Just throwing this out there. It is not a matter of IF and electronic device will fail, it is a matter of WHEN it will fail. Both the HEI and the MSD are electronic devices and are susceptible to failing and as ka0tyk pointed out, it is always “at the worst possible moment.”
If you would like to run the MSD, you can always make an emergency backup pigtail and HEI module (mounted to an aluminum plate as a heat sink). It is small enough to keep in a water tight plastic box such as where I would keep an extra set of spark plugs etc.
You could always go for the cool factor and wire in two MSD boxes NASCAR style. Carrying a backup MSD box is an option too. If you do go the HEI route, I would also carry a backup HEI module.
Another option, that will bring on the controversy, is a Vertex magneto. Simple, reliable, and self contained. It only uses one ground wire to “turn it off” and no power is required as it generates its own. The most common failure is internally shorting out the coil from too much resistance i.e. resister core plug wires, resister plugs, and too wide of a gap (.019 recommended). The electricity has to go somewhere and if it can’t go through the plug, it will make its own path internally. Another common failure, in a car, is de-energizing the magnets by welding on the chassis while the mag is installed or polishing the mag body.
Cheers,
Joe
