Pertronix flamethrower Slant six

The Flamethrower comes in 2 primary coil resistance values: 1.5 ohm and 3 ohm. The 1.5 ohm is to be used with the ballast resistor and the 3 ohm without.

I prefer using the 1.5 ohm with the ballast; the proper ballast when cold provides more coil current and thus better spark energy on cold starts. The ballast will increase resistance when running so that its resistance plus the 1.5 ohm coil resistance is about the the same as the 3 ohm coil by itself. I warm climates it won't make much difference, but in cold climates, the low cold ballast resistance really shows up in improved cold start operation. (Perhaps the comments from middle or southern California or AZ don't see the cold start temps and issues like here in the VA mountains or maybe where the OP lives.)

The key with a ballast is to use the RIGHT ballast resistor; most folks don't realize that there are plenty of wrong ones for the Mopar system. The best I have found is the OEM ones, PN 2095501. You can find them sometimes on eBay. The MSD 0.8 ohm ballast is the next best and the BWD RU19 is 3rd best. Using any others is a crap shoot on what running (hot) resistance you will have.