Classic/Antique Car Repair: 66 Mustang Coil Voltage Problems, ballast resistor, wiring error

Question
What should the voltage on the primary terminal of the coil be?  I keep burning up points and I am thinking the voltage on the coil maybe to high.  How should I test it?

Answer
The voltage on the + terminal of the coil should be between 4 and 7 volts with the points closed, and battery voltage (12.3 to 13) with the points open. If the voltage is too high, there is either a wiring error or your ballast resistor has failed.

If the voltage is in the right range but the points still burn out, check the connections inside the distributor, especially the ground on the distributor body and the connections to the condenser. If the condenser has not been changed recently, change it.

Dick