So I picked up a set of heads and they have Isky ductile rockers on them. Question is when setting up for push rod length checking with a hydraulic cam . Should the lifter be preloaded and how much. I have an adj rod and dial indicator. Just keep the rocker adj screw threads ant a minimum ? Probably over kill for a hyd, but hey why not? Is there a thread on this?? Thanks..

That rocker should have a 3/8 x24 thread per inch adjuster in it If it does set the rocker up so you can get zero preload and then add from 1/3 turn(1/3 of .042 ) to 3/4 turn to get the preload length needed. I would shoot for between 1 to 3 full threads expose under the rocker arm with the preload set

thanks Cab.