It sounds like your ignition switch contacts are getting corroded, this is the only reason for voltage drop. I had exact problem with my Parisienne years ago, i changed the ignition switch and never had a problem since. I too run pertronix.

hawkeye5766 wrote:

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Do you still have the stock wiring Jerel? Should be 9volts through ballast resistor or resistor wire with key on run and 12v while cranking. Losing voltage before coil so could be ign switch/resistor wire/ballast resistor etc. Could also be firewall bulk head plug. If you can get it to go to 4v again,work your way backwards until you get 12v. Also try turning your headlights on....could be a voltage drop with load to main fuse panel.Amperage draws over a long time through a poor connection will cause resistance, so might just happen over a length of time.

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 Yes, basically the stock wiring.  I just cut the original wire that provided the 9v and replaced it with a direct one from the ignition to the coil to provide the 12 for the pertronix.  I have a hunch what Pete said about the contacts in the ignition could well be the cause.  Just checked it now and it is at 12v again.

Read the istructions for the pertronix.  i have them too in my 64's.  If i remember correctly, you need to keep your original resistor wire to the coil to provide a lower voltage so the coil does not burn out.  Then run a totally separate new 12v supply from the fuse panel to your pertronix in the distributor.

the pertronix needs the 12 volts, but not the coil.

this might not pertain to you problem, but it might explain some things