magneto testing

Mon Apr 04, 2011 9:46 pm

I pick up a fair banks morse magneto off an allis chalmers at an auction and am wondering how to check it out off the tractor. Is it supposed to throw a spark when it snaps by turning it by hand? thanks, ron

Re: magneto testing

Mon Apr 04, 2011 10:14 pm

I have a procedure but not the link to send you. Try the allischalmers.com forum. Plenty of information available there. Hope this helps. Stan

Re: magneto testing

Mon Apr 04, 2011 10:52 pm

Ron:

Try the GSS-5035 Service Manual Magnetos. Might help.

Re: magneto testing

Mon Apr 04, 2011 10:56 pm

my allis throws a good spark when turning by hand

Re: magneto testing

Tue Apr 05, 2011 12:51 am

Yes, supposed to spark when impulse snaps. Guessing it's an FMJ4B. There is no external wire from the coil to the distributor. The link between the coil and the distributor is through the lug/lump at the top of the distributor cap.

Search the internet for Fairbanks - Morse magneto testing. There are several videos showing how to bench test them. Work of caution. Be sure to use a plug wire and spark plug in each distributor cap location and ground each spark plug to avoid shorting out the coil.

Re: magneto testing

Tue Apr 05, 2011 1:51 pm

Thanks for all the replies. ron :D

Re: magneto testing

Tue Apr 05, 2011 5:20 pm

If you lay that sucker on a work bench n hold it down with one hand and couple a variable speed drill to it and spin it you can find internal short REAL EASY :shock: :shock: :shock: :shock: Dont ask how i found out