Fao Danny Hydraulic Lifter question
 

I got given a set of working lifters in a pot of oil for the det last night with a replacement head. I still have my old head etc but a few lifters where starting to play up. Ive read on sxoc DONT MIX THEM UP OUT OF ORDER lol. Why is this?.Are they shimmed or something? I am going to overhaul them as much as possable, Do they mean dont mix the dissassembled lifters with each other (which makes sence) or do they mean dont mix lifter from no.4 up with lifter from no.1

some people (a minority) think they are specific to the hole they come from like a bearing. I've changed lifters individually and as sets and I've never once had a problem from moving them around, and I'm talking about a lot of engines.

thanks, thats all i needed to know