[Farmall] M magneto

[WALTER AVERY]

watch for broken lockwashers that could drop into the magnet. that happened to me and it got ground up into pieces and hard to remove.
.
----- Original Message -----
From: john hall <jtchall at nc.rr.com>
To: Farmall/IHC mailing list <farmall at lists.antique-tractor.com>
Sent: Sun, 11 Jul 2010 14:49:59 -0400 (EDT)
Subject: Re: [Farmall] M magneto

The only real way to test a coil is with a coil tester and they are scarce 
as hen's teeth. Call up Standard Magneto in the morning and order a coil, 
points condensor--maybe even a rotor and cap. Ask if they have a rebuild 
kit--it maight be cheaper even if you don't use all the parts.You can buy 
all of it from them for about what a coil alone will cost elsewhere. The 
coils come out by removing a flat head screw from each end. The 
lamenations/core will have to be changed. Once you have the coil in hand, 
put one of the screws back in either tapped hole in the lamentaitons--safety 
precaution so the layers don't dislodged in the next step. Then tap the core 
out by hitting on the end that does not have the screw in it. Don't use 
something like a punch, you want something flat on the end that will cover 
as much of the lamenations as possible--don't damage that area. I generally 
press them out. A lot of time the old coil gets destroyed in this process. I 
always use my lathe to press them out. It doesn't matter which way the 
lamenations go into the new coil, if you want to keep it oriented thats 
fine. Sometimes you have to press the lamenation into the new coil. Since 
this mag doesn't have to have the magnet removed, you are in no danger of 
losing magnetism. Put the wires back where you found them and  make sure the 
coil is positioned so that the primay lead out can make good contact with 
the coil cover. You shouldn't be too far off given the way the ground strap 
on the coil is made. If for some reason you open up the front of the mag, 
pay attention to the gear timing for the rotor. There are 2 sets of timing 
marks, one for gas engines, the other for diesels. A properly serviced mag 
should give years of trouble free service if the tractor is kept under a 
shed. Dad's 47 M has the mag on it that came on it. Its been tuned up a few 
times but has never had the magnets re-charged.

By the way, if you by chance find a bunch of oil or tar like substance under 
the coil and on the armature, thats the insulating material that has leaked 
out of the coil.

John Hall

----- Original Message ----- 
From: "William Ransom" <wllmrnsm89 at gmail.com>
To: "Farmall/IHC mailing list" <farmall at lists.antique-tractor.com>
Sent: Saturday, July 10, 2010 8:11 PM
Subject: [Farmall] M magneto


>I last had the Farmall M running in 2006. When I tried to start it in 2007 
>and 2008, it seemed to be trying to start, but it wouldn't actually run. 
>Last year, I tried again to start it, and that time the engine didn't seem 
>to fire at all. Today I decided to check the magneto. When I checked it 
>before (by turning the fan by hand with the end of the coil wire close to 
>one of the clips that hold the distributor cap on), I would usually get a 
>spark, which often looked orange or white. Today, I didn't get any spark, 
>so I decided to take the magneto apart. First I measured the resistance of 
>the coil and found it was about 12k ohms (between the terminal on top of 
>the coil and the outside of the magneto). Then, I measured the resistance 
>across the points and found that it was about 1 ohm, whether the points 
>were open or closed. At first I thought maybe the condenser was the 
>problem, so I tried removing the condenser, but that didn't make any 
>difference. Then, I disconnected the coil!
>  from the points, and with the coil disconnected, the resistance across 
> the points still seemed to be about 1 ohm with the points closed, but 
> nothing conducted any electricity across the points when they were open. 
> After I disconnected it, the resistance between the red wire on the side 
> of the coil (the one that's supposed to go to the condenser and points) 
> and the outside of the magneto seemed to be about 1 ohm, so I think there 
> must be a short inside the coil that shorts across the points and 
> condenser. Do you think the coil needs to be replaced? How do you remove 
> the coil?
> _______________________________________________

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