Timing WD Magneto
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=201107
Printed Date: 28 Nov 2024 at 4:48am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Timing WD Magneto
Posted By: ForgivenCreation
Subject: Timing WD Magneto
Date Posted: 29 Apr 2024 at 1:39pm
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So I am getting a backfire through the carb while running the tractor at any speed. I did the initial timing setup but I feel it it off causing running issues, it also cranks forever before starting and is very difficult to keep running. I have fully cleaned the carb twice. Adjusted valve lash to 15 thou cold and then warm. The manifold is in awful shape but I would prefer if that was last to fix as its not cheap. I have new plug wires ready to order as the magneto someone put on looks to be from a Caterpillar, yellow paint and a metal 90 degree cap cover deal. I set initial timing with the mark on the bottom through the viewing plate. The mag is basically in the center of its adjustment. What rotation does what? I have a timing light and all, do I really have to climb under the tractor to read timing while it's running.... Feels real unsafe so I want to vet how first.
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Replies:
Posted By: steve(ill)
Date Posted: 29 Apr 2024 at 1:52pm
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there should be two marks.. a FIRE mark and a TDC Top Dead Center mark.... THe STATIC timing is to set the mag to CLICK the impulse when the Crank is at the TDC mark... If you are too far off, it will not start or very hard to start... Mags have an ADVANCE built into the impulse.. Most AC units are 30 degrees.( that is the FIRE MARK once the tractor is running).... Some companies use a 20 or 25 degree advance.. If you have the WRONG MAG for the tractor, that can be a problem.. Also the motor fires 1-2-4-3 with #1 at the radiator.. Make sure you dont have a couple wires switched.
------------- Like them all, but love the "B"s. |
Posted By: Alberta Phil
Date Posted: 29 Apr 2024 at 2:07pm
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If, as you say, the manifold is in terrible shape, there is a good chance you have vacuum leaks and it is sucking in fresh air which will lean out the mixture and cause those symptoms that you stated, including the hard starting. |
Posted By: steve(ill)
Date Posted: 29 Apr 2024 at 4:50pm
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what is the TAG number on the side of the MAG ?? ------------- Like them all, but love the "B"s. |
Posted By: SteveM C/IL
Date Posted: 29 Apr 2024 at 7:29pm
| Be sure you know direction rotor turns when wiring plugs. |
Posted By: ForgivenCreation
Date Posted: 29 Apr 2024 at 9:46pm
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Here are some pictures of it. Someone many moons ago broke the ear off the top of the mag. The plug ends shown are screw in and have resistance built in somehow.   
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Posted By: steve(ill)
Date Posted: 29 Apr 2024 at 10:06pm
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The FMJ-4B3 is a very common mag for the Allis Tractors... The box on the end with the plug wires is NOT common. I have heard there were a couple variations for "extreme duty" ... but have not seen one like that.... Rotor on the FMJ is horizontal.. how they got the wires out the TOP is odd... ------------- Like them all, but love the "B"s. |
Posted By: SteveM C/IL
Date Posted: 29 Apr 2024 at 10:51pm
| think I'd be looking for a different mag.... |
Posted By: IBWD MIke
Date Posted: 30 Apr 2024 at 8:16am
I'd find a distributor!
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SteveM C/IL wrote:Posted By: steve(ill)
Date Posted: 30 Apr 2024 at 8:26am
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I think this is the Frankenstine Tractor... Something like Johnnie Cash 58 Caddy.... He has a MODIFIED FMJ mag , a 1962 FORD 3 post Generator and a 1977 F250 voltage regulator... All he needs now is the seat off a John Deere 2 banger..  ------------- Like them all, but love the "B"s. |
Posted By: IBWD MIke
Date Posted: 30 Apr 2024 at 8:35am
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