Remove the valve covers. Loosen the rocker arm shaft retaining bolts a little at a time to avoid distorting the shaft, working from the ends toward the middle of the shafts. Some of the valves will be open when you loosen the rocker arm shaft bolts and the rocker arm shafts will be under a certain amount of valve spring pressure. Therefore, the bolts must be loosened gradually. Loosening a bolt all at once near a rocker arm under spring pressure could distort the rocker arm shaft. Prior to removal, scribe or paint identifying marks on the rockers to ensure they will be installed in their original locations. Remove the bolts and lift off the rocker arm shaft assemblies one at a time. Lay them down on a nearby workbench in the same relationship to each other that they're in when installed. They must be reinstalled on the same cylinder head. Note that the shafts with the larger notches go on the intake manifold side. Check the rocker arms and shafts for abnormal wear, pits, galling, score marks and rough spots. Don't attempt to restore rocker arms by grinding the pad surfaces. Measure the outside diameter of the rocker arm shaft at each rocker arm journal. Compare the measurements to the specific rocker arm shaft outside diameter. Measure the inside diameter of each rocker arm with either an inside micrometer or a dial caliper. Compare the measurements to the specific rocker arm bore diameter. Subtract the outside diameter of each rocker arm shaft journal from the corresponding rocker arm bore diameter to compute the clearance between the rocker arm shaft and the rocker arm. Compare the measurements to the specific clearance. If any of them fall outside the specified limits, replace either the rocker arms or the shaft, or both. Installation is the reverse of the removal procedure. Tighten the rocker arm shaft retaining bolts, in several steps, to the specific torque. Work from the ends of the shafts toward the middle.
