[wendy]

I think my pulsar coil breaks down with heat, but not sure. I have a brand new one arriving on Monday, the seller stating that it meets factory specs for resistance.
.5 volts is an extremely poor signal, almost all electronic switching devices need around 5 volts to activate. I would dearly love to see a schematic of an igniter box.
The folks that have used the HEI units are using the stock coil with the .5 volt output? I have seen a few videos from manufacturers of pulse coils of the relatively same physical size as EZGO coils producing as high as 12 volts.
I ran a test on my lathe a few months ago with some pulsar coils, including one from a Yamaha 70 hp outboard that was almost a perfect copy. I made a bracket to mount the coils on the cross slide that would hold the coil over the perimeter of the three jaw chuck. Each of the channels for the jaws on the chuck were similar to the notch of the flywheel on the engine. With this setup, I could vary the gap between the coil and the diameter of the chuck while the lathe was running. With the EZGO coils, I got from 0 to .3 volts at the best gap. With Yamaha coil, 1.5. So that is what I put in the engine. I've had so many coils on and of that engine I had to heli-coil the mounting holes. Anyway, once installed on the engine, it put out .6 volts both at the gap established by my test and at the .030 gap.
It ran, though. Until it didn't. Once out, I am going to set this coil up in a vise, hook it to the Ohm meter and put a heat gun on it to see if it has an effect. Just to see. (Providing it does not read 'open' when I start...)
An engineer made for me a schematic to replace the igniter box that will provide a 11-12 volt signal that will open a switching device via the impulse coil signal, providing the ground path for the ignition coil so if all else fails, it will be an interesting experiment.
I am quite jealous of all of you not having to endure this odyssey.
And thank you to all that have responded.