Let's do some simple Ohm's Law calculations- - - - -the average HEI coil primary winding has about 1/2 Ohm of resistance. With an alternator operating voltage of 14.7, that gives a surge current of almost 30 amps before the inductive reactance of the coil winding and the current limiter kicks in. This happens every time the winding conducts, three times per crankshaft revolution for a 6 cylinder, or four times for a V8. That's pretty close to a constant 30 amp current flow in practical terms. I can see where a tired 50-something year old ignition switch might have problems, and an overseas-made aftermarket knockoff won't be much better. It makes sense to me to engage in a little overkill and use a 60-amp Bosch type relay and 10 gauge wire to carry the main coil current, and turn it on and off with a couple of amps from the ignition switch through the relay coil circuit. "Your mileage may vary!"
Jerry
