Popping through the mufflers

[44070dart]

My cousin has a 340 six pack/4 speed Dart. The car > occasionally < pops through the mufflers. Small pop, nothing big, sometimes cold, sometimes warm. Runs fine, plugs looked good, he put new ones in, with new cap and wires. PerTronix ignitor system. Other than this, car runs fine. Choke works properly. ??

 

[George Jets]

His exhaust system has a leak in it allowing oxygen in, to ignite unburned fuel.

Headers are a source of leaks.

☆☆☆☆☆

 

[44070dart]

I think he has a header gasket leak. I need to ask him. Thanks

 

[MopaR&D]

I've had issues with the Ignitor systems being faulty, specifically the Ignitor II. And it's not a "works fine or doesn't work at all" like they claim, mine had occasional misfires and when the RPM got below a certain point (low idle, like when cold) it misfired like crazy and barely ran. Swapped to an Ignitor I and it fixed the problem.

 

[44070dart]

Why wouldn't it happen all the time if gasket leak. He asked, I have no answer.

 

[MopaR&D]

Why wouldn't it happen all the time if gasket leak. He asked, I have no answer.

I imagine it would happen all the time, or at least it wouldn't be a single random pop except maybe when snapping the throttle shut. I think it would also make a constant ticking noise similar to valvetrain noise.

 

[Inertia]

Why wouldn't it happen all the time if gasket leak. He asked, I have no answer .

The system needs to suck in oxygen to be able to burn/pop.
To get negative pressure in the exhaust needs deceleration to suck in air .
Have someone plug the tailpipes with cloths while it's running, and listen for leaks, ( the cloths will get very hot quickly, so be quick ).
Repair the leaks, the "pops" should disappear.
Cheers .

 

[44070dart]

Yeah, I remember now hearing the header gasket leak when we first saw the car, because at first I thought it was a lifter clacking. I'll see him this weekend and see about replacing the gasket and see if it stops popping. I agree that will be the fix.