Jason, yes the voltage spikes and leaving the ignition on without the engine running are the main causes of failure.I'm thinking the voltage spikes are from generators or alternators with mechanical regulators.Guys using later alternators with solid state regulation don't appear to have a problem from what I hear.
Don't take me wrong, the GM HEI is a good unit for inlines,especially if the ability to run a wide spark gap is benificial for certain siuations, like to fire off lean fuel mixtures at low speeds due to cam or carburetion tuning.
Have you checked the Petronix website? maybe they offer a 24 volt unit?
