Coil / ballast

[kram350]

Have a 1.3 ohm coil (as measured), think it's an MSD unit. What ballast should be used with this coil? The internal ballast resistance wire in the car was removed, so need an external. Running a dual point. Any advice appreciated.

[Bob Gaines]

Have a 1.3 ohm coil (as measured), think it's an MSD unit. What ballast should be used with this coil? The internal ballast resistance wire in the car was removed, so need an external. Running a dual point. Any advice appreciated.

Typically aftermarket coils have a internal ballast resistor. They are designed to work on cars with or without ballast resistor in the cars internal wiring.  You would be be able would to tell if the coil during operation after a short period of time heated up significantly  indicating the need for a separate ballast resistor.Or you could just call MSD.

[Royce Peterson]

The problem with aftermarket coils is they are not compatible with factory tachometers. The resistance of the factory coil is listed in the shop manual. Whatever aftermarket ballast resistor that you use must match the specs for an OEM coil (coil + ballast resistor resistance). Otherwise your factory tach will be way off.