GM style HEI

Eric Mulay said

But won't that give constant power to both lines if you just hook them together? And one isnt supposed to have constant power?

Click to expand...

No. IGN1 is hot in "run." It goes DEAD in "start"

IGN2 is only hot in "start."

Why?

Because when you twist the key to "start" and if there was no IGN2, the coil would see battery at cranking voltage minus the drop through the ballast = VERY low coil voltage in "start" perhaps less than 6V

So IGN2 jumpers full battery voltage from the key direct to the coil in "start." Since the battery sags during cranking, this means the coil gets around 10.5--11.5V during cranking.