Reply To: 1927 Johnson A-35 Ignition Coil – What to do?

[jeff-register]

Tom is so correct!
The winding either sec or primary has just two ends per winding. The secondary winding in this case both ends of the winding both go to the spark plug outputs or hi-volt leads.
Electricity looks for the easy path to ground, in this case the spark plug gap. There are differences of resistance which the one with the least will arc to ground providing the winding energy still saturated firing the second spark plug. If you had only one spark plug it’s possible to ground one hi-volt to produce twice the energy. 50% less resistance = 50% more voltage.