But Mad North-Northwest
Join Date: Sep 2003
Location: SF Bay Area, CA
A ballast system is really only there to provide more spark energy when starting. When you're starting the engine, the ballast resistor is bypassed and the resistance is just that of the coil, the point being you get better spark when the voltage drops from cranking. During running the ballast resistor is in series with the coil and raises the overall coil resistance to limit current. Basically you can have a low-resistance coil when starting and then not melt your points once the engine is running.
With modern electronic ignition systems like the 123 there's really no point (ha!) in using a ballast any more. The 123 can handle a coil down to 1 Ohm.
So if you really want lower primary resistance & more spark energy all the time you can just use the 1.5 Ohm Flame-Thrower (40011) without a ballast resistor. This is probably overkill for a 4-cylinder engine, though, and 123 recommends a 3-ohm coil for street applications and a 1.5 for modified high RPM 4C cars or V8s, where the coil dwell time is lower.
The 3-ohm Pertronix has worked fine for me on both Alfas I have it on with the 123, but they're both pretty stock.
1963 Giulia Spider (1750 engine)
Former: 1987 Milano Gold