This 55 Tbird I'm working on measures 6 volts going to the coil. Sound correct?? It tries to start..... It has been converted to 12v at some point in its life.

Coil resistance?? Can the capacitor be measured??

I plan to install a HEI type distributor, maybe sooner than later!!

 

All 1955 Ford passenger cars (Big trucks excepted), had 6-volt ignition systems, 6-volt batteries, and 6-volt generators, no alternators yet.

In 1956, Ford finally went to 12 volts. Instead of manufacturing new ignition coils wound for 12 volts, 6 volt coils were used with a voltage dropping resistance in series with the coil, which provided 6 to 8 volts at the coil, except during c ranking, when the full 1 volts was sent to the coil by bypassing the resistance, but only during cranking.

If your vehicle was converted to 12 volts, all lamps, bulbs, heater motor, radio, horns, etc. would been changed to 12 volts. Ignition resistor would have had to be used to feed the coil. This all assumes use of Ford production parts. If aftermarket parts were used, as sounds likely by your description, a thorough wiring check is in order, especially if it fails to start and run.

 

I agree 100% with what you stated very well, but what is the 'run' voltage to the coil with this Mallory dp?? 6v seems to low.

 

Have no answer for you, sorry. Maybe Mallory might help? Two things are very important for the coil: it must not operate with a higher than design Primary (points) voltage or risk shorting out of it's secondary winding.

I was always happy prior to electronic ignition if I could draw a 1/2" spark off a plug wire, and my coil did not overheat or burn out.