Hey I just went from NEW GUY to WRENCH FETCHER is this place COOL or what. I think doc41 may be on to something here. If the oil galleys are high in the block they may not align with the lifters correctly. I know that the lifter bores are the same ID as I have used roller cams in non roller blocks. What I don't know is if the bores are the same depth, roller lifters are taller hence the shorter push rods. If the oil galleys are not matching up or if the lifter is to low in the bore, oil could be passing the lifters and returning to the bottom end as the engine heats up and things expand. I know of a real good engine machinest I'll point the problem at him and see what he says.
