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Magneto on 1948 Farmall M

P

Picklesmith

New User
I have a 1948 Farmall M with magneto ignition. The tractor has run well for about 2 years. Recently, I have not been able to get the tractor started. I have determined the starting problem to be related to ignition.

By removing a spark plug wire, I can tell that there is no spark being delivered to the spark plugs. Additionally, there is no spark being delivered to the distributor by the secondary lead out from the magneto.

I can time the magneto to #1 cylinder per IH instructions. I have also changed the condenser (and the points), but I still get no spark.

One oddity that I did notice: I can read continuity between the condenser terminal screw and the tractor chassis as though the "kill switch" has the magneto grounded. Removing the wire from the ignition switch to the terminal makes no difference---the magneto still seems to be grounded. Internally, the magneto seems to be in good order with no wires to the condenser touching the case.

Does anyone have suggestions or recommendations? Appreciate your help
 
Is the impulse coupling making a snap noise when cranking? if not that is the issue. The impulse coupling causes a spring to wind up then release when the timing is just after TDC. The spring whips the magnet quickly making enough voltage to fire the plugs. Do you hear it snapping at cranking speeds? Jim
 
I'll have to check about the 'snapping' noise when cranking. However, I can hear the impulse coupling releasing when I time the magneto to the engine, so I believe the spring is ok. Also, I can move the impulse coupling counter clockwise thereby moving the rotor, but I cannot move the coupling clockwise because of the resistance.
 
Want to thank everyone who offered advice/suggestions. Turns out, the "new" condensor was bad. So much for Chinese manufacturing prowess....
 
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