Farm Equipment - Allis C jumps time

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Allis C jumps time

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=13911
Printed Date: 02 Feb 2025 at 4:41am
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Topic: Allis C jumps time

Posted By: Craig Reavley
Subject: Allis C jumps time
Date Posted: 15 Jun 2010 at 9:02am

About once a year my 1949 C will jump time and start backfiring, and wont start. I changed the condensor, and it is still backfiring. It ran perfectone minute, and the next time I went to start it it acted liked it fired, and spun the engine backwards, now with a new cndensor all it does is backfire, louder tyhan a shotgun through the muffler

Replies:

Posted By: Dakota Dave
Date Posted: 15 Jun 2010 at 10:00am

Every thing in you timing is gear driven If you havr jumped timing you got problems.

Posted By: Dick L
Date Posted: 15 Jun 2010 at 10:07am

It is all gear driven so it can not (jump) time without gear teeth being stripped. So if you have checked for TDC on the compression stroke for number one cylinder and it did not just fire number one spark plug you need to check all the timing gears for missing or stripped teeth, starting in the magneto all the way back to the crankshaft.

Posted By: Jeff Z. NY
Date Posted: 15 Jun 2010 at 10:07am

Replace the points.
Make sure the strip on the points that rides on the cam is not worn down and make sure the points are gapped correct.
Turn the engine over by hand so the points are on the high spot on the lobe and see what the gap is when the engine is acting up.
If the points are not opening you will get a weak yellow spark and the engine will be out of time and will not run well if it runs at all.

Also make sure the magneto or distributor is bolted down tight.

Posted By: Craig Reavley
Date Posted: 15 Jun 2010 at 10:27am

I cant imagine I have a broken gear. I went through this motor completely, and everything looked good a few years back.I'll recheck the timing tonight and see what could have changed. I will check the points even though they are a year old. It has a distributor instead of a mag.

Posted By: Jeff Z. NY
Date Posted: 15 Jun 2010 at 10:48am

Craig, Last year I was out mowing with the B and it was running well.
I parked it and the next time I went to run it would not start.
Backfired alot.
The tab on the points that rides the cam was almost gone.
Points were not opening.
Changed the points and it ran like new.
How it ran just before that is beyond me.
Stranger things have happened I guess.

Posted By: Crowman17
Date Posted: 15 Jun 2010 at 12:16pm

I had a simular problem with my C and it was the teeth on the fiber gear for the roter were getting stripped caused simular problems.

Marc

Posted By: Brian Jasper co. Ia
Date Posted: 15 Jun 2010 at 1:04pm

I would look the distributor cap over very closely. The dist drive gears would have to be really worn to jump over each other. Can't imagine the cam gears jumping either. Sounds to me like you have a secondary crossfire problem. Look for a crack from the coil post to one of the others or ignition wires cross firing.

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