I have been having a problem with my car making a popping sound when the engine turns around 4500 RPMs. I called up my mechanic and he said that it might be a worn lobe on the cam that isn't opening an exhaust valve all the way. He said 80s chevy engines are known to do this. Does this sound like it could be my problem?

 

might be, might not, you'd have to trouble shoot it a bit to know for sure

 

Any suggestions on how I can troubleshoot this problem?

 

Take the valve covers off and make sure none of the rockers are loose. If any are, make sure the rocker studs aren't pulling out and the rocker nuts aren't backing off. If those are ok, pull the intake and take the lifters out and check them for wear.

 

Checked the rockers: they're all connected correctly. I fired the engine up with the valve covers off and the exhaust valve on the #3 cylinder is not opening as well as the other ones. I haven't had time to pull the intake off yet.

 

If you're lucky, it could just be a bad lifter. You'll have to take the intake off to find out either way.