PRW 33 PQ Series GM LS Series Shaft Mount Rocker - Manual (Page 2)

Page 2
Step 3: If installed, remove any rocker arm studs from the cylinder heads. Inspect all rocker stud bolt holes to
ensure that the threads have not been damaged during removal of the studs. Utilize a thread chaser to assure the
threads are clean and to mount the rocker stands securely to the cylinder head.
Step 4: Verify that all rocker stand bolts can be threaded to operational depths through the rocker shafts and
into the rocker arm stud holes, prior to applying torque to any of the rocker stand bolts. Confirm adequate depth
for rocker stand bolts with calipers or depth gauge. Check rocker arm shaft bolts to be certain that none extend
beyond the depth of the rocker arm stand when installed should be shortened using a bench grinder. Be sure to
clean up any modified threaded bolt ends with a thread chaser after grinding.
Step 5: If longer than stock valve stems are being utilized, rocker stand shims will be required. If required,
make certain to utilize equal thickness combinations of shims under each pair of rocker stud holes. Two (2)
thicknesses of rocker arm pedestal shims are included (.100”, and.050”) and eight (8) each are included with
each kit. Carefully inspect the rocker arm geometry to ensure that the roller tip is centered (or slightly over
center) and nearly parallel to the valve spring retainer. Shims should be added under the rocker stand to raise
the shaft proportionate to the added length of the valve stems. Shimming the heads will not be required if
cylinder heads are equipped with standard length intake and exhaust valves.
DETERMINE CORRECT STAND HEIGHT
Install the rocker stands on the cylinder head using the 8mm attaching bolts. The stands should be placed on the
head so that the stamped letters face the valve stem. Remove a rocker arm from one of the shafts and place that
shaft on a stand. Take the shaft height gage supplied with the kit and place it on the valve stem as shown in
Figure 1.
The gage should contact the top of the valve and the rocker shaft as shown in Figure 1.
If the gage contacts the shaft before touching the top of the valve stem, as shown in Figure 2, remove a
corresponding amount of material from the stud bosses on the cylinder head. This will lower the rocker stand on
the cylinder head.