Ballast resistor for new MSD coil?

[ESC79]

Quick question. Car is 79 sc. The coil (silver bosch) died and I'm replacing with MSD hi-vib. The instructions indicate I might need a ballast resistor if I have a 'stock style distributor'. Any idea if this is necessary?

thx in advance!

[timmy2]

I didn't need anything when I installed mine. 4 years running it now.

[Charles Freeborn]

I used the ballast resistor that came with the MSD coil as I still have the stock Bosch CDI. If you change to a MSD ignition unit you can eliminate the resistor.
-C

[timmy2]

Originally Posted by Charles Freeborn

I used the ballast resistor that came with the MSD coil as I still have the stock Bosch CDI. If you change to a MSD ignition unit you can eliminate the resistor.
-C

Interesting, I'm running Bosch CDI and no ballast resistor on my '78 with 6 pin CDI and stock electronic Distributor.
Difference between points and no points perhaps?

[ESC79]

Thanks!

I connected without the resistor and it fired right up. I have the original Bosch CDI as well.

[Charles Freeborn]

Someone with more electrical knowledge than I can explain. My car still has points, Bosch CDI and otherwise stock other ignition systems. I'm running the resistor and it performs well.
I have the MSD unit ready to install when I have the time do do it cleanly.
-C

[wwest]

The term "ballast resistor" in this context means the current limiting resistor used to limit current flow through the coil during normal engine operations. Bypassed during "start" to compensate for expected battery voltage drop with heavy starter motor load.

Only applies to actual Kettering ignition systems, NOT CDI.