Magneto Identification and Testing

The John Deere "E" and the International "LB" are examples. Most engines can be started by turning the flywheel by hand. This includes all of the engines using the WICO model "EK" magnetos. On this magneto, keep in mind that there must be a spring action pulling the armature from the core poles. Just pulling the armature to separate it from the magnetic poles without the spring action would not produce a good spark. When starting an engine by turning the flywheel by hand, the direction of rotation is important. On most engines of the two-flywheel design, the direction of rotation of the flywheels was so called, right-hand rotation. This direction was accomplished, on horizontal engines, by standing at the rear of the engine-opposite the cylinder head and valve mechanismplace your hands on top of the flywheels and pull toward you.

Any magneto with an impulse coupling could be checked easily for a good spark by removing the spark plug cable. On multiple cylinder enginesfrom the spark plug that is ready to fireturn the flywheel in direction of rotation, and with the cable held 1/8-inch from the engine block, when the impulse coupling trips, there should be a good blue spark. Engines using the WICO "EK" magneto should produce as good a spark as the impulse coupling type using the same procedure when the armature is tripped.

Low tension magnetos are more difficult to check. On the John Deere "E" engine with a gear drive magneto it was necessary to spin the flywheel to get a spark. Keep in mind, this was not a high tension spark. It would not jump a gap. The spark was produced by interrupting a current flow. This could be checked by removing the magneto lead wire from the igniter and scratching it along side the engine block as the flywheel was turning rapidly. Sparks should appear as you moved the wire back and forth along the engine block. It is well to remember that the rotating armature type of low tension magneto had to be timed to produce a good spark. On the John Deere "E" the magneto can be timed by pressing in the timing pin marked "L" in the magneto end bearing. Turn the flywheel slowly and the pin should drop in a shallow notch just as the igniter trips. The igniter had to trip when the spark line on the flywheel was parallel with the exhaust rod.