H4 Magneto puzzle .....

Crazy Horse · Sep 13, 2012

My Farmall A has a magneto problem, not only a problem but more of a puzzle. When test turning the engine slowly with the hand crank, I get strong spark from all four plug wires, yet when spinning it with the starter and then once it "starts running", the tractor runs only on two cylinders and occasionally on a single cylinder. So once the engine turns at speed, the mag fails to fire on 2 or 3 terminals. Can't seem to trouble shoot this myself so I need help.

Anonymous-0 · Sep 13, 2012

check the cap for cracks

Haas · Sep 13, 2012

It sounds like you are 180 degrees out of time. If you have had the mag off the tractor and reinstalled it, it's easy to get it 180 degrees out of time because there are 2:1 gears between the points cam (which only has two lobes) and the rotor. Check your timing to make sure the rotor on the distributor is pointing to the correct plug wire at TDC of the compession stroke for each cylinder. Firing order 1-3-4-2. If it is 180 degrees out you can correct by reconnecting the plug wires, or best is to just take the mag off the tractor and turn the drive 1/2 turn and put the mag back on.

teddy52food · Sep 13, 2012

Clean the points. Gap them at .012 to .015.

gene bender · Sep 13, 2012

Sounds like you got it as he is 180 out if it runs on two cycls

H4 Magneto puzzle .....

Crazy Horse

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Anonymous-0

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Haas

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teddy52food

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gene bender

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