjustment and out is leaner and in is richer. Good chance you missed something in the main jet passage way area. When you cleaned the carb did you use a small wire or as I do a torch tip cleaner tool and poke out all the passageways. If the carb is like the one on the C I have it has no main jet adjustment so if you miss something ti will not run like ti should

Shealray · Jul 12, 2017

(quoted from post at 08:34:25 07/12/17) If it only has the one adjustment which is towards the top of the carb that is the idle adjustment and out is leaner and in is richer. Good chance you missed something in the main jet passage way area. When you cleaned the carb did you use a small wire or as I do a torch tip cleaner tool and poke out all the passageways. If the carb is like the one on the C I have it has no main jet adjustment so if you miss something ti will not run like ti should

All jets clear. Only one adjustment up top. Idel adjustment in all the way richer then this tells me not enough gas. Float has to be adjusted for more gas? Thinking float set a little above level for more gas CORRECT?

Shealray · Jul 12, 2017

Shealray · Jul 12, 2017

Since idel is all the way in not enough gas. How do I get more gas?

bjb in TX from Ne · Jul 12, 2017

Since it sputters when you move the idle out, and you think it is a gas supply problem do the following:

1. Set the idle to 1-1/2 turns out from bottom (beginning default setting)
2. Start it with the choke on. It should run
3. Try taking the choke off; if the tractor dies, you are correct it is not getting enough gas. The main jet passage is plugged.
4. Remove the nut that you have at the lower left side of the bowl. Deep in that passage is the main jet. It needs to be cleaned (just soaking a carb will not free this passage).

(the reason this works is the choke circuit bypasses the main jet and adds fuel at a different place in the bore of the carb. Every time I have had a motor that will only run on choke, and die wide open was due to a
plugged main jet)

Like old said you need a long torch tip cleaner or I use thin plastic string trimmer. The jet is removable, but that is better done off the tractor with a screwdriver custom ground to the width (it is brass and easily damaged
with the wrong screwdriver).

If you take if off again, try blowing compressed air through each hole of both haves. You should be able to feel a good stream of air from each passage way. If it feel restricted clean the carb again.

Shealray · Jul 12, 2017

(quoted from post at 11:22:48 07/12/17) Since it sputters when you move the idle out, and you think it is a gas supply problem do the following:

1. Set the idle to 1-1/2 turns out from bottom (beginning default setting)
2. Start it with the choke on. It should run
3. Try taking the choke off; if the tractor dies, you are correct it is not getting enough gas. The main jet passage is plugged.
4. Remove the nut that you have at the lower left side of the bowl. Deep in that passage is the main jet. It needs to be cleaned (just soaking a carb will not free this passage

(the reason this works is the choke circuit bypasses the main jet and adds fuel at a different place in the bore of the carb. Every time I have had a motor that will only run on choke, and die wide open was due to a
plugged main jet)

Like old said you need a long torch tip cleaner or I use thin plastic string trimmer. The jet is removable, but that is better done off the tractor with a screwdriver custom ground to the width (it is brass and easily damaged
with the wrong screwdriver).

If you take if off again, try blowing compressed air through each hole of both haves. You should be able to feel a good stream of air from each passage way. If it feel restricted clean the carb again.

Super will do later today. Thank you

Steve@Advance · Jul 12, 2017

The float level will have some effect on the mixture, but very minimal (as long as it's not flooding).

Check the gasket and mating surfaces where the bowl meets the upper housing. There is a small hole where the idle fuel gets drawn up from the main well. If the housing is warped, the venturi is not seated completely, the gasket is torn or made wrong, that passage will not seal completely and cause lean idle.

Also check for vacuum leaks.

How's the ignition timing, points, plugs, etc?

Have the valves been set lately?

rustyfarmall · Jul 12, 2017

(quoted from post at 07:51:37 07/12/17) I Rebuilt zenith carb. Everything clean. Having issue with getting float correct. Ran Allis have these symptoms after rebuild.

No choke
Air mixture needle all the way in.
Tractor runs fair but still not right smooth.

Air mixture needle out gets worse (sputters) as you turn it out more.

Am I getting to much gas? Am I not getting enough gas?
I know measurement of float bottom to top face of carb is
suppose to be 1 5/32. My floats are about level with face.
If to much gas should measurement be more or less then 1 5/32?

Thanks for the assistance it is very much appreciated.

The float needs to be set exactly per manufacturer specifications. The engineers spent a lot of time determining the ideal float height. Attempting to outguess them is a waste of time. Carburetors are precise and intricate. If you attempt a rebuild, take the time to study and understand just how it all works.

Steve@Advance · Jul 12, 2017

Does that have a one piece intake/exhaust?

If so, they can burn through internally, start putting exhaust into the intake.

old · Jul 12, 2017

The main jet has a plug cover sort of thing. Pull it off and turn on the gas. You should get a good steady flow of gas out of it when you do that. If you do not get a steady flow then it is clogged up simple as that. Idle jet should be adjusted to about 1.5 turns out form bottom and then left there.
Can you pull the carb drain plug and fill a pint jar in under 3 minutes??

Shealray · Jul 12, 2017

(quoted from post at 12:58:56 07/12/17) Does that have a one piece intake/exhaust?

If so, they can burn through internally, start putting exhaust into the intake.

One piece intake.

Shealray · Jul 12, 2017

Fill one pint jar in 2 minutes.

Shealray · Jul 12, 2017

Gaskets new, timing, pulgs good. Flooding.

Factory specs say 1 5/32" from surface of carb. Took carb to factory rep, tractor place dealing with allis. Float was set a lot more then 1 5/32 it flooded. They did not charge me, but not sure why it was set this way. So I am doing this my self.

old · Jul 12, 2017

If I remember right you have my phone number call me if it would help.
You might try with the air cleaner off fire it up and place your hand over the air intake and try to do so in such a way as not to kill the engine. You should both get a good suction and also gas on your hand. Doing so may even help fix the problem because some times that is enough to pull some junk out of the main jet which is where your problem is likely to be

Shealray · Jul 12, 2017

(quoted from post at 15:43:22 07/12/17) If I remember right you have my phone number call me if it would help.
You might try with the air cleaner off fire it up and place your hand over the air intake and try to do so in such a way as not to kill the engine. You should both get a good suction and also gas on your hand. Doing so may even help fix the problem because some times that is enough to pull some junk out of the main jet which is where your problem is likely to be

going to take carb apart clean main jet get dirt out. How do i get dirt out?

old · Jul 12, 2017

The main jet is the one with the cover plug. Remove that plug while on the tractor and turn on the gas and let it flow. If it does not flow well use a small wire or as I do a torch tip cleaner tool and poke it out while the gas flows which will loosen up the rust/dirt and the gas will flush it out

Shealray · Jul 13, 2017

(quoted from post at 15:43:22 07/12/17) If I remember right you have my phone number call me if it would help.
You might try with the air cleaner off fire it up and place your hand over the air intake and try to do so in such a way as not to kill the engine. You should both get a good suction and also gas on your hand. Doing so may even help fix the problem because some times that is enough to pull some junk out of the main jet which is where your problem is likely to be

sorry lost your number. Email. [email protected]

old · Jul 13, 2017

My e-mail is always open on Y-T so it should be easy for you to send me an e-mail Just click on send e-mail in the bottom of the box if your on classic or if on modern just click on my name and it should pull up an option to e-mail me

Shealray · Jul 13, 2017

(quoted from post at 09:47:29 07/13/17) My e-mail is always open on Y-T so it should be easy for you to send me an e-mail Just click on send e-mail in the bottom of the box if your on classic or if on modern just click on my name and it should pull up an option to e-mail me

orry no link to send email. Mine is [email protected]

rustred · Jul 13, 2017

first of all... was the carb soaked in carb cleaner for at least one hr? then washed in cool water, then blow out all passages with air.everybody seams to have a different way to do a carburator. but the cleaning is by far the most important.float level slightly off will not have much impact on running. turn carb upside down with float resting on needle and if float sits level its good. just as the saying goes... float level.

Shealray · Jul 13, 2017

(quoted from post at 20:04:03 07/13/17) first of all... was the carb soaked in carb cleaner for at least one hr? then washed in cool water, then blow out all passages with air.everybody seams to have a different way to do a carburator. but the cleaning is by far the most important.float level slightly off will not have much impact on running. turn carb upside down with float resting on needle and if float sits level its good. just as the saying goes... float level.

Did float hanging away from pin. Will try what you suggest.

1939 Allis B carb float adjustment not enough or to much gas

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