MSD ignition with ballast resistor

[Markie]

Why must ballast resistor be removed or bypassed with MSD ignition installation.

 

[mpgmike]

Because the capacitive discharge and multi-sparks take a lot of electrical energy, and the ballast resistor restricts it too much. That's my guess.

 

[Geoff 2]

The MSD instructions say it is NOT necessary to remove/bypass the bal res....

 

[chrger1967]

Why must ballast resistor be removed or bypassed with MSD ignition installation.

I have the same question for a Portronix II setup with a “Flamethrower” coil. I see MSD has a ballast resistor, can that be used instead of the original?

 

[DevEngNerd]

I still have not seen this answered clearly. If using a modern electronic ignition (coil, box and distributor) should a ballast resistor (stock or aftermarket) be used.

 

[451Mopar]

Why must ballast resistor be removed or bypassed with MSD ignition installation.

Which MSD? Ready to run or CD box?

With the CD box the Ballast resistor no longer connects to the ignition coil, but can be left in place, just disconnected from the coil.
With the Ready To run Distributor they want you to by-pass the ballast resistor for full power at the coil positive. Leaving it in place limiting current to the coil would likely work, but seems not needed and would lower the coils output.