B mag timing
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=185512
Printed Date: 25 Oct 2025 at 3:52pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: B mag timing
Posted By: ihscout
Subject: B mag timing
Date Posted: 03 Jan 2022 at 12:19am
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I'm still having issues with timing my mag. I've replaced the 40° impulse coupler with a 30° one and it runs much better but still not right. What would cause the rotor to be so far off the timing lug when "fire" is as pictured?  ------------- '40 AC B - My Pappy always told me "Use your head for something other than a tack hammer!" I did. It makes a great 16 pound sledge hammer. |
Replies:
Posted By: steve(ill)
Date Posted: 03 Jan 2022 at 2:16pm
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You want the MAG to line up with the TOP DEAD CENTER mark on the crank.. That is where it STARTS... Once running, the spring loaded weights fly out and rotate the internals so you will be it to fire at the FIRE mark or 30 degrees... ------------- Like them all, but love the "B"s. |
Posted By: steve(ill)
Date Posted: 03 Jan 2022 at 2:19pm
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WIth the motor at TDC and the mag installed, you should see the rotor point to #1 ( actually you will hear the coupler "SNAP" as you rotate to TDC.. If it is off the TDC mark when you hear the SNAP, then loosen the two mounting bolts on the mag and rotate toward or away from the engine till you get it right... Your really listening for the SNAP... and not exactly where the rotor is pointed.. It will be CLOSE, but not exact until the SNAP. ------------- Like them all, but love the "B"s. |
Posted By: Eric B
Date Posted: 03 Jan 2022 at 3:37pm
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Your internal gears may be off by one tooth. As Steve is mentioning the "snap" going off... I have always found by observing the rotor at the snap, the tab of the rotor covers half of the far side of the terminal to plug wire #1. I have had some mags where the markings to match the gears at the back are extremely faint or not visible at all. The only way to find the correct gear mesh is by studying very closely when the point begin to open. I always confirm by looking at the rotor position at the snap as I described above. It has worked every time. ------------- Currently- WD,WC,3WF's,2 D14's B. Previously- I 600,TL745,200,FL9,FR12,H3,816 LBH. Earth has no sorrow that Heaven cannot heal! |