Just remove the lighter if necessary, and clean it out really good. CHECK with an ohmeter that it makes good contact when pushed in. That is, the hot terminal to the shell should show nearly a short.
Reinstall it, and do one of two things. If you have a tack run off points, or Mopar ECU, or GM HEI, just tie into the tach wire so that when you push in the lighter, it's grounded
If you have MSD, this won't work.
Another route is to use the lighter to ground one coil terminal of a relay, IE the relay must be active to start the car.
