With as good a valve train as you can get these days, I don't see the advantage of hydraulic roller lifters. You can set a solid roller and forget it for the season in most cases. BUT...if you're comitted to hydraulics, I'd call Comp and ask them about this. I know in most cases, manufacturers will tell you not to pre fill hydraulic lifters, (soak in oil) but to let them fill on their own with engine oil pressure. It's easier for a lifter to pump up a little, than it is for it to bleed down, and risk tagging a piston with a valve untill it does so. That dosen't sound like your problem, though.