Backfiring on deacceleration..normal for our sidepipes

[mbeers6]

Hey guys,

So I've always had some backfiring/popping on deacceleration, but now curious if it is normal for the B&B sidepipes or do I have a problem.

I have the ceramic coated B&B side pipes which appear to have just glasspacks for mufflers, they have about 5k miles on them.

I've checked all header to cylinder head cylinder bolts for tightness and leaks, seems okay. Used high temp RTV on header to sidepipe connection, no leaks there either.

Also tried richening the idle mixture screws which helped a little.

Its a mild 351w running 650 eddy carn and about 14 degrees initial advance (petronix vacuum advance distributor).

Any thoughts? Do your guys pipes crackle and pop on deacceleration?

Thanks

[Wbulk]

Have you had your air/fuel ratio checked. Too rich a mixture will allow unfurned fuel to ignite in the exhaust, especially with a large overlap cam. That popular loping sound is less than ideal combustion making it's way out the exhaust.

[Tommy]

The odds are very high that you have an exhaust leak. When air gets in with unburned fuel in the exhaust, it will pop. Check for leaks where the exhaust manifold meets the engine and where the manifold collector connects to the side exhaust.

[davecobra]

Air is getting in the exhaust system someplace, warped header flange on the head, warped flange where the headers and pipes fit together or a crack in the pipes someplace.
You may not hear the leak but on deceleration it will suck air in and cause combustion in the pipe which is the popping you hear.
David

[mbeers6]

Thanks for the replies guys. I resealed the header collector to sidepipe connection and next is replacing the header to cylinder head gasket.

Any problems with using a copper gasket AND high temp RTV? I thik I would put the RTV on both sides of the gasket.

[Buzz]

I actually like a bit of crackling and popping on decelleration. All the better for terrorizing local villagers and setting off the alarms on their bimmers.

[lamaluv]

Me too Buzz, though you do have to watch yourself if your cruising through the hood. If they think your shooting, a gun battle can very easily be started.
Dick

[Buzz]

Well I haven't received any return fire yet - at least none that I've noticed. Maybe the perps are too busy ducking and covering when I do my drive by.

[lnfletcher]

Mine does it and is caused by a leak in the header to sidepipe area. I corrected my rich condition with a new carb and it lessened it greatly. Now it only does it when hard engine braking in cooler weather.

[Dwight]

Any problems with using a copper gasket AND high temp RTV? I thik I would put the RTV on both sides of the gasket. 

I tried the copper gaskets, worthless junk. They leak. They leak everywhere. The Red High Temp RTV will melt and run out. Big mess to clean up.

The best thing we have found is Percy's laminated aluminum header gasket found at the local parts stores (O'Reilly) and Summit / Jegs. Cost about $31 pr. If your header flange is warped, you can use one and half on each side to seal. They are the best header gaskets we have tried. You do not need any RTV seal and use can re-use them.

Dwight

[Sal Gerace]

Remflex are the best gaskets you will ever buy. They are thick are very heat resistant and conform to any imperfections or mis alignments. No silicone needed. I had the backfire on deceleration issue and these are by far the best, although a little pricy, but well worth it.