Originally Posted by Sniper
When out to the 51 and took some measurements.

It's a 51 Plymouth Cambridge I converted to 12v negative ground using a Mopar alternator and voltage regulator. Stock points ignition with Mopar ballast and 12v coil.

engine off, key in run I see 12.2V at the battery (low, should be 12.8v ish) and 6.2v at the coil +, all grounds taken at the battery negative terminal.

engine running, 12.8V at the battery (low, should be 13.8v ish, need to up the idle speed) and 8.8v at the coil +, all grounds taken at the battery negative terminal.

Pertronix says 8.0v minimum. You barely have the minimum for a 6v system. You aren't still running the ballast?

A LINK to the Pertronix test pdf.

For some reason your voltage at the coil is way low.








Not really sure how to proceed at this point. Ballast resistor is there as is the voltage regulator. its a stock distributor with Pertronix conversion to electronic ignition.
Car did start up initially but was running horribly. Plugs were fouled. Changed plugs out and it doesn't even want to run. Like I said, virtually a faint to no spark.