T&D Machine Products Chrysler B-1 Rocker Arm Assembly with 5/8" diameter rocker shafts - Manual (Page 2)

If the gage contacts the top of the valve stem and does not touch the rocker shaft,
as shown in Figure 3, add a corresponding amount of shims between the stand
and the cylinder head. This will raise the rocker stand and shaft to the correct
height.
4. DETERMINE
CORRECT PUSHROD LENGTH
Place a pushrod length checker into the lifter and install the rocker arm assemblies.
Be sure the cam is rotated to the base circle. Seat the bottom of the adjuster screw
up against the recess in the rocker arm and turn the adjuster screw clockwise one
full turn down. This is the initial adjuster position. Adjust the pushrod length tool to
the proper length, remove from the engine, and measure its overall length.