Oil Pan Installation; Cylinder Head Installation; Valve Train Component Installation; Valve Adjustment - Chevrolet 1991 Light Duty Truck Repair Manual

6A3-22 4.3L V6 ENGINE
Figure 38—Measuring Connecting Rod Side
Clearance

OIL PAN INSTALLATION

Install or Connect (Figure 39)
• Apply PST sealant (GM part number 1052080 or
equivalent) to the front cover to block joint and to
the rear crankshaft retainer seal to block joint.
Apply the sealant about 25 mm (1-inch) in both
directions from each of the four corners (figure 39).
1. Oil pan gasket to the oil pan.
2. Oil pan to the engine.
3. Oil pan bolts and nuts.
| ^ | Tighten
• Bolts to 11 N-m (100 in. lbs.).
• Nuts to 23 N-m (17 ft. lbs.).

CYLINDER HEAD INSTALLATION

2 ! ciean
• Gasket surfaces on the block and cylinder head.
Install or Connect (Figure 40)
1. Head gasket.
• Do not use sealer on composition gaskets.
• Place the gasket over the block dowel pins.
2. Cylinder head. Carefully guide the cylinder head
into place over the dowel pins and gasket.
3. Cylinder head bolts. Coat threads of the cylinder
head bolts with sealing compound (GM part num­
ber 1052080 or equivalent) and install finger-tight.
• Cylinder head bolts in three steps, using the
sequence shown in figure 40.
— The first sequence should go to 34 N-m (25
ft.lbs).
— The second sequence should go to 61 N-m
(45 ft.lbs).
— Final torque sequence should be 90 N m
(65 ft. lbs.).
VALVE TRAIN COMPONENT
INSTALLATION
Important
Replace all hydraulic lifters, change the engine oil
and filter and add GM Engine Oil Supplement (GM
part number 1052367 or equivalent) to the engine
oil whenever a new camshaft is installed.
Install or Connect (Figure 41)
1. Hydraulic lifters to the block. Lubricate the lifter
roller and body with high viscosity oil with zinc
(GM part number 12345501 or equivalent).
2. Restrictors (46) and retainer (41) with bolts (40).
Tighten
• Bolts (40) to 16 N-m (145 in. lbs.).
3. Pushrods.
• Seat the pushrods into the socket of the
hydraulic lifters.
Important
• When new rocker arms and/or balls are
installed, coat their bearing surfaces with high
viscosity oil with zinc (GM part number
12345501 or equivalent).
4. Rocker arms (44) with balls (43) on to the proper
stud.
5. Rocker arm nuts (42) on to the studs.
• Align the push rod into the rocker arm while
tightening rocker arm nut (42).
Adjust
• Valves. Refer to "Valve Adjustment."

VALVE ADJUSTMENT

1. Crank the engine until the mark on the torsional
damper lines up with the "0" mark on the timing
tab and the engine in the number one firing posi­
tion. This may be determined by placing fingers on
the number one valve as the mark on the damper
comes near the "0" mark on the timing tab. If the
rocker arms are not moving, the engine is in the
number one firing position. If the rocker arms
move as the mark comes up to the timing tab, the
engine is in the number four firing position and
should be turned over one more time to reach the
number one position.
2. With the engine in the number one firing position
as determined above, the following valves may be
adjusted:
Exhaust valves 1, 5, 6.
Intake valves 1, 2, 3.
(Even numbered cylinders are in the right bank;
odd numbered cylinders are in the left bank, when
viewed from the rear of the engine).