Letters to the Editor

Reconsidering the Farmall kick: Farmall magnetos had condensers


| January 2009



Farmall

I just finished reading the November 2008 issue of Farm Collector. Regarding the letter "Another theory on the Farmall kick":

With all due respect to the different opinions concerning magnetos, starting with the impulse: The impulse performs at least two very important functions. When the latch engages it stops the magneto from turning, yet the drive shaft is still turning and winding a strong spring. This retards the spark the correct number of degrees, 35 on a Farmall. This prevents the engine from kicking or firing too soon, or before top dead center.

When the latch releases, the tightly wound spring gives the armature a quick twist, which produces a very hot spark at top dead center. After the impulse is released, the spark will fire 35 degrees before top dead center. The E4A and F4 mags have 35-degree lag angles on the impulse, which also means 35 degrees of advance after the latch releases.

The E4A mag definitely has a condenser. It is hard to see because it and the coil are both located in the armature!

The breaker assembly also turns with the armature and operates off an internal cam in the magneto frame.

A very important fact about magnetos is that different engines and different magnetos quite often have different degrees of lag angle and advance on the impulse. Lots of times most any old mag can be made to mount on the engine.