Originally Posted by LATECH
20 is pretty normal .
Not to sure timing would be the issue here. Did the symptom occur after a timing adjustment? Did anyone adjust the timing?
Sounds like air getting into the exhaust stream. Maybe the EGR valve is sticking?
Could be also the carb is too rich. Also faulty AIR check valves can let air into the exhaust when not wanted and cause a pop or a burble.
Well when I bought the car my buddy set the timing because it was running really rough. I didn't have a timing light so it was set by ear, and he put a chrome cover on of course.
I just noticed it now a few months after the timing was set, it sounds like a quiet pop or thump. No repetition or anything. I could only hear it when I'm by the exhaust and it kinda shakes the car. And I see a spike in the a/f when it happens, maby 16.0 max
I'm not sure what the AIR check valves are but I'll research it.
Theres a tube from my cat that comes up on the pass. side and it sucks, I'm not sure what that is.
We also replaced the huge stock air cleaner with a chrome one and removed the AIR tubes from the manifold
I have an a/f ratio gauge that's reading 14-15 so its not too rich
I'll check the egr valve, I didn't think of that.
Thanks for the reply