My intention is to explain how to spot and repair a Webster Oscillating Magneto in terms that may help the layman in understanding and repairing this particular magneto.
They were used the most, as far as the author knows, in the years 1910-1920. They were used entirely for single cylinder low compression gasoline engines. They were designed to be easy starting and the most trouble free of any type of magneto that could be used on a single cylinder gasoline engine. While they required very little attention other than oiling occasionally, they undoubtedly would run the longest without getting out of repair than any magneto placed on a single cylinder engine.
The most important thing I want to get across to the average layman who starts to repair the Webster Oscillating Magneto, or finds that he has a Webster Oscillating Magneto engine that does not produce a spark is - there are usually only two things wrong. The first thing that generally goes wrong is the igniter points get out of adjustment. Then, if after the igniter points are properly adjusted you still have no spark, you can look for badly worn bearings on the oscillating spool by letting the spool touch the field pieces thereby shorting out the lines of force. All that is necessary to correct the badly worn bearings is to remove the spool from the magneto and turn the shafts until they are perfectly round. Then bore out and rebush the worn bearings to fit the shafts. Ordinarily, that is all that is ever wrong with a magneto.
There is one thing to take into consideration in adjusting the points - the tension spring that closes the points is hooked properly where it should be hooked, and that it is not stretched until it is too weak to do the job, and that the points must be closed only when they are being tripped to make the spark. They should be adjusted in a shaded area to show the size and intensity of the spark.
There are cases where the horseshoe magnets are weak, but not as a rule. There is such a thing as the field coils could be bad, or an open circuit. To make the simple test to see if your field coils are all right or not, remove the magnets from the base of the magneto, being careful to mark them so they will go back in exactly the same position in which they came off. The best thing to mark them with is chalk, in case there are other marks that would be confusing. Thus, the chalk marks are the only ones you pay attention to.
The procedure for testing the field coils - all that is needed to make the test is a good six or twelve volts wet or dry battery and a simple six or twelve volts primary coil. Then you properly attach the positive terminal of the battery to the positive terminal of the coil with an ordinary insulated copper wire. Then attach a wire from the negative terminal or post with a copper wire from the coil to the outlet wire of the magneto coils. Then attach a wire to the negative post of the battery and striking it across the ground screw of the magneto coils. If you get a good spark, or a spark of any size, your coils should be in good order.
The next step is to test the magnets to see if they're strong enough to do the job. The best way to do this is toplace a screw driver or thin wrench across the ends of the magnet. If the magnetism is strong enough to hold its own weight in the air, it's usually strong enough to do the job. If when you place the magnets back on the base and when they are within fifteen or twenty thousandths of the base they grab, they are strong enough to do the job.
The next step to completely reassemble the magneto is to place the shuttle back into the magneto base and to replace the covers with the bearings on each side, then the end brackets on each end, with the spring connected to the fork on the outside. You should be sure the small rollers with the grooves are properly in place, and you should also be sure the shuttle is turned so that the long shaft on the fork is turned so the long shaft is to the right, with the outside of the magneto facing you as you're looking at it. With all four screws in each end bracket, and with the magneto securely bolted to the magneto bracket, and the lead wire connected to the points terminal, you are ready to test your magneto to see if it properly sparks. Then with the hand lever picked up and the long end of it under the long shaft on the bracket, you push down on the hand lever which raises or lifts that shaft upward against the tension of the springs, release the lever. When that shaft turns back to its normal position on the springs, a spark should occur between the points.
If you want to make sure that the spark that occurs is the right voltage, simply place a neon tester with one lead on the points terminal and the other to the magneto base at any point and you will get a real good flash in the bulb of the neon tester when the points break.
I hope by not going into complicated procedure or terminology, I have been able to help the average Gasoline Engine Collector realize that with proper repairing, the average Webster Oscillating Magneto can be restored to normal operating capacity.
Mr. Haynes hopes to make available a neon tester to those interested.