I bought a 1945 Allis-C. It's got the Fairbanks-Morse FM-J4A magneto. I downloaded the service manual off this site by going through old posts. Here's my trouble. I removed the endcap from the frame of the magneto & filed my points. Now I have a GREAT snappy spark @ the breaker points. Now, I can't "time" the disributor gear to the gear in the cap that sets my timeing. The service manual says that there should be a single marked tooth on my distributor gear...I don't have a single marked tooth. If it was ever marked, it is long faded away. I do have a square keyway that ailigns that gear to the shaft, is one of the teeth on ither side the right tooth to line up the cap with? I'm stumped, I've got the tractor to "pop", so, I must be close, but, I can't get it to run.....I have a real good spark @ the plugs now & it is getting fuel....help please.

Hi, I have had the same problem and found the following to work for me: Looking at the square key way you mention, turn the impluse to place the keyway at near 3 o"clock. Then count up (CCW) four teeth. That should be the marked tooth. I then remark it with a little nail polish (borrowed from my wife, of course). It stays in place quite well. For those that had a beveled tooth marking you can recheck with a magnifing glass and perhaps see the old bevel.

remove the # 1 spark plug and get the engine on tdc( when the air comes out of the plug hole) then put the rotor at the # 1 position and put the 2 parts together. that will have you timed. Bob

Try this link for timing a mag. I have a B that I ran into the same problem and this is what I used to time it.
http://www.worldpath.net/~thompson/acb/magtiming/magtiming.htm

• Untitled URL Link

Here are pics from Duey.

• Dueys Mag Pics

Depending on how its mark the mark can be a little bevel on the gear, a punch mark or a white line which could be rubbed off