The rocker arms open and close the valves through a very simple ball pivot type operation.
REMOVAL & INSTALLATION
See Figure 1
- Refer to the rocker arm (valve) cover, removal and installation procedures in this section and remove the valve cover.
- Using a socket wrench, remove the rocker arm bolts, the ball washer and the rocker arm.
If only the pushrod is to be removed, back off the rocker arm bolt, swing the rocker arm aside and remove the pushrod. When removing more than assembly, at the same time, be sure to keep them in order for reassembly purposes.
- Inspect the rocker arms and ball washers for scoring and/or other damage, replace them (if necessary).
If replacing worn components with new ones, be sure to coat the new parts with Molykote® or an equivalent engine assembly pre-lube, before installation.
- Install the pushrod and pushrod guide, if removed.
- Loosely install the ball washer, rocker arms and bolts.
Adjust the valves:
- Rotate the crankshaft until the mark on the damper pulley aligns with the 0 mark on the timing plate and the No. 1 cylinder is on the compression stroke.
To determine if the No. 1 cylinder is on the compression stroke, shake the rocker arms of the No. 1 cylinder, if they move the cylinder is on the compression stroke, if they don't move the cylinder is on the exhaust stroke. If the cylinder is on the exhaust stroke, it will be necessary to rotate the crankshaft one more full revolution to bring No. 1 back to top on compression.
- With the engine on the compression stroke, adjust the exhaust valves of cylinders No. 1 & 3 and the intake valves of cylinders No. 1 & 2.
To adjust the valves, tighten the rocker arm studs to the specified torque:
1985-86: 20 ft. lbs. (28 Nm).
- Rotate the crankshaft one complete revolution and align the mark on the damper pulley with the 0 mark on the timing plate.
- With the engine on the No. 4 compression stroke, tighten the retainers for the exhaust valves of cylinders No. 2 & 4 and the intake valves of cylinders No. 3 & 4.
- Install the rocker arm cover. For details, please refer to the procedure found earlier in this section.
See Figures 2, 3, 4, 5, 6 and 7
- Refer to the Valve Cover, Removal and Installation procedures in this section and remove the valve covers.
- Using a socket wrench remove the rocker arm-to-cylinder head nuts, the ball washers, the rocker arms and the pushrods (if necessary).
If you are removing more than one rocker arm, nut, washer and pushrod at a time, keep each assembly tagged, arranged and/or sorted to assure installation in their original locations.
- Inspect the parts for excessive wear and/or damage, then replace any parts (if necessary).
If replacing any parts with new ones, coat the new parts with Molykote® or an equivalent engine assembly pre-lube.
- If removed, install the pushrod.
- Loosely install the rocker arm, ball pivot and nut.
- For the 4.3L (VIN W) engine and any 1993-94 4.3L (VIN Z) engines which are equipped with screw-in type rocker arm studs with positive stop shoulders, Tighten the rocker arm adjusting nuts against the stop shoulders to 20 ft. lbs. (27 Nm). No further adjustment is necessary, or possible.
- For all 1985-92 and most later 4.3L (VIN B or Z) engines (which are not equipped with screw-in type rocker arm studs and positive stop shoulders), properly adjust the valve lash. For details on valve lash adjustment, please refer to General Information & Maintenance of this information.
- Install the rocker arm cover(s) to the cylinder head.