[Healeys] Lucas Sports Coil

[Richard Ewald]

You are 1/2 right.
If it didn't matter, then they would not have put ballast resistors (either
internal or external) into the ignition systems. If you use an internally
ballested coil on a system with an external ballast resistor, the points
won't see enough voltage, which wile the distributor won't care, the spark
plugs might.  Not enough voltage in primary = not enough voltage in the
secondary, which can lead to a miss-fire.
If you use a coil that requires an external ballast resistor on a car with
no external ballast resistor I can assure you that the distributor will in
fact care.  A lot.  The points are not designed to switch full system
voltage, and if there is not ballast resistor in the system (external or
internal) the excess voltage will lead to excess arcing of the points and
them burning out very quickly.  In the case of an electronic system will
this cause issues?  I don't know as I am unfamiliar with the particular
system being discussed.  On some electronic systems, you might pop a power
transistor.

You are correct that an external ballast resistor system has a bypass
circuit during starting, so that the coil see full voltage during crank.
The reason for this is, full system voltage during crank is in the 9-10 volt
range not 13-14 like when the car is running.  The starter motor drags the
battery voltage way down.

On Sun, Feb 22, 2009 at 8:31 AM, Bob Spidell <bspidell at comcast.net> wrote:

> Don't ballasted systems require two primary circuits; i.e. one for starting
> (non-ballasted) and one for running (ballasted)? The distributor won't care,
> as it switches the primary circuit--12V or otherwise--to ground.