push rod help!!!

A thousandth of an inch won't make any difference. If all of the lifters are making the noise then it's likely the nature of the cam. If it's one or two then you could have a bad lifter even though it's new. If that's the case you could take the lifter apart and make sure it's clean inside.

The other thing to check is to make sure you don't have a rocker touching the spring retainer or a push rod hitting some casting flash in the head.

I have an XE268H that I get a fair amount of clatter at start-up but it quites down right away and then I get that noise that is described as a sewing machine all the time. Comp told me that was normal with the fast closing ramp on the extreme energy series of cams.