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I am currently working on a Cadillac 390. I am not getting spark. I have replace the points with a pertronix twice, replaced cap and rotor, plugs, wires, replaced the coil twice.

I am getting 9 volts to the positive side of the coil when cranking. I ran an extra ground from the negative side of the coil to the carb stud. I also ran a full 12 volts from the battery to the positive side of the pertronix ignition.

Still no spark, what am I over looking?
 

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Not sure about the rest of it, but the negative side of the coil should not be grounded. There is a ground wire that needs to be in place (at least on Ford 390s) within the distributor:


Maybe go back to points until you get it running in case the module is fried. Running a wire from the battery to the positive side of the coil is good for testing. 9 volts is low - maybe the battery isn't great? Can you try jump starting from another car?

Pat
 

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Using a test light with the ground to the block or the negative terminal, positive side should light up while cranking and key on. Negative side should flash. If negative side doesn't flash, you have misadjusted points, bad points, bad condenser, bad pigtail to the distributor or sheared a pin in the distributor. (rotor won't turn)

Grounding the negative side the way you did will unload the coil continuously and you won't get spark, a distributor IS the intermittent ground that tells it when to spark
 
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