How to adjust hydraulic lifters?
To adjust hydraulic lifters with the engine running, install a special oil shroud or some other device for catching oil spray off the rocker. Start and run the engine until it reaches operating temperature. Tighten all rockers until they are quiet. One at a time, loosen a rocker until it clatters. Then tighten the rocker slowly until it quiets down. This is zero valve lash.