Q: I have a 1968 Camaro with a 396 engine that’s .030″ over and has a port-matched Edelbrock Air-Gap intake manifold, 750 cfm carburetor, and an MSD 6AL ignition control, Pro-Billet distributor, and Blaster coil.

I recently installed new lifters, rocker arms, and a COMP Cams 268H cam. The engine runs strong right up to 5,500 rpm and then begins to misfire. It would wind up to 7,000 rpm with the old flat tappet cam without any problem.

I’ve installed new ACCEL 9000 ignition wires, changed the distributor weights and springs, and checked the timing, and it still misfires at 5,500.

Is it possible the ignition control, coil, or distributor when bad during the cam change? Or even worse, could the new cam be the cause of the problem? Please help!

A: While your COMP Cams 268H cam stops making power at 5,500 rpm, it shouldn’t cause a misfire at higher rpm. It should just stop pulling. We like to check easy things first, so make sure your MSD 6AL ignition control is getting a full 12 volts. Your battery could be weak and that could be the cause of your problem.

Next, we’d suggest checking your fuel line for kink or flat spots. We’ve seen fuel lines become damaged when cars are lifted for service.

Finally, check your valvetrain. Make sure your valve springs aren’t binding, that your pushrods are the correct length, and that your rocker arms are the correct ratio (they should be 1.7).

Hopefully, one of these suggestions will correct your problem and have your ’68 spinning happily over 5,500 rpm once again.