PRW 33 PQ Series GM LS Series Shaft Mount Rocker - Manual (Page 3)

Page 3
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.
NOTE: The shaft height gage supplied with this assembly is manufactured for 0.550" of valve lift. For lifts less
than 0.550", the shaft height should be raised by half the difference, and for lifts greater than 0.550", the shaft
height should be lowered by half the difference. (i.e.: For 0.650" lift, the shaft should be 0.050" lower than the
gage, and for 0.500" lift, the shaft should be 0.025" higher than the gage).
Step 6: Torque the 8mm pedestal mounting hex socket cap screws to OEM or cylinder head manufacturer’s
specifications. Do not exceed the specifications provided on Page 4. Any bolts that thread into an intake runner
should be coated with a thread sealant such as Loctite®.
Step 7: Install the rocker arms onto the rocker arm pedestal one pair at a time. If pushrod length has already
been determined and pushrods installed, back the adjusters out until the base of the adjuster seats against the
rocker body. If pushrod length has not been verified, please refer to the Section: Pushrod Length; Checking
to Determine Proper Length to ascertain the appropriate pushrod lengths. Once completed, install the
pushrods, and continue Step 7 as detailed below.
Make certain that the number 1 cylinder is at TDC and the pushrods are properly seated in the valve lifter at one
end and the valve lash adjuster at the other. The rocker arms should rest in the pedestal/stand without any
pressure between the valve lash adjuster and pushrod. Install the 5/16” socket head machine screws through the
rocker shafts into the rocker stands; hand-tighten until snug and then torque to specifications detailed below.
Upon installing the first pair of rocker arms, rotate the crankshaft 90 degrees and install the next pair of rockers.
Follow the engine firing order until all rocker arms have been installed.
NOTE: Never attempt to install or remove rocker arm shaft machine screws while valve spring pressure exerts
a load. Attempting to do so may seriously damage the shaft or other component parts.
Step 8: Place a few drops of oil on the valve lash adjuster threads prior to installation in each rocker arm.
Tighten the adjuster against the pushrod by hand until bottomed out. Back the adjuster out 1 turn. Thread the
adjuster nut onto the valve lash adjuster and tighten to 25 lbs/ft to seat the adjuster.
NOTE: It is critical that the adjuster is backed out one full turn before applying torque to the adjuster lock nut.
Failure to do so may result in damage to the adjuster and rocker arm.
Step 9: Once the valve lash adjuster has been seated, loosen the adjuster nut and set the adjuster for valve lash.
Retighten the adjuster nut to 25 lbs/ft.
NOTE: Do not run the rocker arm with the adjuster bottomed-out. Doing so will result in damage to the
rocker arm and other engine components. The rocker arm should not be operated with the adjuster screw
more than one turn up or down, from the initial adjuster position. Doing so can cut off the flow of oil to the
rocker arm.