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International Harvester E4A

The E4A was and still is  very credible magneto offered by IHC.  It probably worked very well in the day. It used ball bearings, an impulse coupler,variable timing and a stop switch built into the timing adjustment mechanism. They were quite hot and reliable and were equipped with a safety gap in case a plug wire came off. They initially used the Splitdorf type impulse coupler carried over from the Splitdorf Dixie Aero magneto used in earlier tractors. It was a manual reset impulse that suffered from the usual lack of lube and care, and was exposed and often covered in grease and dirt. Later versions used a much more robust and enclosed impulse with automatic reset.


They were a wound armature design and like many sometimes had the usual woes with insulation seepage and sticky goo. Points are set at .015".

When sticky goo appears, its time to rewind.


The condenser lives in the base of the rotating armature and the points lived on the end. Always check for leakage forst, then for capacity. if it is leaky, replace it. Most found will be defective,especially in the soggy Northwest. A 0.22MFD 400 Volt polypropylene film  SBE Orange Drop capacitor will work well and last forever. You can poke some Bondo in the space around it to prevent vibration.


The E4A can be a challenge to get apart. The main concern is to be patient and use heat.  If the armature is stuck, put the whole mag in the oven and get it up to 300 degrees. The aluminum housing will grow at a faster rate than the steel armature and the sticky goo should let go to free the armature. Remenber to remove the Woodruff key on the armature drive shaft or it will broach a slot in the magneto housing on the way out. If the screws on the name band are stuck, add some heat in the base and they usually let go.They can break easy if we get too ornery with them.Use an impact driver with care, lest we need the helicoil procedure. If heating the base does not make it let go, repeat the process and get the head of the screw red hot carefully not to damage the name band.


If the magnet is stuck, best to be patient as they are quite hard and brittle. The best way is to use a piece of bar stock on the ends and give it a good smack. Give the same treatment to each leg of the magnet and it should let go and gradually slide up.Always use equal force on each leg of the magnet to prevent breakage. It may be tight due to rust on it and the magneto pole shoes. Avoid heat as this can destroy the orientation of the magnet. When you get it apart, blast off the rust and give it a good coat of primer and paint, leaving the magnet surfaces that contact the magneto pole shoes masked to assure good metal to metal contact and maximum magnetism. Also give the pole shoes a light blast or polish with emery cloth. When the paint is dry, apply a thin film of grease to the pole shoes and magnet contact surfaces. this will make it slide together easily. The position of the magnet is not critical, but they come from Michigan Ave with the logo on the magnet on the same side as the safety gap screw. As always when blasting, be extra sure you get all the abrasive out of the bearings, machined surfaces and threaded holes before reassembly.


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