Farm Equipment - Mag question

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Mag question

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=11701
Printed Date: 27 Jan 2025 at 10:55am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: Mag question

Posted By: B26240
Subject: Mag question
Date Posted: 29 Apr 2010 at 3:27pm

I have two Fairbanks Morse mags a FMJ4B and a FMX4B will both work on AC engins ? If not what is the dif? Thanks for the help. Mark L

Replies:

Posted By: wjohn
Date Posted: 29 Apr 2010 at 5:51pm

They both should work. I have a 1939 Allis Chalmers B that has an FMX4B magneto on it, which was definitely a replacement as the original magneto should have been an FMJ or FMK.

The FMJ4B is what was on most of the B's and many other Allis Chalmers tractors. I can't say for sure that the FMX was actually put on an Allis Chalmers tractor from the factory. The FMX was apparently one of the last magnetos made (and therefore the most updated) before everything switched to electronic ignition. But the FMX mag should work.

I'm no expert but this is what I have gathered from asking similar questions about my mag. Hope this helps some.

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1939 B, 1940 B, 1941 WC, 1951 WD, 1952 CA, 1956 WD-45

Posted By: Clay in MI
Date Posted: 29 Apr 2010 at 7:39pm

Internally some parts are different but as a unit they are interchangeable. I have swapped them back and forth on B's and WD's.

Posted By: B26240
Date Posted: 30 Apr 2010 at 10:39am

Thankyou wjhon and Clay for answering. Mark