this thread got me motivated to do something that i have been wanting to do for years but just couldn't seem to find the time---------to date i have probably built nearly 40 turbo engines over a period of 15 years-------lifter preload is never mentioned in any GM literature (at least none that i can find) and I have always done things according to what others experienced builders have suggested---------for numerous engines i have used the range of .030 to .040 and it has always seemed to work fine--------but i have always wondered what GM did originally in our engines-------today i took one of the brand new crate long blocks that i have and checked the lifter preload-------it was a 0 mile engine assembled in oct 86-------very surprising results---------i checked one bank only-------driver side-----here is what i found---------pushrod lenghts were 8.677, 8.676, 8.672, 8.674, 8.671, 8.672 respectively------- i have normally considered that the median length of turbo pushrods to be 8.680 based on previous measurements of numerous engines-------i have removed them from used stock engines a long as 8.684--------i only checked the preload of lifters 1 3 4 & 5 since lifters 2 & 6 were sitting on the high side of a cam lobe and i didn't want to rotate a brand new 20 year old engine without doing some lubrication prep---------preload was .096, .078, .079, .093----------quite a surprise------a lot more than I expected but it appears that is how they were set up when new-------when I get another chance I intend to check a couple more engines to see what the overall variation is----------i also checked the plunger movement range in the lifter-------.196---------seems that GM chose to set preload just about midrange of the plunger travel--------that would allow for the greatest service life due to part wear since some wear surfaces increase preload and others decrease it........................RC