I am trying to find out what pushrod length I need. I have a 350 roller cam and stock roller lifters, comp adjustable pushrod, checking springs, and 1.6 roller rockers. My question is once you have your wear pattern on the valve correct do you tighten the poly lock till you get zero lash then remove the pushrod and measure it, then add say .050 for lifter preload?

 

Not exactly...

You tighten the Polylock to get zero lash; then you spin the motor and observe the pattern; then you loosen the Polylock, adjust the push rod, tighten the Polylock, spin the motor, and observe the pattern; then you repeat until the narrowest pattern is found, WITHOUT ANY CONCERN WHATSOEVER FOR WHERE ON THE VALVE STEM THE PATTERN HAPPENS TO LAND.

At that point you will have determined a push rod length that is the correct for a bottomed-out (shortest possible) lifter. Subtract about .100" to get the proper length for a mostly extended (considerably taller) lifter.