new roller rockers
The best way to do it is with a dial indicator on the pushrod end of the rocker. Make sure the lifter is on the cam base circle and then setup the dial indicator. Tighten to the correct preload and lock in place.
The other way is through turns on the adjusting nut, but you must account for the closed valve rocker ratio. For example, on my Cranes, the thread on the adjusting nut is 3/8-24 so each turn of the nut is 1/24 inches. The closed rocker ratio is 1.79 so my pushrod movement is:
# turns/24 X 2.79/1.79 or for 1/2 turn 0.5/24 X 2.79/1.79 = 0.032" preload
The other way is through turns on the adjusting nut, but you must account for the closed valve rocker ratio. For example, on my Cranes, the thread on the adjusting nut is 3/8-24 so each turn of the nut is 1/24 inches. The closed rocker ratio is 1.79 so my pushrod movement is:
# turns/24 X 2.79/1.79 or for 1/2 turn 0.5/24 X 2.79/1.79 = 0.032" preload
