Cylinder Misfire after head rebuild?

[jgf100]

I recently had my 302 heads rebuilt, have an edelbrock rpm performer intake, holley 600cfm carburator and new Pertranox distributor. Now, there is a bit of a rough idle, using the timing light and tach, rpms tend to jump up and down ever so often. You can actually feel the drop on the body of the truck. I'm guessing it's a cylinder and or rocker issue due to heads being rebuilt. Is there a way to confirm what cylinder is the issue, and or is there something else I need to look at?

Thanks!

[davelj]

Have you checked the vacuum? You might just have a vacuum leak somewhere.

[jgf100]

Have you checked the vacuum? You might just have a vacuum leak somewhere.

I have checked the with a vacuum gauge, no leaks detected. I also took it to a carb shop to tune the carb and although I didn't ask them to check, they didn't mention a vacuum issue.

[basketcase0302]

="davelj"Have you checked the vacuum? You might just have a vacuum leak somewhere.

Just from your description.
Take a can of starting fluid, (I use it because it leaves no residue and gives a split second result) and spray all around the intake. Pay particular attention to the end rails as that's a common place for vacuum leaks, (especially if the old skool cork end rail gasket was used, (most all of us now run a nice bead of silicone RTV sealant there). Also recheck your head torque, (most all head gaskets spec this after a few hours of run time) as that's another place for a vacuum leak due to the work being done.