When you are tightening the rocker bolt, do it slowly, and you will notice at one point the slack is taken up on the valve side, and if you continue to tighten it the pushrod side will go down. This movement of the pushrod side is loading the lifter.

 

so at the point where it starts pre loading the lifter is when you stop? or torque it down to 27 ft. lbs and have just a slight pre load when doing so?

 

Ignore the torque spec for a minute, do it with a small wrench so you can feel when it tightens up. You want to start with the rod too short then extend it and retightening until you feel it start to compress the liter before the rocker bolt snugs up. You are trying to find the distance before you compress the lifter at all.

 

ok. so this is what i came up with..factory pushrod is 7.375..thats 10 3/4 turns on the gauge..i started at 8 turns and got it up to 10 turns.and it very slightly pushed down the lifter before snugging down. 10x.050=.500, then 6.8+.500=7.300, so id need a 7.300 push rod? also, i have the ls7 lifters and running 243's milled .025'' with stock thickness 6.0 headgaskets, which are .51'' thick...is 7.300 in the ballpark??

 

btw, thanks to everyone giving me a hand with this. greatly apperciated.

 

Try to find within a quarter turn of where it snugs up. Then add whatever preload you want to that number and try and find the closest pushrod to that final length.

 

awesome. thanks for the help. i triple checked everything and came up with 7.325 push rods. looks like we got my push rods tooking care of. appericate the help guys!

 

last question..if i measured 7.325, could i run 7.350 pushrods?? ive read were its possible to run a little more pre-load on the ls7 lifters.

 

Most guys aim for 0.075" preload, but people have done 0.050" to 0.1" without issues. Too little or too much and youll have a lot of valvetrain noise.

 

i didnt preload them a hole bunch..i might go with 7.35's and see how they do.