You’ve got questions. We’ve got the answers—the Summit Racing tech department tackles your automotive-related conundrums. This week, we’re tracking down some ignition box issues in a 1974 Plymouth Duster.
W.S. Vienna, IL
Q: Our 1974 Plymouth Duster has a 318 with an automatic transmission. The car is mechanically sound, but it will not run with the foreign-made ignition box I got from a local parts store. I’ve run tests, and even swapped out the ignition switch and steering column wiring harness, but the car still won’t fire up. The only way I can get it to run is with an original Mopar orange ignition box, which is probably discontinued by now. Please help; electrical problems always put me in full panic mode.
A: Good news: The orange Mopar ignition control unit is still available—part number 4120505. But before you order, check your distributor for excess play and test your charging system. It should be putting out 12 volts or more. Also, check the engine-to-frame ground, and make sure your coil does not have too much resistance. For added performance and reliability, you may want to step up to a Summit or MSD ignition control.