Allis Chalmers mag question

[Mike Monnier]

I'm posting this for a friend. He has an Allis Chalmers B & C that both need work on the mags. He said the B has a very faint spark and the C has nothing. He's replaced the condensers in both, and says the distributor cap and rotor both look good. He's thinking about tearing them apart and replacing the coils next. I know just enough about single cylinder magnetos to be dangerous, but I'm completely at a loss with tractor mags. I'm looking for suggestions to help him out. Thanks, Mike

[Smoke]

How about the points in the mag. Maybe they need a little cleaning. Just a suggestion.

[John Wilkinson]

Really old man told me to fix a weak spark file the points a little bit then re-set the gap to specs and you'll get a long spark.

[Dempster]

Clean or replace points new. Gap to .015 for Fairbanks Morse X or .020 for FM J which is the most common mag on AC tractors back then. Could be a Wico, Bosch or other too. The coils are bad about going out on the FM mags especially the later orange expoxy ones and even the news sometimes aren't much improvement may be better with another good used coil. There are snap rings in behind the bearing on rotor shaft on that FM mag behind the seal has to come out before taking everything apart but coil will come out without doing that. Some online manuals that may help. If these don't cover you mag message me and I may have the info you need.

http://www.worldpath.net/~thompson/a.../magtiming.htm

http://www.oldengine.org/members/die.../PetrolMag.htm