I have a 1972 Mustang with a 351C auto.I replaced my points last winter with pertronix 1 and had trouble since. When it got below 20 or lower it would start fine but die when I turned on the headlights, replaced the old switch but no help. I don't drive it much took it out two weeks ago in day light and the engine died three times. I did add a pertronix coil but still the same problem.

 

Start by cleaing up all the negative and postive cables, and the places they attach with some emery cloth. Then check you battery voltage at idle with accessories on. Should be about 13.6V or higher. Run the car at about 2K rpms and recheck battery voltage, should be about 14.6V-15V.

with ignition on, car not running, take your meter with the positive lead on the positive battery post and the negative lead on the positive post of the coil. Should be 3.5V or less. If greater than 3.5V you need to clean up the circuit that goes from the Positive of the battery through to the positive of the coil.

If you do a search on Pertronix you will find some very good information.

 

My charging system is find now, back in Feb. replace battery and alternator.Went through two alternators before I got a good one.

 

I just installed the ignitor 2 with the flamethrower 2. It helped out my performance alot, and i haven't had any problems....... yet.

 

I never have had any problem whatsoever out of my petronix. I have it in a 73 351C.

 

You're appearantly dropping below the minimum required voltage for the pertronix to work. That's why it will run with the lights off but not with them on. You have a problem with your car's charging system, not the ignition system. Have you had your regulator checked? Did you buy a good alternator instead of the cheapest rebuilt you could find?

 

After you have cleaned up all your ground connections, and you are getting the proper volage as was mentioned, then you are not getting at least 7.5 volts to the Pertronix. If you drop down several posts, you will see where we discussed that at length. Basically, the pertronix needs to be hooked up to a 12 volt switchable source.

 

yes, We discussed this alot. Go under the dash and splice into the ignition wire before the resistor wire connects to it. Mine was close to the swich. I dont if a 72 even has a resistor wire[&:]..........

 

So I need 12 volts to the coil ? By runing a new wire to the coil this will give the volts I need? I will try that and get back to you. Thanks so much.

 

Yes, but but you need a switched 12v to the Pertronix. Here is how I suggest you do it right.
http://va-mustang.com/articles.php?articleId=3