Built In Ballast Resistor In Ignition Coil
So with MSD 6A box, blaster 2 coil and their billet distributor no ballast is needed?
You have to understand that MSD is a CDI (capacitive discharge) design, which is completely different than what some of us call a "switching" design.
To get things down to the very simplest terms, breaker points, GM HEI, or Mopar ECU systems, as well as most single coil factory systems, Run power to the coil positive terminal, and the system SWITCHES the negative coil terminal to ground to generate the spark. There's more to that, but sort of.
CD (Capacitive Discharge) systems do not do this
MSD charges up a great big capacitor, similar to a camera photoflash. The trigger mechanism "fires" the ignition, which disharges the pulse of power from the capacitor through the coil.
The coil then, becomes a TRANSFORMER, with CD type ignitions, and has NO direct current (12-14V) through the coil at all.
There is WAAAAAAYYYYYYyyyyyyyy more to it than this but that is the very basics
THE REASON that a "switched" system NEEDS to "worry" about coil resistance and a ballast resistor is that
with older breaker points systems, there is a practical CURRENT limit before high current from a great big coil will destroy a set of points
The same, in some ways, is true of most "switched" systems such as the Mopar ECU. That box can only handle so much current. If you put a VERY low resistance coil on it with no ballast to limit current, you may very well burn up either the coil or the ECU
