I've done it both ways. HKS step3's and JWT C1's. The cams made for solids have a small section before the lobe that takes up the gap/clearance first. The hydro lifter cams don't have this because they run 0 clearance normally. Hydro cams on solids is just a little noisier, but perfectly fine. I've known several other people who've done it as well. Step3's (solid cam) was actually pretty quiet as far as mechanical noise.