I got to thinking about adjusting the valve last on this engine to see if that helps with the noise. Problem is that I have never adjusted valve lash on factory rocker arms that are just stamped out pieces of steel.
I'm lost here. If you have hydraulic lifters and stock rockers....there is NO adjustment. If the lifters are clattering then you need longer pushrods. If the lifters are holding valves open, you need shorter pushrods. Better yet, if this is the case, maybe the heads need to come off and get the stem heights checked and see how far the heads have been decked.