Servicing Magnetos

From the 1957 H.G. Makelim catalog


| March/April 1987



Makelim Magneto Test Benches

Plate No. 8: Showing the spark gap setting for spark rack on Maeklim Magneto test benches.

The following article was sent in by Craig Roy of 1513 Beach St., Salina, KS. 67401. It was originally published in the H.G. Makelim Co. 1957 catalog, and is being reprinted here with permission from Chuck Hess, whose father bought the company in the late 1950s. Unfortunately, the company stopped production of magneto test equipment in 1977.

A brief history
In the days of the Model T Ford practically all automobiles used magneto ignition. Some, like the Ford, used what was known as low tension magnetos. Low tension magnetos practically passed out with the passing of the model T. However, Scintilla Magneto Company is again making low tension magnetos that are being used with success on some types of heavy duty stationary and marine engines where extra long spark plug cables are necessary. This is due to the fact that much of the heat value of the current in a high tension magneto is dissipated in the long spark plug cables.

The writer learned magneto repairing in the days when such swanky cars as Stutz, Lozier, Mercedes, Winton, S.G.V. and many others used magneto ignition as standard equipment. In those days magneto service stations were as numerous as battery service stations are today. Cars came without starting or lighting equipment and the hand crank was used to start the car. When storage batteries came on automobiles it was found that the battery could be used for starting and lighting and it looked like the magneto business was doomed. Slowly but surely one automobile manufacturer after another discarded the magneto and used battery ignition. Batteries furnished light, ignition, and power to start the car whereas the magneto furnished only ignition. Many service shops sensing the end of magnetos gradually discontinued magneto service and went into the battery business. However, there were many places where batteries did not prove as efficient and reliable as magnetos. Farm tractors were coming on the market in great numbers and the storage battery did not stand the rough treatment and neglect generally given by a tractor operator. Plowing rough fields would crack battery jars, batteries would run down, plates corrode when not in use and they had to be constantly recharged, etc., so magnetos began staging a comeback on tractors, industrial equipment, outboard motors, concrete mixers, fire engines, racing cars, airplanes, Army tanks, etc., where a reliable self contained ignition system was essential. What was considered a dying business twenty-five years ago is now a very live and growing industry.  

Today there are seven or more prominent magneto manufacturers and one of these has built three million magnetos in the last ten years. Another manufacturer has built in the neighborhood of one million flywheel magnetos. There is a widespread use for flywheel magnetos on lawn mowers, scooters, wood saws, washing machines, wheelbarrows, small compressors and lighting units, etc. You can readily see that there is going to be a lot of magnetos in need of service for a long time to come.

Modern magnetos
There are three different types of magnetos in use today, namely: Shuttle wound types, inductor types, flywheel types.

In all shuttle wound types the high-tension coil or winding spins around with the armature while the magnets remain stationary.