| A ballast resistor keeps voltage down and makes it easier on coils and
contact points.  If you have a good aftermarket coil and electronic
"breakerless" ignition then you don't need a ballast resistor.  Of
course, follow the directions of the equipment you use.
An average car with alternator has about 13.5 volts in the system when
running.  A ballast resistor lowers the voltage through the ignition
circuit to somewhere around 6-8 volts, which is plenty to run ignition
systems designed to use a ballast resistor.
 |