- Remove rocker arm covers.
- Crank engine until mark on torsional damper is aligned with ``0'' mark on timing tab and engine is in No. one cylinder firing position. Ensure engine is in No. 1 firing position by placing fingers on rocker arms of No. 1 cylinder as timing mark approaches ``0'' mark. If rocker arms are not moving engine is at the No. 1 firing position. If rocker arms are moving, engine is in the No. 4 firing position and should be rotated one revolution to the No. 1 position.
- Adjust the following valves with the engine in the No. 1 firing position: exhaust 1, 5 and 6; intake 1, 2 and 3. Adjust valves by backing off nut until lash is felt at the pushrod, then tightening nut until all lash is removed. This can be determined by rotating pushrod while tightening nut. When all lash is removed, tighten nut one full turn to center pushrod in lifter plunger.
- Crank engine one full revolution until mark on torsional damper and ``0'' mark on timing tab are aligned. This is the No. 4 cylinder firing position. Adjust the following valves: exhaust 2, 3 and 4; intake 4, 5 and 6.
Now, this says tighten 1 full turn. As do all old style V-6 and V-8 Chevys.
I tighten 1/2 to 3/4 turns. Loose is ALWAYS better than tight when it comes to valve lash or pre-load.