I have a 1957 Ford Distributor and a Pertronix I in my TBird.  I also have a Pertronix 1.5 ohm coil with no external resistor.  I experienced an intermittent miss that went away when I disconnected the O/D wire.  It did not blow the Pertronix Unit. The O/D kickdown switch is an open switch located in a place where corrosion, oil and grim can get to it.  The way I drive my car, I have no use for kick down.  Downshifting when I want to pass works for me. Since disconnecting the O/D wire, my car has been running for over a year with no issues.  If you blow the Pertronix unit, you are dead in the water.  You can carry an extra unit or reinstall your points. To me, having a working kick down circuit is not worth the risk that I will be sitting on the side of the road with a flash light and a screw driver.

To be honest, I have never experienced a Pertronix unit failure and I have used a bunch of them over the years.  At the same time, I have experienced numerous failures of Chinese points and condensers.

Make sure You use at least Pertronix 11(2)

  

thanks for you reply maybe i just over thinking

Agree with Dobie. Been running Pertronix 2 with O.D. for 8 years with no problems.

Ben HessTulsa,OK

Untrue. All my OD equipped vehicles run Pertronix ignition with absolutely no problems.

I have read that the kick down on a 3 spd OD can cause problems with the Petronix ll  ignition.  That if you kick down it will burn out the system.  Has anyone had problems with this?