I had all new lifters and now a few of them compress completely by hand. I do have dual valve springs with an aftermarket cam regrind that gives more lift and duration. I imagine factory lifters are typically a weak point in a built valve train. It is possible that they were bad from the factory but they didnt compress by hand when i installed them. Would factory lifters from the b2200 head possibly be an upgrade? Anybody know if the lifters are any different between the dual valve spring 8v head in the b2200 vs the n/a 12v head on a 1g mx6? Its probably not safe to run the engine much with a couple bad lifters what do you guys think?