Farmall Cub Backfiring - Update

Hotflashjr · Aug 17, 2018

So I got rid of the backfire... but that brought me to now no spark. This thing is giving me fits. Last time I posted an update I had spark but the timing was off. Took the mag off the tractor, followed a very helpful youtube video and the manual to re-time the mag. I now believe I have the mag timed correctly but... no spark to the plugs. I gave up when I realized the spark was gone. I put the old condenser back in to see if that made a difference - nope. Disconnected wire from the on/off switch, no difference.

Any help is appreciated.

Janicholson · Aug 17, 2018

Possibly internally grounded lead from the coil. If both of the coil primary leads are disconnected, it should have continuity. Jim

moll · Aug 17, 2018

I had similar problem with two tractors, similar H-4 magneto.
The wire to the coil was touching the points cover when installed.

gene bender · Aug 17, 2018

mag was working then you retimed it now no spark So in the process you have done something to the timing and no spark to the plug. Better rake the cap off and look where the rotor is pointed when it snaps the rotor should be pointed at the tower where the wire goes to the plug. Now make sure you are on #1 compression when the rotor snaps with the rotor pointed at the tower going to #1 you can be off 180 deg Your problem is with mag timing cause it did run before you changed something go back and start over

Farmall Cub Backfiring - Update

Hotflashjr

Well-known Member

Janicholson

Well-known Member

moll

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gene bender

Well-known Member

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