Farm Equipment - B-Allis Chalmers

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B-Allis Chalmers

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=93689
Printed Date: 08 Sep 2025 at 12:45pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: B-Allis Chalmers

Posted By: Nat
Subject: B-Allis Chalmers
Date Posted: 12 Aug 2014 at 2:29pm

I bought my son a CA and my son in law a B a couple years ago. the CA still runs like a champ but the B has never ran like it should. The motor has great compression, and is timed correctly. I replaced the points, condenser, coil and rebuilt the carb. the only thing that helped was the carb but now it's doing it again. It will start and run pretty good but sounds somewhat loke it's loaded with fuel. If the idle scwer is set at 1 3/4 turns out it sounds like its flooding but if you run it all the way in it sounds good. It will sit there and idle or you can through the throttle wide open and it still runs good but if you get on it and move around it will cut off. It will restart in a minute and do the same all over but you can leave it sitting with the throttle wide open it will run all day. What have I overlooked or am I missing something? thanks. Nat

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Nat

Replies:

Posted By: Dick L
Date Posted: 12 Aug 2014 at 3:06pm

For this discussion the carburetor has two circuits. The idle circuit and the power circuit. The adjustment at the top is the air adjustment for (idle) Most B's do not have an adjustment for the power. The factory determined the size orifice needed for full power for the way the engine was built.
The idle rpm is actually set with the stop screw on the backside of the carburetor. The idle adjustment screw is to mix the correct amount of air into the fuel to make the engine run smooth where the stop screw is set. To get the smooth running at idle both the stop screw and air adjustment screw will need to turned a small amount each until you have the desired rpm's.

When you are running wide open you are not in the idle circuit. You can at that point remove the idle screw and it will still run fine. If you can not get the idle adjusted you may have dirt in the idle circuit blocking fuel or air. Could even be a gasket covering a hole.

Posted By: Nat
Date Posted: 12 Aug 2014 at 5:05pm

I took the carb back apart and cleaned it really good and for 20 minutes it ran as nice as new. someone has removed the setteling bowl and replaced it with one that doesnt have a shut off. they then put a plastic cut off valve in line so I'm thinking that is the problem. maybe not letting enough fuel to keep the bowl full makeing it run fine sitting but sputter and stop when moving. Does that make sense to anyone?

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Nat

Posted By: Dick L
Date Posted: 12 Aug 2014 at 8:02pm

The first thing I would do at this point would be to take the plug out of the bottom of the carburetor and see how long you get a good flow of fuel out of the bottom of the carburetor. If not solve that problem by what ever means it takes. New sediment bowel? New fuel line? Just make sure you have a good flow.
I would venture a guess that you are dealing with more than one problem. When you are running wide open and it does not have enough power to move the tractor in low gear you might want to check timing.

If a good fuel flow solves you problem your done but if it doesn't timing would be the next place I would check. Tackle one thing at a time.

Posted By: Dean (West MI)
Date Posted: 12 Aug 2014 at 9:07pm

Why not take the carb off the CA and put it on the B and see how it runs? If it runs good, then you know the problem is in the B carb. If it doesn't run right, then start on other things.

Process of elimination, start with the known variable and work from there.