i bought a new engine from gm. it was the caprice tbi roller engine. put it in my 89 z tpi. i put a comp cam with the specs: 206/212 dur. 480/488 lift. ialso bought EVERYTHING new. including new delco ecm,chip, sensors,distributor. you name it, its new. we didnt degree the cam because kinda pressed for time. this thing has valve clatter like crazy. it does especially bad when shifting at full throttle from1-2. when the rpm falls between shifts ,thats when it clatters the worst. i have a hypertech chip from way back. i switched the delco prom to the hypertech and the clatter is less but it still there. i know its killing my power and my engine. with my scanner my timing gets retarded as much as 15* at full throttle. it may be more. its been so long since ive looked at it. i got so sick of working on that POS i parked it. been at least 6 months. im thinking about trying to get it cranked and maybe work on it again. maybe. i need some help pleeeease. do i need to degree my cam, have a chip burnt, or what? anyone?

 

did you lash the valves with the engine running?

 

yes

 

try more octane or less timing

 

It's not "valve clatter". It has nothing to do with the valves. It's spark knock, caused by the fuel exploding instead of burning smoothly. The usual reason is that the ignition timing is too far advanced for the quality of fuel you're using.

Back the timing off a little at a time until it quits. If the motor still seems to run right but the timing mark says the timing is way off, then the problem is probably that the timing mark is wrong, not that the timing itself is wrong. Either you replaced the timing cover with one that has the mark in a different place, or your harmonic balancer's inertia ring has slipped.

It's not the cam. Leave that alone.