re: "I am lothe to put in a Pertronix as electronics inside a hot distributor doesn't make sense to me."
If you have a car built in the last 30 years the engine bay is lousy with "electronics" including, probably, an electronic primary ignition switch similar to a Pertronix (my 1979 Subaru had pretty much the same setup, and was reliable to a fault).
Yes, electronic components fail from heat on occasion, but mechanical parts fail from wear or breakage. Besides, the heat in a distributor is minimal compared to some electronic installations. I believe all Pertronix has done is adapt technology used in (relatively) modern cars--new cars use electronics exclusively, no distributor--to older implementations. I also suspect the Pertronix is heat-sinked to the advance plate.
The main difference between Allison and Pertronix is the Allison uses an LED and chopper block to detect distributor shaft rotation--hence timing--whereas the Pertronix uses magnets and a Hall Effect sensor . Both probably use a power transistor to switch the primary current.
Edited by Bob_Spidell (06/29/09 12:53 PM)