Pertronix II users

The other thing, is some cars charge battery at 13 volts, some 14, some higher, some lower, so run time voltage on these cars is all over the place. Mine is 14.75 volts after driving car around a while so on the high side.

Like Jim says above, go a little high on that primary resistance and that should take a lot of load off ignition module

I am running Pertronix Igniter I, 1.5 ohm auto parts store coil and .8 ohm ballast for total of 2.3 ohms. Pertronix Igniter I instructions say 1.5 - 4.5 ohms primary so I am right in middle of that range. I could bypass ballast potentially get more volts to plugs but would have more stress on ignition module. And my running volts are on the high side to boot too.