I had an old rally pack from an early mustang hanging around and wanted to try it on my 55, however, every time I tried to hook it up it would kill the car. I have petronics, is this a problem and does it have to run behind points???

55 Vicky & customline

58 Rack Dump, 55 F350 yard truck, 57 F100

59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?

Bill:

The old Rally Pack tachs are different from the run of the mill aftermarket ones.  They have to be wired in series with the coil, not parallel.  I doubt if they will work with a Pertronix because the current in the coil circuit is so low with the electronic ignition.  Probably better to sell the Rally Pack to a Mustang guy and buy several modern tachs with the money.

John in Selma, IN

John - "The Hoosier Hurricane"