Popping in exhuast during idle and driving the car

[T toney]

I have a 67 camaro with a 396 with about 2500 miles on it and about 500hp, 780 Holley, 3" exhaust, the car came from an elevation of about 500', and now resides in an area of about 4000'. I recently tightened up the gas pedal linkage which was really sloppy, and after that I started getting some popping at idle and while driving. No jets have been changed yet for the higher elevation. Also, the issue has also appeared in the last month or so when the outside air temps have usually been around freezing or even below, one mechanic that it could be the really cold air.

I have a couple of quistions: 1. is the car safe to drive with this issue, and 2. What are the potential causes, and 3. what are the possible solutions.


Thanks.

[Josh]

Single or duel plane intake? Any smoke? General idea on what cam?

Could be incomplete combustion and fuel entering into the headers and igniting. It this were the case you would want to make sure your needle and seat were not leaking putting extra fuel into chamber, or perhaps you need a different plugs.

Lets here some ideas!

[anthonys 69]

The first thing id do is check to see the air fuel ratio at idle.
To check you can worm the motor up. You can closes the chock or close off the air coming into the carb very slowly [this is making the engine richer] until the motor changes in pitch or rhythm. If rpm increases you’re running lean if motor stumble that’s good. Then disconnect the smallest engine vacuum line you can [this making the engine run lean] if rpm increases your running lean if it stumbles that’s good. The next thing I would do is check engine vacuum with a vacuum gauge. You need a good steady vacuum.

[T toney]

Thanks for the responses guys, I think we most of the issue solved. I think the majority of the issue was altitude sickness and a pourly adjusted carb. After we got this adjusted better it was still doing popping a bit for about the first 20 miles after the adjustments, we attributed that to the amount of excessive fuel that had coated the headers and exhaust. After driving it for about 60 miles last weekend the problem seems to be resolved. We still think their is more power that we can squeeze out of the engine with a new accelerator pump, possibly different jets, and a few other minor tweeks. I excited to get those done so we can see what we got out of the 434ci, (396 stroked). Thanks again.