KABOOM! when hitting headlights.....

Took out duster this morning to go to remodel job I have been chipping away at. 12 miles one way. 72 /6 duster...stock... Dude was sleeping so I spared him the noise and chalked it up to having a cruise with little traffic. Back in car about 5 miles into trip home and under light load up an on ramp and I hit the headlights on.....sounded like a gunshot, very crisp. Lost power for a split second, hand was still on headlight switch so power off on switch, car regains power and Im off on highway and ran fine all the way home. left running in drive for visual inspection, nothing jumped out at me. turned on/off/on/off headlights with no symptoms.

1. There was a harder than normal start this morning, ususally a two pump and touch the ignition to start and goes right to high idle.

2. I have a small exhaust leak at manifold but only something heard under power...very small.

3. A year ago I drove it 40 miles to adjacent town and had the carb (1bbl) loosen up on me and got her tightened and then no prob.

4. It needs some adjustment as in drive idling it will have a slight miss or something every 3 sec or so. Seems timing related.

5. I have a lockout something or other disc with little square holes in it that I havent put in....just been driving it.

Where did the shot come from? I would assume through the exhaust but I have not heard any more of an exhaust leak, no hole in muffler.

Need to check plugs......but I thought Id be lazy and just ask you:rolleyes: