Ballast Resistor

The reason the ballast doesn't do as much as RPM's increase, is that the number of spark events becomes closer together as RPM's rise, and when this occurs, less time in micro-seconds for the coil to charge, the points see far less current loading. This is why things like an HEI, other electronic systems use far more current at idle and lower RPM's, and a lot less at upper RPM's. On one of my HEI systems, loading on idle is 4 to 4.5 amperes, at 3K and higher, load lowers to 1.25 to 1.50 amperes. Reason: higher RPM'S do not have the charge time between firing events for the coil, lower load, lower amperes used.

This is why we designed the HEI as what it is, an electronic system that allows the coil to saturate more than other electronic systems, for more fire power at higher
RPM's, but, HEI is NOT a race system, it was designed strictly as a 4K RPM limit higher output system to match leaner fuel/air curves, FOR EMISSIONS USE ONLY, nothing else. They ain't race ignition systems.

If you want to do a race system, Capacitor Discharge is the way to go. CD's don't charge the coil with current for each firing event, the capacitor charges, then tells the cold, uncharged coil to "make spark now, 40 K output", then goes on to the next firing event, does it all over again.