I have a 1918, the coil box has the battery/magneto switch on the front of it. It has always (since 2003 or so ) given me a little tingle when I switch from battery to Magneto. If my left arm or fingers are touching metal, such as a screw on the steering wheel spider, the tingle increases. I have gone through the coil box which has a plastic back and even changed out the switch. I could just put rubber on my key, but that does not really fix anything. I need some ideas. Thanks.
The battery or magneto does not put out enough electricity to shock you, but the secondary of the coils is what fires the spark plug.I would look for some arcing or connection between the secondary and the coil box itself. Your car should have a wood firewall, so that secondary voltage would not affect the performance of the spark plug. Only when it finds a path to ground would it cause a problem. When you touch the coil box, your body becomes the path to ground. One way you might be able to find the problem would be to connect a temporary wire between the coil box and the a ground such as the engine or chassis. Then try to start the car. The engine should then misfire. Whichever spark plug is misfiring, would be connected to the suspect coil. Look at the contact inside the coil box and also at the coil itself to see if you can find the source. If you rotate the position of the coils, and the misfire moves with the coil, your problem is in that coil. If it stays with the same spark plug, you have a problem in the coil box.
Is it possible the coil is earthing through the battery side & not the timer side?
Sounds like a good anti theft devise.
Thank you Norman.