383- passenger side rear ewxhaust "popping" sound- where to start looking for th

[skingjack]

Brought the car out of hibernation; some engine upgrades were performed over the winter (cam, timing chain, lifters, springs.valve seals) to make the car more enjoyable. Unfortunately, I now have random popping/farting noises coming out of the passenger side tailpipe only which never presented themselves with the previous cam/springs. Popping noise seems to present itself when mostly at idle or decelerating. Just curious if any one might be familiar with a similar popping noise and point me in the right direction as to where to start looking for the cause ( valves, exhaust leak, bottom end etc.). Unfortunately I cannot add a small video due to size/ forum constraints; I'll see if I can come up with another to way to make the video accessible later this morning.

Any thoughts muchly appreciated.

Ian

[XH29N0G]

For what its worth.  It can be possible to make a video link and then post that.  I forget how I did that (too old....my teenage son helped), but I know it is possible.

I am not the one to answer your question, I would wonder if it is fuel getting by and popping in the exhaust or something else?  Others on here will know more.

[Alaskan_TA]

If the manifold heat control valve is still present, check to see if one spring or both have failed or disappeared.

The flapper inside can also come loose from the shaft, so you may have to check for that also.

[BLK 68 R/T]

Did you verify spark plug wires are all on fully and in the correct firing order? Also was the timing adjusted for the new cam?

[skingjack]

link to the video... hope this works



https://www.dropbox.com/s/qf8m0hegmll3ctw/IMG_6984.MOV?dl=0

[Chargen69]

well...  that's interesting

[XH29N0G]

I also don't have an answer to the popping in your video, but I suspect someone here will have an answer and help you get this sorted. 

The thoughts I have are (1) that the frequency is less than the firing (so it does not correspond with every single firing of a cylinder), but this doesn't mean it isn't cylinder specific.  (2) I would probably try to localize the sound using a mechanics stethoscope or something else I could 'hear' with like a long screw driver or metal rod placed between the bond in front of my ear and against the head or exhaust manifold/header.  I might also try a long tube with the same principle.  That might help figure out where it was.  I suspect it is related to a cylinder and valve, but really do not have the expertise to make that call.  See whether others here have a different opinion and believe them over me.

Good luck with this. 

[BLK 68 R/T]

Sounds like a spark plug not firing the cylinder and then the gas is igniting in the pipe to me.

[John_Kunkel]

I would take it to somebody who has a scope, probably cheaper than "shot gunning" suspected parts.

[69Chrgr]

My solid roller 512 does that when it's cold, stops after it warms up.