Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

One test you may want to make is to take your spark plug out of the head, but hold the threaded part against the hole in the head where it mounts to ground it, then try touching the red wire that is cut off at the Reed switch to the top of the spark plug and see if that gets the plug to spark. If it does, then the black lead to the Reed switch is the same polarity as your ground so that it would seem that the lower arm of the Reed switch needs to have the red wire soldered to it, instead of the black wire ..... maybe.

Perhaps a safer way to test this is to use your voltmeter to check the voltage from the red wire to ground on the engine, and then also test the voltage of the black wire to ground on the engine and see which if any give you a voltage reading.

If neither the black wire nor the red wire provides a voltage reading when the meter is used to ground them against the engine, then I would think that your "coil" or "magic box" is the problem.