308 ENGINE POPS AND CRACKS THRU EXHAUST

An intake vacuum leak will produce the symptoms you describe. It's a good first place to look.

 

Generally speaking, vacuum leaks, wrong mixture (like from a leaking injector or poorly tuned carb) and timing can create backfires at low rpms and under acceleration. When lifting off the throttle you backfire, then often it is an exhaust leak or a problem with emissions equipment. (I once had a Triumph TR7 that popped and I traced it to a bad valve in the air injector pump. I took off the 15-pound piece of junk and the car ran perfectly.

 

Have the mixture, carb synch and timing checked first.

Birdman

 

I had that and it turned out being bad spark plug wires. It was only noticable while sitting at a traffic light or similar low rpm. As soon as you began to pull away, it would smooth out. I replaced the wires and plugs, serviced the rotor caps and buttons. The snap crackle pop went away. I mean it was a very noticable improvement. J

 

Kind of hard to tell without knowing what car it is??