all of My rockers on my 454 BBC are a little loose, I can spin the pushrods with my fingers and jiggle the actual rockers a little bit. It has a hydraulic cam and lifters. I would have never thought about it but it seems that one of the rockers was hitting the valve cover and actually cracked it which made it start leaking oil. I never heard any clattering of any kind but then again this is in a jet boat with open headers. What do you guys think? How tight should they be?