ROCKER ARM SIDEPLAY ADJUSTMENT
The rocker arms, which are the vertical metal pieces that contain the valve adjustment nuts, will move up or down when pushed by hand. Measure the two gaps where the rocker arms contact the horizontal piece at the bottom. This horizontal piece has several names, including lower rocker arm bearing carrier (LRABC) and rocker arm end plate. This lower rocker arm bearing carrier (LRABC) is held in place by three T45 torx screws in a triangle pattern (on its side) and one large head bolt. The gaps should be between .05mm and .30mm. The smaller the gap the quieter the engine. The procedure is to loosen the 3 Torx screws and, after marking the lower head bolt, loosen it also. Snug them back up just enough to hold an adjustment and then tap the LRABC until you have about .05mm end play (gap). Check the gap after tightening because it may tighten up slightly as you torque the screws and bolts back to spec.
Retorque the T45 torx screws to 15 ft.lb. Retorque the head bolt to 17 ft.lbs. and then turn the bolt an additional 180-degrees (torque it and then move the wrench through another half circle).
http://www.ibmwr.org/r-tech/oilheads...ce_2-25-02.pdf