chevy sb engine clatter

I just installed a new Comp cam,lifters,valve springs,push rods,seals and roller rockers in my 86 trans am with a 350 small block chevy,but can not get any adjustments I make to stop the clatter (like a diesel) all I have managed to get by over tightening the rockers are bent rods.Any help on what might be the fix would be great!!

First, it would help to give some specs on the cam and springs used as well as the length of the pushrods. Is it a roller cam and kit designed for the L98? It sounds like you have mismatched parts!

Cam used is the Comp cam #268H along with the required springs #981-16, push rods #7812-16,also used required lifters-locks & retainers that came with kit.I Do not know exact year of small block 350 since it is not the stock engine,it was swapped out years earlier but believe year to be mid to upper 80's.Basically wanted a bigger cam & used a Comp cam kit that I thought would be workable.

I would say that maybe the lifters are shot, maybe.