Chevrolet 70 1969 Series, Shop Manual

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G ASO LINE ENG INES 6 A -9
ROCKER A R M A N D SHAFT
ASSEMBLY REPLACEMENT
R E M O V A L
1. Remove rocker arm covers, referring to
instructions previously given.
2. Loosen rocker arm shaft bracket bolts
gradually until spring pressure is fully relieved
at rocker arms. Lift off the rocker arm shaft and
brackets, with attaching bolts, as an assembly.
3. Remove push rods and identify in some
manner so they can be returned to original posi­
tion at assembly.
N O T E : Valve lifters should be installed in
bores from which they were removed.
IN S T A L L A T IO N
1. Place push rods in original positions, then
place rocker arm shaft and bracket assembly (fig.
14) on cylinder head, being careful to engage rocker
arm screws with sockets in push rods. Tighten
bracket bolts to 20 to 25 foot-pounds torque.
2. Check clearance between rocker arm end
brackets and adjacent rocker arm. If a clearance
of approximately 0.030 inch does not exist, loosen
end bracket bolts and relocate brackets as allowed
by clearance in bracket hole, then tighten bolts to
specified torque.
3. Make initial adjustment to provide clear­
ance of 0.014 inch at intake valves, and 0.022 inch
at exhaust valves.
4. Lubricate rocker arms with engine oil.
5. Install rocker arm covers temporarily while
engine is run to warm up to operating temperature.
With engine idling and temperature at 160 degrees,
adjust intake valves to 0.012 inch and exhaust valves
to 0.018 inch. After valve clearance is made, in­
stall rocker arm cover using new gasket.
MANIFOLD REPLACEMENT
E X H A U S T M A N IF O L D S (A L L ENGINES)
1. Disconnect exhaust pipe from exhaust
manifold.
2. Bend locks away from manifold attaching
bolts, then remove bolts. Figure 12 shows exhaust
manifolds and attaching parts for V6 engines.
3. Remove manifolds and gaskets.
4. When installing exhaust manifolds, use new
gaskets and bolt locks, tighten manifold bolts to
20 foot-pounds, and secure bolts with lock tabs.
IN T A K E M A N I F O L D
1, Remove air cleaner or adapter and hoses
from carburetor.
2. Disconnect throttle and choke controls
from carburetor. Also disconnect vacuum line and
hydraulic governor line (when used).
3. Disconnect fuel line, then remove carbu­
retor from manifold.
4. Remove manifold bolts with attached spark
plug wire supports, and disconnect wires from
spark plugs.
5. Remove remaining bolts attaching intake
manifold to cylinder heads, then remove intake
manifold and gaskets.
6. When installing intake manifold use new
gaskets and reverse removal procedure described
above.
Correct intake manifold bolt torque is
given in “ Torque Wrench Specification".
N O T E : After engine has been started and
warmed up to normal operating temperature re­
check manifold bolt torque to assure sufficient
torque to prevent air leakage at manifold gaskets.
W A T E R M A N IF O L D
The outlet manifold assembly is installed be­
tween the cylinder heads at front of engine and
contains engine thermostats. Tapped holes are
provided for heater hose connections and temper­
ature gauge sending unit.
1. Drain cooling system to a point below cyl­
inder heads.
2. Disconnect radiator hose from water outlet
housing.
3. Remove manifold-to-cylinder head bolts,
then remove the water manifold and gaskets.
N O T E : Refer to E N G IN E C O O L IN G S Y S T E M
(SEC. 6K) in this manual for instructions for
inspecting and replacing thermostats.
4. When installing water outlet manifold use
new gaskets and tighten bolts to 20 to 25 foot­
pounds torque.
5. After radiator hose is connected, and
sending unit installed, fill cooling system and
inspect for leaks.
CYLINDER HEAD A N D GASKET
REPLACEMENT
Cylinder head can be replaced on most truck
models with gasoline engines by following the in­
structions outlined in following paragraphs. On
rear-engine school buses, engine should be remov­
ed from chassis to provide sufficient space to re­
move and install cylinder heads. It will facilitate
the procedure on Tilt-Cab Models if the engine
shield on cab rear support is removed.
C Y L IN D E R H E A D R E M O V A L
N O T E : When left-hand head is to be removed
from tilt cab model, the transmission control rods
must first be removed.
CHEVROLET SERIES 70-80 HEAVY DUTY TRUCK SHO P M ANUAL