I`ve seen, and had hyd. roller cams that were louder than solid roller cams. the last being compcams in a hot 406 sbc. back then I talked to a chevy racer and mech. that has held an NHRA record 18 times over the yrs., and he said a lot of them do that. if everything is right in the valve train, I wouldn`t worry too much about it . you might try tightening the preload a little more, try one full turn. I did and it helped some. -----jfyi