Dave,
I am no electrical expert but I do want to share a couple anecdotal experiences;
With a brain that went blank, I was replacing the battery in my 1947 Model 509 Diamond T and installed it with the negative post grounded. It is a positive ground truck. Upon turning the ignition switch on, and before I could hit the starter button, I heard quite a racket coming from the firewall. I had totally fried the original Autolite voltage regulator.
After driving from Minnesota with my newly acquired 1950 Chevy COE, I was unable to start the truck to get it off my trailer. The engine turned over, I fiddled with various switches, tried the lights (they came on), ect. Would not start. In the middle of the night I woke up and was pondering my dilemma. I recalled that the ammeter went to charge with the lights on. At first light I went out, switched the battery polarity (it had been installed by the previous owner with the positive post grounded). The truck started right up. I have since learned that reversing polarity drops the voltage from the coil but that it may run fine.
I assume that Delco and Autolite regulators are not identical and that the latter are not tolerant to polarity reversal
