Marc80

I suspect this is caused by valves sticking a bit after being parked at the body shop for months on end. One time they had it for a month and then it ran rough (popping) and they checked the timing right in the parking lot. It didn't help, but as soon as I left it disappeared. Now that it has been parked allot and only started to move a few feet in their lot I have heard it is running that way again.

Is this something to worry about? Any way to prevent it?

The engine is still in breakin and has been only driven fairly gently so far.
It has a moderate cam, contributing most of the increase in HP. Also Lunati roller rockers, headers and true dual exhaust (I may add crosspipe to lessen standard popping but this problem is more like "valve stuck open a bit" and not like the rumbling pop that the car typically makes.)

Steve Grodin

I had a similar problem with my car after picking it up from the body shop several years ago. Turns out they were starting it and moving it a few feet every day and fouled the plugs. Changed them and all was well.

Metal Wulf

when my exhaust was popping, it was due to a plug wire in the wrong spot. pull the plugs on each cylinder one at a time and see if the popping stops.

logans73

My 73 does this after sitting. I was told it was carbon buildup (valves, plugs, etc). The solution I was given was to drive at highway speeds (higher RPM) for a extended period. If I was unable to do that, I was told to shift into 1 or 2 and just hold a higher RPM. It also goes away if I drive for awhile. Good luck.

Jon

Marc80

Come to think of it, they did suspect the plug order when it happened the first time. But with all the complications we had getting the motor running right the first time, I knew we were meticulous about the firing order and no way we mixed it up. That it would be fouled plugs makes sense.

In the process of trying to get the car running right the first time we fouled a set of platinum plugs so quickly it took us a long time to figure it out. We swaped out for some cheapo plugs and it ran great. The bad plugs were passing the spark across the ceramic and not even jumping a spark across the gap. I couldn't believe it. I got myself a new carb (Holley street avenger 770cfm, I think) in the process, also MSN distributor. turned out that much of the problem was the plugs. I was OK with the new parts anyway since they went on a new motor.

I suspect I could prevent this problem by just using as a good occasion to change the plugs....or just burn them off. Last time it only took a couple of blocks. I am just paranoid of every odd sound with this new engine ...and new corvette for that matter. I drive and listen ...you know how it is I am sure.