Rocker arms and pushrods – removal, inspection, installation and adjustment
1. Disconnect the cables from the negative terminals of the batteries (see Engine electrical systems).
2. Remove the valve cover (Valve cover – removal and installation).
Removal
3. Mark the rocker arm/pedestal assemblies to ensure that they will be reinstalled in their original locations. Remove the rocker arm/pedestal bolts and remove the rocker arm/pedestal assemblies.
4. Mark the crossheads (the pieces that bridge each pair of intake and exhaust valves) to ensure that they will be reinstalled in their original locations. Remove the crossheads.
Caution: The sockets may drop from the rocker arms when lifting them from the cylinder head. Secure the rocker arm sockets before lifting them from the cylinder head.
5. Mark the pushrods to ensure that they will be reinstalled in their original locations. Remove the pushrods. Note: Lift out the intake and exhaust pushrods for the No. 5 and No. 6 cylinders through access holes in the cowl.
Inspection
6. Disassemble the rocker arms, pedestals and shafts and wash them, along with the crossheads, in clean solvent. Keep each rocker arm pair, the rocker shafts, the pedestal and related parts together. If necessary, use a wire brush to remove deposits. Rinse the parts in hot water and blow them dry with compressed air.
7. Inspect the oil passages in the rocker arms, rocker shafts and pedestals. Blow out all lubrication passages with compressed air to remove any debris.
8. Inspect the bearing surface of each rocker shaft for scoring, cracks and galling, and for any other excessive wear. Inspect the socket and the ball insert for excessive wear. If the retainer is weak, replace it.
9. Measure the inside diameter of each rocker arm bore and the outside diameter of each rocker shaft. Compare your measurements to the maximum allowable diameter for rocker arm bores and to the minimum allowable diameter for rocker shafts. If a rocker arm or rocker shaft is worn excessively, replace it.
10. Inspect each pushrod ball and socket for cracks and any signs of scoring. Roll each pushrod on a clean flat surface with the socket end hanging off the end of the bench. If a push-rod is bent, or excessively worn, replace it.
11. Inspect each crosshead for cracks and excessive wear, especially around the rim of the crosshead/valve tip contact area. If a crosshead is damaged or excessively worn, replace it.
Installation
12. Install the pushrods, with the ball ends facing down, in their original locations. Make sure that the pushrods are fully seated in the tappets.
13. Lubricate the valve tips with clean engine oil and install the crossheads in their original locations.
14. Lubricate the rocker shafts and the rocker shaft bores in the rocker arms with clean engine oil. Reassemble the rocker arm/ rocker shaft/pedestal assemblies.
15. Lubricate the crossheads and the push-rod sockets with clean engine oil and install the rocker arm/pedestal assemblies in their original locations. Install the rocker arm/pedestal bolts and tighten them to the torque listed in this Chapter’s Specifications.
16. Before installing the valve cover, check and, if necessary, adjust the valve clearance (see below).
17. After the valve clearance has been checked and, if necessary, adjusted, install the valve cover (Valve cover – removal and installation).
Valve clearance check and adjustment
Note: Valve clearance checking is only necessary after servicing valvetrain components.
18. Position the engine at Top Dead Center (TDC) for cylinder number 1 (Top Dead Center (TDC) for number one piston – locating).
19. With the engine in this position, measure the valve clearance at the following rocker arms:
INTAKE – I, 2 and 4
EXHAUST – 9, 3 and 5
20. Measure the valve clearance by inserting a feeler gauge between the rocker arm socket and the crosshead. Compare your measurements to the valve clearance ranges listed in this Chapter’s Specifications.
21. If the valve clearance is incorrect for any of the above intake or exhaust valves, loosen the locknut and then turn the adjusting screw until the clearance is correct. Set the valve clearances to the dimension listed in this Chapter’s Specifications. When the clearance is correct, tighten the locknut securely (see this Chapter’s Specifications for the proper torque reading) and then re-check the clearance to make sure that it didn’t change as a result of tightening the nut.
22. Using the barring tool, rotate the engine one complete revolution (360-degrees). With the engine in this position, measure the valve clearance at the following rocker arms:
INTAKE – 3, 5 and 6
EXHAUST – 2, 4 and 6
23. Following Steps 20 through 22, measure and adjust the valve clearances for the remaining valves.
24. Install the valve cover (Valve cover – removal and installation).