My 472 hemi is quiet upon start up, then when it reaches operating temp, the valvetrain (comp hyd 292) on all 8 cyls gets noisy (stethescope) and a couple (I think 4 and 7) are noisier than the rest. I fretted over the for a month- even posted a question on here about it and the general consensus was it is normal considering the odd pushrod angles etc..
No issues at all- to date