crf311

I just finished installing a set of dynomax headers,along with the chambered exhaust. Let me tell you this set up sounds great. But now I have a popping in the exhaust when I let up on the gas with the trans still in gear. It is not really a back fire but more of a pop, pop pop . It is also comming out of both side of the exhaust. It I push in the clutch and coast to a stop it will not do it. I kind of think it is running rich. I have checked the timing and it is ok. I have the complete MSD set up, (6al box, coil and tach).
So if you have any input as to what could be causing this I sure would like to hear from you. Thanks

:cheers:
Robert

trw

Sounds like it could be a little rich.

You tend to get the popping with a less restrictive exhaust also.

Hope this helps.

Terry

red79c3

I had a set of Hooker headers and sidepipes installed on my 79, she did the same thing. I went back to the shop that installed them (they also did a complete tune up at the same time). I was told that they mixed her a wee bit richer and thats most likely whats causing the popping noise...

cardo0

Depending on your cam a set of new headers may need a new advance curve as the heads breath better and a bit richer(?) at higher rpm. But if its poping on let-down, how's your vacuum advnce working? Maybe need some adjustment here (start more advance at lower vacuum) or change to manifold vacuum rather than ported vacuum. :skep:

LAvetteman

I had a problem with my 71 popping just off of heavy acceleration, it was more like a boom!!!(kinda like a potato shooter). You guessed it, I was running way rich. That was before Lars tuned my Demon via mail. :thumbs:

First79vette

Wow! :eek: Cant believe this I just brought my dynomax headers home tonight for my rebuild and I'm going to put chambered on too :D sound rich to me but would an H pipe help out?

munday

yeah i went through this all it was, was a fouled plug from..you guessed it...running to rich....clean your plugs with some wd-40 and maybe go to a hotter plug

comp

if the plug fouled replace them, ain't that much $$$ and you can get a better
plug reading from new one's :thumbs:

lostpatrolman

My friend has a 99 trans am with ram air. Put some borla catbacks on and when he lets off the gas in gear he gets a burbling/popping sound.

PRNDL

Robert, The popping you describe is typically caused by an exhaust leak. You just installed the headers and exhaust - Is it clamped? Somewhere along the line you have a leak. Try tightening everything up. I got the same popping when I had a broken front exhaust pipe, and the same popping when I installed a new exhaust system with lots of clamped connections that leaked a bit.

When you add headers you improve the flow. Doesn't that tend to lean out the mixture, rather than richen things??? More gas out the exhaust means more air gets sucked in the carb. Same gas, more air = leaner.... right? When I added headers I was concerned that the engine would run too lean so I jetted the carb richer at the same time.