Ford ran millions of internal resistor coils for at least 30 years, on street machines! The only disadvantage with them is a slightly lower spark voltage during starting because it's impossible to bypass the resistor while the starter is running. If battery voltage drops to 10 volts during cranking, for instance, the internal resistor reduces this voltage even more, resulting in a weak spark when you need a hot one most. GM systems used the "S" terminal on the starter solenoid, or the "S2" terminal on the ignition switch to bypass the resistor and put straight battery voltage to the coil primary. When the starter disengaged, the resistor kicked in and dropped the voltage back to approximately 9.5 volts to the coil primary terminal during normal running. This saved the points from premature failure with the low-resistance coil primary winding.
Jerry
Last edited by Hotrod Lincoln; 07/09/2008 12:27 AM.
