[Farmall] More Magneto Woes

[John Hall]

 Ben, assuming your impulse is working properly, hook a plug up to the wire 
coming out of the coil cover. If it fires there then your problem is in the 
short wire that connects the cover to the distributor cap, the cap itself, 
or the rotor button. I you don't have fire there, pull the coil cover and 
lay a screw driver about a 1/8" above the lead-out on the coil to see if you 
have fire there--careful you don't touch the blade! If not, start looking 
for anything touching the frame that is not supposed to. Possibly you left 
something loose and it has gotten against the frame and is grounding it out. 
I would pay special attention to where the kill switch terminal goes through 
the frame. Re-check your point gap and make sure they are clean, even if 
they are new. If all else fails, unhook the coil and condenser,  grab your 
voltmeter and start checking for anything that is grounded and not supposed 
to be.

 Also, when you are testing a mag, if it fires a spark plug set to the 
proper gap, that is no indication it is hot enough to run an engine. Rule of 
thumb is it must fire a 1/4" gap, minimum. I have rebuilt mags that would go 
7/16". Take and old plug and bend the grounding part of the electrode to get 
a really big gap. Magneto rebuilders have an attachment that allows them to 
vary the spark gap on each output of the cap.

As for your question about the condenser, rule of thumb is change it every 
time you change the points, unless you are working on some really oddball 
mag that condensers are hard to find or a pain to change. The IH dealer dad 
worked for refused to stock individual points and condensers, they only sold 
them in sets.

Also, the only way you can screw up the coil is to hook up a wire from the 
battery. I've seen it more than once and it ain't pretty--smells bad too. A 
lot of folks just don't get it that a mag works without a battery. I gave up 
arguing with a fellow one day that a weak battery wouldn't make his mag not 
work.

One other thought comes to mind, when you pulled the old coil out, was it 
really oily and did it appear to have leaked all over the inside of the 
mag.?

John Hall

----- Original Message ----- 
From: "Ben Wagner" <ben at olde-books.com>
To: <at at lists.antique-tractor.com>; "'Farmall/IHC mailing list'" 
<farmall at lists.antique-tractor.com>
Sent: Wednesday, January 20, 2010 6:01 PM
Subject: [Farmall] More Magneto Woes


> Hello,
>
>
>
> I replaced the coil and coil cover on the IH H4 Magneto on my Farmall 
> Super
> A.  I finally got it together, and tested it.  I hooked a spark plug up,
> with the tip of the plug next to my vise, and spun the mag.  I got a 
> decent
> blue spark, so I know the rascal worked then.
>
>
>
> I was about to reinstall the mag, and I decided to test it once more.  I
> have not seen a blue spark, and I am repeating the same procedure that I 
> did
> before.  I wondered if the spark plug was bad, so I pulled another plug 
> and
> tried it.  No spark, no nothing.
>
>
>
> Is the condenser bad?  I did not replace it; maybe I should have done that
> as it is.  I sure hope I did not destroy my new coil!
>
>
>
> Thanks,
>
> Ben Wagner
>
> _______________________________________________
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> http://www.antique-tractor.com/mailman/listinfo/farmall


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