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This is for the iron head pushrod motors and aluminum heads with non stock rockers installed
With number one piston on the firing position at TDC install the rockers on the studs, the valves that can be adjusted are:
EXHAUST: 1, 2, 3
INTAKE: 1, 5, 6
Tighten in the adjusting nuts until all lash is removed. This can be determined by rotating the pushrod while turning in the adjusting nut. Or by moving the pushrod up and down in the seat of the lifter/rocker arm and feeling the pushrod to rocker/lifter clearance. You want to remove all slack and clearance between these three pieces. Once the play (zero lash ) has been removed, Turn in the adjusting nut 1 and One-half turn (this is stock GM spec, I usually do 1/2 turn of preload) to center the lifter plunger. Now crank the engine over one complete revolution to number four firing position. These valves can now be adjusted:
EXHAUST: 4, 5, 6
INTAKE: 2, 3, 4
With number one piston on the firing position at TDC install the rockers on the studs, the valves that can be adjusted are:
EXHAUST: 1, 2, 3
INTAKE: 1, 5, 6
Tighten in the adjusting nuts until all lash is removed. This can be determined by rotating the pushrod while turning in the adjusting nut. Or by moving the pushrod up and down in the seat of the lifter/rocker arm and feeling the pushrod to rocker/lifter clearance. You want to remove all slack and clearance between these three pieces. Once the play (zero lash ) has been removed, Turn in the adjusting nut 1 and One-half turn (this is stock GM spec, I usually do 1/2 turn of preload) to center the lifter plunger. Now crank the engine over one complete revolution to number four firing position. These valves can now be adjusted:
EXHAUST: 4, 5, 6
INTAKE: 2, 3, 4