Put my new motor in and fire it up to check for leaks, break in lifters, etc. Its a used comp cam with new comp lifters. I keep hearing a miss during all this and cant get steady vacuum. After it cools for a minute I run the valves again, #2 has a collapsed intake lifter. So I tighten it up and run it again with the adjuster sticking way out the bottom, a good .150 more than the others but at least the car moves which it needed to by monday. I decide to start doing compression checks. #1 has 150ish lbs so I have a baseline and go to #2, reads 0. #4 reads 150ish so I know im good there. Start pumping air into the cylinder to find out if the valves are actuating, I over tightened them a little to let them off the seat. I put the air on and can hear it leaking all over so I close exhaust then it pushes the piston to the bottom of the bore and all the pushrods jump. I go to close the intake and it seams to screw out quite a bit. Bam, the lifter had pumped up. I run the valves again, do a compression check, got 150ish lbs this time, fires right up, no misses, idles decent(my carb is crap). I just thought it was wierd out the air helped pump the lifter up. Anyone else experience something like this?