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magneto advice

S

sgt bull

Member
I'm switching my '40 H back to its magneto ignition. I've disassembled, cleaned, repacked,and reassembled the mag, and have a bright, healthy spark. Problem is, the rotor bug seems to have a lot of play. Can't get a consistent spark timing running a timing light, and I suspect its in the rotor bug/drive gear.
Any suggestions on where to get a new rotor and the corresponding drive gear? Actually, the slot in the drive gear seems to be pretty worn and there is a fair amount of play in it. The rotor looks pretty good so perhaps just replacing the gear would suffice. How much play SHOULD there be in that assembly?
 
I Have a bunch of H4 mags I can get you some parts off of if you want to email me with what you need.
Jim
 
The rotor isn't causing your funky spark timing. The spark occurs when the POINTS open.

A loose rotor MIGHT cause some of the sparks to be weak, as it flops around but won't affect WHEN they occur.

Clamp the timing light over the wire from the coil nipple to the distibutor cap, which will take the rotor out of the picture, and see what the timing light shows.

(The light will flash @ 4 points, including the correct one, and you WILL be able to see the timing mark.)

You can fix the loose rotor with a little dab is silicone gasket maker. It will hold the rotor steady, and yet the rotor can be easily removed, if needed.
 
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