[Lynn Eades]

Basically, when you first turn on the key you get 6 volts to the coil, (for easy start) but as the resistor warms up the resistance increases, which lowers the voltage to the coil down to 4 1/2 volts. The normal operation voltage which the coil is designed to operate at. All that said, I don't know the specs for the resistor, however it is important to have the resistor when running the std Ford coil. If you run an ordinary 6 volt (or 12 volt) coil the resistor can (and should be) bypassed. Among the 6 and 12 volt coils there are those with the "right" internal resistance which will increase the life expectancy/ reliability of your ignition system. The details of which I cannot recall. This has been explained in depth by a very helpful auto electrician on the Fordbarn forum.