I have a 1996 GT with a 1997 block and PI heads. I have been running the Comp Xtreme energy cams XE-262AH (comp part #102500) for quite some time with no problems. I just swapped them for the XE-270AH (comp part #102600) cams and as soon as I started it up, my motor sounded like a diesel. I couldn't pinpoint it the noise, it wass all over the engine. After driving a few blocks, I decided to put the old cams back in (8 hours later) and had a new noise, sort of like an exhaust leak. I reved the engine to 3-4 grand and POP! TACK, TACK, TACK, TACK every revolution. Sounded like a midget with a sledge hammer in my block. I think I had a valve clearance problem. Any suggestions?

 

You have PTV...Piston To Valve contact...when installing cams on a 2V you must degree them in or else you can have PTV. You got lucky with the 262ah's but they are more mild, when going to 270ah's degreeing is a must. You probably now have bent valves and lots of issues.

 

Thanks. Any good links on how to degree cams? What could be some of these other "issues" as well as bent valves. I've already accepted the fact that I need new valves. Would different pistons help?

 

+1 Your gonna need new valves.