Thanks to all the techies and moderators like Bill who take the time to respond to our questions and impart their vast knowledge and experience on our behalf. Thanks Guys!!!! Now for next stumper. Having just rebuilt a 350 I prpepped for initila startup by first prelubing and presetting the valves (hyd). Started right up but the valves clattered (all) and would not quiet down. Radjusted with engine off 3 times with no improvement. Adjusted twice while running again no change. Checked pushrods for length and rocker arms, both are correct. By turning the adj nut in 1/8 turn increments I was able to completely bottom the nut on the stud and the valves still clattered. Engine ran fine. Everything is oiling fine through the pushrod. The lifters came as part of a shortblock kit and I assumed they were correct as they were the correct diameter. The oil groove must also be ok as they oil prpperly so I am stumped. Could I have been slipped some Rhoades Lifters by mistake as they all clatter like solids? Or are they the wrong ones (maybe pontiac)? And I am positive they are hydraulic lifters no matter which ones they are. Anybody have any ideas? All I can think to do is pulll them and compare with what I know is correct.