All stock 12v systems use a ballast resistor. It can be either inside the
coil, or outside the coil. If your car has an external resistor, you need a
coil without internal ballast. If your car doesn't have an external
resistor, you need a coil with internal ballast. If you have a 6v system,
you don't need ballast because all stock coils are designed to work with 6
volts. External ballast systems have a terminal on the ignitions switch to
bypass the resistor while starting. Internal ballast systems have a thermal
switch which bypasses the ballast until the coil warms up. There are
exceptions when using aftermarket systems...for instance, a Pertronix unit
will not work with an external resistor because the module needs a full 13
volts to function. The Pertronix coil has to use internal ballast which
lowers the voltage inside the coil while allowing the module to receive full
voltage. There are probably other exceptions when using various aftermarket
ignition systems, but the ballast requirement depends on the coil and not
the distributor or points.
BZ
|