OK, I just accessed the comp catalog lifter section. For their Hi-Tech series of hyd lifters they recommend a preload of .030 to .060, for their Race series of hyd lifters they recommend a preload range of .000 to .030. For their retro hyd roller lifters which I have, they don't make a recommendation . I'll check with their tech line tomorrow. Has anyone else actually used these guys yet or have some info on what the preload on these should be?