My old lifters (stock hydraulic) have sat about 12 years so I figured I'd change them while I have the heads off. The new ones are also stock and I can compress them against the spring a little although I can't compress the old ones any. I assume they will pump up a after I run the motor. Is this right? I suppose when I set my adjustable roller rockers I'll have to be careful not to compress the springs in the lifters to get an accurate setting? It seems like I should be able to squeeze the oil out of the old ones. I have heard of anti-pump up lifters. I guess my question is how do hydraulic lifters work and is there anything wrong with my assumptions?
