FMJ Mag Help
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=165543
Printed Date: 07 Apr 2026 at 6:55am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: FMJ Mag Help
Posted By: AaronSEIA
Subject: FMJ Mag Help
Date Posted: 04 Nov 2019 at 4:02pm
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Working on getting my WC back running and have hit a snag. Mags are magic as far as I'm concerned and I need some help. Should I have continuity across the points when closed? I don't know
if it's my multi tester or what, but I'm not getting any. Plug wires show infinite ohms which would mean open circuit. I get about 4800 ohms resistance
between the condenser side wire of the coil and the center lug. About
1.2 ohms between the 2 wires of the coil. Can't seem to test the
condenser with a digital multi tester. Short of sending this thing to
someone and spending a lot of money, what's the best course of action?
Point/condenser and plugs/wires? Coil seems to test OK I think. Not a lot of run time on the mag, but it's been 20 years since it went together. AaronSEIA
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Replies:
Posted By: Gerald J.
Date Posted: 04 Nov 2019 at 5:04pm
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Sounds like there are several wires disconnected in the magneto. The resistance at the points should be the primary coil resistance with the points open and zero with the points closed. Might be a sign that the points need a thorough cleaning. I have a shop manual for FMJ at: http://geraldj.networkiowa.com/Trees/FM-Xmagneto.pdf" rel="nofollow - http://geraldj.networkiowa.com/Trees/FM-Xmagneto.pdf Might not be the perfect match to your magneto but the findamentals should be similar. Gerald J. |
Posted By: Steve in NJ
Date Posted: 04 Nov 2019 at 5:34pm
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Take some TV tuner cleaner or Brakekleen and give a spritz to the points and run a rag through the contacts. Do this a couple times. Sounds like there's ozone or a film or corrosion on the contacts. Don't use a file, cause all that will do is remove the cadium plating from the contacts. The Cadium helps keep corrosion down. When they sit for a long time, they'll get a film on them and boom, no spark...... Steve@B&B ------------- 39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife |
Posted By: Dave Richards (WV)
Date Posted: 05 Nov 2019 at 8:41am
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You are showing your age Obiwan. Do they still call it tuner cleaner in your area or do you just have a very old can? Sorry, no pun intended.  |
Posted By: chaskaduo
Date Posted: 05 Nov 2019 at 8:57am
How about Variable Pot, say that and you'll have every millennials attention within ear shot.  ------------- 1938 B, 79 Dynamark 11/36 6spd, 95 Weed-Eater 16hp, 2010 Bolens 14hp |
Posted By: CTuckerNWIL
Date Posted: 06 Nov 2019 at 9:37pm
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An old timer told me once, he used a dollar bill to drag thru the points. Said there was enough dirt and grit built up on an older bill to polish them just enough. Then drag a piece of white paper thru to clean up any leftovers. With a digital meter, check ohms, then switch to voltage. The ohm meter should charge the condenser and when you check voltage, it should slowly drop off. ------------- http://www.ae-ta.com" rel="nofollow - http://www.ae-ta.com Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF |
Posted By: Steve in NJ
Date Posted: 07 Nov 2019 at 1:14pm
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Guess I'm showin' ma' age Dave. They don't make TV tuner cleaner anymore?.....Still have a can of that on the shelf. Still works! LOL!! Steve@B&B ------------- 39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife |
Posted By: chaskaduo
Date Posted: 07 Nov 2019 at 1:20pm
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Charlie when you say, "With a digital meter, check ohms", where are you using the test leads, and are the points open or closed? ------------- 1938 B, 79 Dynamark 11/36 6spd, 95 Weed-Eater 16hp, 2010 Bolens 14hp |