popping out exhaust on decel

Posted By: sixpackgut

popping out exhaust on decel - 11/25/11 11:00 PM

what causes it? could it just be my stupid staight pipe extremely loud exhaust? engine didnt do it in the challenger but that car had H pipe and full exhaust

Posted By: a493demon

Re: popping out exhaust on decel - 11/25/11 11:07 PM

exhaust leak could do that. brad

Posted By: BLONDE BARRACUDA

Re: popping out exhaust on decel - 11/25/11 11:41 PM

I had a header gasket do that

Posted By: Anonymous

Re: popping out exhaust on decel - 11/26/11 12:03 AM

It is from a header leak. either at the flange or at your collector merger.Chek your header bolts or youll need to change your gasket or just run straight hi-temp silicone of the flange to head.

Posted By: Guitar Jones

Re: popping out exhaust on decel - 11/26/11 01:56 AM

It could also be lean. Going from a full exhaust to open exhaust you'll need to richen it up.

Posted By: Anonymous

Re: popping out exhaust on decel - 11/26/11 02:55 AM

Quote:

It could also be lean. Going from a full exhaust to open exhaust you'll need to richen it up.

Not on decel only on accel.

Posted By: Ari440

Re: popping out exhaust on decel - 11/26/11 03:01 AM

check valve lash

Posted By: sixpackgut

Re: popping out exhaust on decel - 11/26/11 03:06 AM

Quote:

It could also be lean. Going from a full exhaust to open exhaust you'll need to richen it up.

i was thinking it was rich so i jetted down the center carb. didnt make a difference.

i havent noticed any exhaust leaks. may need to put washers under the header bolts, they may be bottoming out

Posted By: emarine01

Re: popping out exhaust on decel - 11/26/11 03:23 AM

A cam with a lot of overlap & a short header

Posted By: Anonymous

Re: popping out exhaust on decel - 11/26/11 03:44 AM

If you were lean,you'd pop out the carb not exhaust.

Posted By: Guitar Jones

Re: popping out exhaust on decel - 11/26/11 12:46 PM

Not necessarily so. It could be real close. I know it doesn't seem like that but with the rpm's up there and the throttle closed they go lean pretty quickly. Fatten it up from where it was originally and see if that doesn't take care of it.

Posted By: slippery440

Re: popping out exhaust on decel - 11/26/11 02:17 PM

Quote:

exhaust leak could do that. brad

Cracked header tube or gasket. Believe me just alittle crack is enough to make the popping noise.

Posted By: dvw

Re: popping out exhaust on decel - 11/26/11 03:21 PM

Quote:

Not necessarily so. It could be real close. I know it doesn't seem like that but with the rpm's up there and the throttle closed they go lean pretty quickly. Fatten it up from where it was originally and see if that doesn't take care of it.

Popping in the exhaust is from fuel igniting in the exhaust system. Briggs and Straton goes so far as to electrically close the main jet on shut-off to prevent backfire in the exhaust on shut-down. Eliminate any air leaks in the exhaust system and eliminate as much fuel as possible. If it doesn't have oxygen and fuel it won't ignite.
Doug

Posted By: Guitar Jones

Re: popping out exhaust on decel - 11/26/11 03:42 PM

Yeah when you shut it off, not just on deccel. Been there done that, take it or leave it. Not looking to argue with anyone, just stating my experience, YMMV.

Posted By: Big B

Re: popping out exhaust on decel - 11/26/11 03:50 PM

Quote:

Quote:

Not necessarily so. It could be real close. I know it doesn't seem like that but with the rpm's up there and the throttle closed they go lean pretty quickly. Fatten it up from where it was originally and see if that doesn't take care of it.

Popping in the exhaust is from fuel igniting in the exhaust system. Briggs and Straton goes so far as to electrically close the main jet on shut-off to prevent backfire in the exhaust on shut-down. Eliminate any air leaks in the exhaust system and eliminate as much fuel as possible. If it doesn't have oxygen and fuel it won't ignite.
Doug

I had the same problem. I leaned out my carb and blocked off my intermediate circuit, and all the popping went away. The popping is from unburnt fuel in the exhaust igniting.

Posted By: ToddP

Re: popping out exhaust on decel - 11/26/11 04:31 PM

Two things or both come to mind.

1. exhaust leak... fresh oxygen mixing with unburnt fuel.

2. Rich idle/ transition circuit...When throttle plates are slamed closed, engine braking occurs. very high intake vaccuum.lots of fuel pulled from idle circuit. not much oxygen however.

this creates a very rich afr. may not fully burn in combustion chamber. unburnt fuel enters exhaust. Too much unburnt fuel can ignite on hot parts of exhaust system. add oxygen from leak and eaiser to ignite.

Posted By: RemCharger

Re: popping out exhaust on decel - 11/26/11 08:05 PM

Last season my car was pretty bad, which wasn't an issue for me,,, but I changed carbs and it was done.
Usually its an exhaust hole.

Posted By: Challenger 1

Re: popping out exhaust on decel - 11/27/11 03:09 PM

I'm guessing your car does not have power brakes?

Posted By: sixpackgut

Re: popping out exhaust on decel - 11/27/11 05:36 PM

Quote:

I'm guessing your car does not have power brakes?

no why?

i found a couple header bolts a little loose. i need to bump the jet back up on the center carb. another thing is i never really drove around with the bug catcher on the motor in the challenger. so if i'm goin 100mph and let off, there could be alot of air doing weird stuff in there

Posted By: Challenger 1

Re: popping out exhaust on decel - 11/27/11 06:47 PM

Quote:

Quote:

I'm guessing your car does not have power brakes?

no why?

i found a couple header bolts a little loose. i need to bump the jet back up on the center carb. another thing is i never really drove around with the bug catcher on the motor in the challenger. so if i'm goin 100mph and let off, there could be alot of air doing weird stuff in there

My 74 started popping on decell earlier this summer, the power brake booster was leaking. Also caused a erratic idle. Replaced it and all is normal again on decell.