car54,
Some type of voltage reducer is required before the points to drop the voltage to approximately 9 volts when the truck is RUNNING. This reduced voltage is sufficient to power the ignition system WITHOUT burning up the points.
This feat is accomplished with a resistor before the primary side of the coil, or with a coil containing a internal resistance.
With a external, or ballast resistor, the system is wired to bypass this device when in the START mode, thereby supplying FULL voltage to the coil to overcome any draw created by a cranking starter.
This only pertains to a 12 volt system. Clear as mud to me!
Stuart
