just watch the valves as you turn the crank, when the two rockers are bottomed you can do the valves for the cyl. but you have to watch because some cars have cams that over lap so one valve will start opening when the other is closing. you want to do it when neither is going on. procedure from gm service manual;
Install the pedestal and rocker arm assembly.
Notice: This bolt is designed to permanently stretch when tightened, and therefore MUST be replaced anytime it is removed. The correct part number fastener must be used to replace this type of fastener. Do not use a bolt that is stronger in this application. If the correct bolt is not used, the parts will not be tightened correctly. The system or the components may be damaged.
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Install the rocker arm pedestal retaining bolts.
Tighten the bolts to 15 N·m (11 lb ft). Use the J 36660-A in order to rotate the bolts an additional 90 degrees.
Install the right side rocker arm cover. Refer to Valve Rocker Arm Cover Replacement .
Install the left side rocker arm cover. Refer to Valve Rocker Arm Cover Replacement .
Tighten the bolts to 10 N·m (89 lb in).
Inspect for proper completion of the repairs.
Listen for valve train noise.
1998 Bonneville SSE
2007 Monte Carlo LT-KYB, Clarion, Polk audio, Kicker
1999 Yukon SLE-KYB, Air lift, Reese dual-cam, Tekonsha
1987 Firebird-355/th400-nothing stock