Having a couple of problems, maybe related or 2 different problems? A little about the build... 505 stroker, about 11.5:1 compression. I have a Powermaster 1 wire 75 amp alternator, never goes over 12 volts on the voltmeter? And a Optima yellow top battery 750 amp, have to turn off ignition until cranking and than flip on the ignition to turn it over. Any ideas?

Disconnect the battery cable and measure the voltage
at the battery... connect the cable back on... start
the engine and measure the voltage at the battery again
and see if its higher

From what your describing your Alts not charging and your Bat is discharged to XX amount of volts.

With your engine running you should be able to measure around 14 volts +/-. The bat fully charged should measure 12.75 +

Start with the Alt.

Mopar Ray I just went thru this with my car and Powermaster alternator. I have been told that the internal voltage regulator is usually the culprit. Had mine rebuilt but it only lasted a short time so I just ordered a new one from Summit(had to have one quick to be able to race) and will have the old one rebuilt(voltage regulator) again and keep it for a spare.
Mike

Thanks, Think I am going to step up to a 140 amp anyway. We''' see what happens.

IMO it sounds like poor grounds.