I am going back to the beginning Greg. I don't have the time to read through 21 pages of comments to see if this has been mentioned or not. My new to me 64 Polara has Mopar electronic ignition on it and I am experiencing a similar no start condition like you. You can jumper the coil + terminal from the battery + and it will start. The voltage drop while cranking goes down to 10.9 and 10.8 at the ECU. I am wondering what the minimum voltage is for the ECU's. I need to do a little testing. Does it have spark after a battery charge when the surface voltage is around 13v. or so? Could I provide an external 12 v power source for the ECU and the car would start? This theory is all about the starter draw pulling the battery down below the minimum operating voltage of the ECU.
@Dave6T4 mentioned that he replaced his old starter with a new style Nippon Denso and not only did it spin over faster, the car started easier. Like he said
"I think the old starter was pulling so much power, there was not much left for ignition system." I think he might be onto something. I might try the battery charge test first just to see what happens. If low voltage is the issue, a stronger battery sure could help. So could a news starter. Even a different ECU that isn't as picky about minimum voltage may fix the issue. I may end up going back to a plain old single point distributor with a Pertronix in it.
