circa 76 dura spark with MSD blaster coil

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Gacannon

Active member
Joined
Sep 18, 2010
Messages
37
My 28 ford PU hot rod is using an old duraspark that works well.

The original wiring of the donor car used a length of resistance wire in place of a ballast resistor. This was with the original coil.

I put a MSD blaster coil in place of the original coil. I used a Borg Warner RU19 ballast resistor in place of the resistance wire. The RU19 cannot handle the watts and heats up. High voltage is fine and coil does no heat up.

Does the MSD coil even need a ballast resistor. I assume that the original coil required that the voltage be stepped down a few volts in the run mode. In the start mode, they bypass the ballast resistor with the starter sol. terminal I, which applies 12 volts directly to the duraspark.

Seems to me the ballast resistor is simply creating a I*R drop to reduce voltage to the original coil.

Any help from the forum is appreciated.

Thanks

Bob, Gacannon
 
ballast resisters do run hot.....

normally they are mounted so the heat is not an issue against wiring and such.... are you talking like smoking? But if it feels hot, they do.....
With points you need to run the ballast.... electronic does not need ballast.... per the MSD guide.....
 
You can run without either, but points won't last as long. I would bet its not good to run MSD on lowered voltage.
 
Duraspark and blaster coil

Decided to just go back standard. Not a special engine so no need for special things. I found the old coil and purchased the 61" ford resistance wire used on the original set up. Works fine. Am going to crank it this week. This build started from scratch with old parts and a few new ones.

Thanks

Bob in Ga.
 

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