Or maybe just more noticeable at low RPM? You have to kind of strain a little to hear it, I've not heard anything quite like it before, but then again I don't tune cars every day.

Brand new engine, just broke it in. This is my first time. Timing is at 12 BTDC and seems steady. It revs fine and does not surge or anything. Idle needs to be near 900rpm or it loads up. 350 SBC with a CC 268XE.

Checked all wires and plugs, but I can't tell if the vacuum advance is working properly. I can disconnect the rubber hose from the distributor and it doesn't really seem to change idle characteristics all too much. I don't know which to plug it into on the front of the carb either, right or left? (Edelbrock 600cfm) I tried both and it didn't change the miss.

Another thing that doesn't seem to change idle all too much, is the 2 carb screws up front. Shouldn't you be able to get the car to stall with them? I can only slightly change idle with them. The carb has been sitting a long while and backfired a lot when first firing up the engine. Could the carb be a contributing factor?

I also have a huge exhaust leak at header to block, pass. side cylinders 4 & 6. Hopefully this will be taken care of tomorrow.

Any ideas on what to look at or try next? I just hope it's nothing serious and can be tuned out. Thanks guys.

Brian

What type of ignition system? If it's still a points ignition, it may be time for a new set, or better yet, time to upgrade to electronic.

The vacuum hose on the distributor is probably plugged into ported vacuum.

Now to address the problem. It could be a small vacuum leak, or a rocker that's a little too tight. Check for vacuum leaks first. Before pulling the covers, did you set the rockers, and how far down did you adjust them?

It's a GM HEI with a slightly hotter coil under the cap. Before the engine blew, I cleaned it and changed out the coil, cap, and rotor, along with the plugs and wires. Ran for one day. I have an MSD 6A but don't have the right timing light so I didn't install it.

I adjusted the rockers loose for break-in. I've only done this once so pardon the explaination: Just when I found the point that the pushrod had a little drag on the rocker, I tightened down another quarter turn. After a 15-minute break-in, in which the car almost overheated, I tightened them again about a quarter. I didn't have any guidelines so I hope that is close to being right?

I'll check for vacuum leaks. I'm using a carb spacer on a performer mani, so maybe it's around there?

I'm desperately hoping my cam is ok.

Brian

1/2 turn sounds okay. A vacuum leak check is next. Do a compression check if that doesn't turn up anything.