a buddys 97Z M6 with cc 305 with ported and milled heads, stock valves, LT's, no tune, LT4 km, 1.5:1 rockers, K-motion 800 springs, k-motion valve locks, k-motion retainers, crane lifters.

knocks all the time even when car is warm, killed cylinders (pulled wires, and injectors,) and noise still there it seems to be a valvetrain problem.. falls on it face after 3500 rpms cannot figure out whats wrong with this car.. can anyone help we need ideas on what else to look for.. thanks for the help.

 

What pushrods are in the car? I had a similar problem and it was that one of my hardened pushrods broke in half and the bottom half of the pushrod was jumping around in the lifter valley... which caused a lot more problems.



MY suggestion is to pull the valvecovers and just take a look around.

 

there stock pushrods, he has taken them out to change to the crane lifters and says there straight and nothing is wrong with them.

 

YOu might want to suggest that he changes them out anyways, 'cause if they are not already broken they will be at some point. Stock on a '97 are 3-piece and non-hardened.

 

will do boss thanks, any other ideas?

 

Also the rockers might be too tight. That's what happened to mine, somehow the driverside tightened them selvs down causing bent and broken pushrods.

 

After seeing '94 Bad A Z28's pushrods, I'd recommend changing them any time a new cam/rockers are put in.