Originally Posted by
badass88gt
When you are measuring for length you want zero lash. You will adjust your amount of lash with the rocker adjustment during final valvetrain setup. Install your solid lifter into a bore and set your adj pushrod to around stock length.
Make sure your solid lifter is riding on the base of the cam lobe (zero lift).
Color the valve tip with some black ink.
Put your rocker in place and adjust it so that there is zero movement of the pushrod between the solid lifter and the rockers cup.
Rotate engine clockwise until you've achieved one full lift cycle on that valve. I usually do two engine rotations.
Loosen rocker and inspect the mark that the roller tip of the rocker has left on the ink covered valve tip.
You want the pattern on the valve tip to be centered on the valve tip. If the pattern is up high, towards the lifter valley then you need a longer pushrod, if it's low towards the header then you need a shorter pushrod. Keep adjusting your pushrod until you get the mark/pattern dead center and as narrow as possible. Measure your adj pushrod and order that size or as close to it as possible. (Trickflow's are a great deal). You also want the sweep mark to be as narrow as possible. If it is a little off center but that is where it gives the shortest sweep, use that.
Also be sure to check that you have at least .060" clearance between the bottom of the rocker's body and the spring retainer too. Some Rockers do not provide enough clearance. Remember, if you have guideplates you will need hardened pushrods, which are a good idea regardless.