67 273 Stop Running

All

Driving to our car club tonight, my 64 Valiant with a 67 273 4 barrel 4 speed transmission just stopped running. My wife was driving and I was right behind her. She said she heard and felt a pop thru the gas pedal and the engine just stopped running. She coasted it to the side of the road and we had it flatbed ed back to the house. It's been running great for a year or so. I have electronic ignition and a new 650 sitting on the motor. I swap out the ballasts with no results.

Bearwolf64