1941 Allis Chalmers B "Waving to Death" Issue

LanceLarrison · Jul 3, 2015

Hello All:

I just finished up a restoration of a 1941 Allis Chalmers B but have been rather distraught about the way it is running. Before the restoration it ran like a gem! Now, it runs great for 5 - 10 minutes before it begins to die, but then it revs back up to the speed on the throttle, then begins to die, but then it revs back up to the speed on the throttle. Each "wave" is more drastic than the previous, and eventually, after 7 or so of these "waves" it dies. I've tried pushing the throttle up when this happens, and that postpones the "waves" for a few minutes.

Yes, I have the gas on!
No, it is not choked!
Yes, the tractor has gas in its tank!

Is anyone else struggling with the same thing or have heard of something like this happening before? I have already signed this tractor up for a parade at the end of July so I need to get this fixed...sort of fast!

Thank you for any guidance you may supply in this manner!

Farmall43 · Jul 3, 2015

I know very little about Allis's but seen something similar on IH and if I remember correctly it was something to do with the governor.

jon f mn · Jul 3, 2015

Sounds like a bad coil or condenser to me. They act up when they get hot.

rrlund · Jul 3, 2015

Did you put an inline gas filter on it?

Mathias NY · Jul 3, 2015

You mentioned that you just finished a restoration. Take a look for paint around things that should not have it. I have experienced similar problems with paint around the governor and linkages. Paint could also be plugging the vent on the fuel cap.

If you had the carburetor off, there is a chance that one of the rods that connect it to the governor was not put back on with the same settings as before.

Good luck.

bjb in TX from Ne · Jul 3, 2015

Mine had a similar problem with fine rust in the tank slowly plugging up the fuel inlet. If it sat for a few moments the carb would fill back up and run some more. Finally rigged a standpipe on the inside of the tank so the majority of the rust would not plug the inlet

hd6gtom · Jul 3, 2015

Did it have an anti surge spring on the gov rod and that got misplaced in the resto?

Brent Zappe · Jul 3, 2015

I have a 1950 Allis Chalmers B over here and was restored in 1995. When I did my restoration did these three steps> ! rebuilt carburator, 2 new points & condensor in Magneto, Rotor,cap, spark plugs and wires. 3. Gasoline sedealment bowl plus a new fuel line ran away from the mainfold / heat. Want to keep the fuel away from heat this will keep it from not vapor locking up. My allis Chalmers was a basket case when bought and we took it out of a flower bed in front of a house. There was nothing there but just a frame and an engine. I am attaching some picturesof fuel line . Good luck Brent

brian(MN) · Jul 3, 2015

Doesn't sound serious to me, probably just a restricted fuel line/dirty carb to me. First check for spark after it stalls, if no spark I would check the condenser and coil, they can go bad after they heat up a little and you will have no spark. If you have good spark, check the fuel flow, starting with the sediment bowl. You need a full stream, not a drip, if it is slow, the screen could be dirty or the little outlet from the tank could be partially plugged with rust flakes. If you get a full stream to the carb, the carb could use a cleaning. You say it runs good for 5-10 minutes then starts balking, I think it is not getting enough fuel. Try opening the drain at the bottom of the carb, once the bowl is drained does it run out steady or drip? If it drips that is where the problem is.

Brent Zappe · Jul 3, 2015

The more i think about you and this promblem. I would like to say to me it sounds like the fuel is not getting to your carburator quick enough. Like a Vapor lock. The governor would make the trator die all the time because that is timing. A cracked cap or rotor or the nylon timeing teeth behind rotor would be timeing to. Coil would be messing under a load put on the tractor. To clure the promblem would be to see what your spark plugs look like. Old school Run tractor and till it dies pull plugs look and see if foul with fuel, or dry no gas. There would be your answer good luck Brent

Dick L · Jul 3, 2015

Take the gas line off at the carburetor and with the cap off the gas tank blow some compressed air back thru the tank. If that clears it up for a while it tells you where to look for the restriction. Then take the sediment bowl out of the tank and catch the gas in a can you can see and crap that could be in the tank. Disassemble the sediment bowl and clean the shut off valve. Stuff can get lodged in the sediment bowl neck also.

David G · Jul 3, 2015

It also sounds like fuel delivery issue to me, good advice on here.

colekicker · Jul 3, 2015

I would look to the needle valve in the carburetor. Everyone else has good suggestions to check also.

LanceLarrison · Jul 3, 2015

(quoted from post at 09:42:48 07/03/15) Did you put an inline gas filter on it?

There is no filter that I am aware of.

LanceLarrison · Jul 3, 2015

The carburetor was taken off. The throttle settings are the same as they were before the restoration, so I'd like to not think that the governor is the problem.

I hooked up a new choke rod, and to do so, we had to reverse the choke flap inside the air intake of the carburetor. Could this be affecting anything? It seems like it may not open as far as the previous configuration does.

Next, as I put the gas tank back on, I couldn't remember which way the sediment bowl faced before, however, I remember that the knob on it was towards the right side of the tractor and difficult to get to. The problem is that it catches on the gas tank bracket and won't turn anymore once it's about 3/4 of the way out. Could this SLIGHTLY restricted flow be an issue?

Also, I added another gasket to the gas cap and it makes it REALLY tight and secure on the tank, which I wanted so that it won't leak out when jostled around while driving as it did before the restoration. Could this tightness restrict air ventilation?

There seems to be a good spark...it runs great before it gets into the waviness.

Thanks again for your help. I hope these explanations will further diagnose our predicament.

LanceLarrison · Jul 3, 2015

I did not tinker with anything around the governer during the restoration due to the fact that it has always ran GREAT!

LanceLarrison · Jul 3, 2015

I'd also like to add to the discussion that if I wait and let it sit a minute or two the tractor will start right back up and run for another 5 - 10 minutes.

Dick L · Jul 4, 2015

Prpbly is in the sediment bowl neck. Fines build up and causes slow flow when this happens. When it sets the carburetor bowl fills up and runs until it is empty. If you blow back thru the line into the tank you would clear the restriction but would immediately start to see the fines in the bottom of the bowl as you restart the tractor. If they get by the sediment bowl from a bad screen you get this sometimes.

Dennis K (WA) · Jul 4, 2015

My guess is that your fuel tank cap is not vented. Try running it with the cap off or at least loose.
When I restored my B I bought a new gas cap and you had to drill a very small hole in it so it would vent.
Or, the hole could be plugged.
have fun at the parade.
Dennis

LanceLarrison · Jul 4, 2015

(quoted from post at 09:21:56 07/04/15) Prpbly is in the sediment bowl neck. Fines build up and causes slow flow when this happens. When it sets the carburetor bowl fills up and runs until it is empty. If you blow back thru the line into the tank you would clear the restriction but would immediately start to see the fines in the bottom of the bowl as you restart the tractor. If they get by the sediment bowl from a bad screen you get this sometimes.

<img src="http://images51.fotki.com/v1562/photos/6/34676/7862146/FilingBearings025-vi.jpg">

Thank you Dick. I probably should have cleaned the sediment bowl during the restoration or at least took it apart so I could inspect it. However, I did drain the gas and it wasn't polluted or anything.

I will take a peek at the sediment bowl soon!

THANKS!

LanceLarrison · Jul 4, 2015

Hi Dennis:

There's a small hole in it now, but I would guess that it is plugged!

I am going to take a peek at it soon!

Does your gas cap leak slightly at all?

THANKS!

Rich'sToys · Jul 4, 2015

The quickest way to check that gas cap would be to just run the tractor. As soon as it starts surging, but before it dies, reach up and take the cap off. If it straightens out, then you've found your problem. You might also feel or hear a "whoosh" as the air rushes into the tank, because if it not venting there will be a suction in the tank.
Good luck!

LanceLarrison · Jul 4, 2015

Hi Rich:

Yep! I'm going to do so soon!

Dennis K (WA) · Jul 4, 2015

Lance, no problem with cap leaks or paint damage so far.
Its been about 6 years.
Dennis

LanceLarrison · Jul 4, 2015

(quoted from post at 14:20:33 07/04/15)
Hi Rich:

Yep! I'm going to do so soon!

Hello:

Today I did some more tests on it and now its starting to have problems as it starts back up after one of these "deaths."

When it waves off and dies, it'll start right back up but then as soon as I release the clutch in the slightest bit it dies. And, if I let off the clutch really quick, it still dies. It's like it gives up and won't try again as soon as it feels pressure.

Could it be doing this if the engine isn't able to suck enough air through the carburetor? Like I said the reversal of the choke flap meant that the opening is decreased slightly.

The gas cap, in fact, is not the problem -- I drilled a small hole through the top to be sure of it.

1941 Allis Chalmers B "Waving to Death" Issue

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