Chevrolet 70 1969 Series, Shop Manual

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E N G IN E 6-32
6. Install spark plugs using new gaskets and tighten to
23 to 27 foot-pounds with torque wrench and special
spark plug wrench. Be sure plugs are properly
gapped.
7. Install rocker arm covers using new gaskets. Correct
torque for rocker arm cover bolts is 3 to 5 foot­
pounds.
8. Clean valve lifter and push rod cover gasket surfaces
preparatory to installing lifter covpr
NOTE: If new camshaft and valve lifters are in­
stalled in an old engine block, and whenever a
new replacement engine or partial engine is
used, a 1-pint can of "Break-in Compound for
New Engine Camshafts" should be poured over
camshaft lobes and allowed to run down into
trough below camshaft and oil pan. Before
starting engine, add engine oil to proper level.
Do not drain crankcase containing "break-in"
compound until vehicle has been run 500 miles.
9. Install lifter and push rod cover and gasket and tigh­
ten the cover screws evenly and firmly.
MANIFOLD INSTALLATION
1. Install exhaust manifolds using new locks on each
pair of bolts. Tighten exhaust manifold bolts to 15 to
20 foot-pounds and bend locks against bolt heads.
2. Install intake manifold using new gaskets tighten
bolts to 20 to 25 foot-pounds, using care to draw
manifold bolts down evenly.
3. Install water manifold and outlet housing at front of
engine and install cover plates and gaskets and at rear
of cylinder heads.
INSTALLING ACCESSORIES
Refer to respective manual sections for information on
installation of such accessories as fuel pump, air com pres­
sor, starter, generator, distributor and carburetor.
VA LVE T IM IN G C H E C K
Valves m ust open and close in correct relationship to
upper and lower dead-center of crankshaft as indicated in
valve timing diagrams (fig. 53). W hen a check of valve
timing is necessary, following procedure may be used re­
ferring to markings at crankshaft pulley hub or pulley for
determining upper deadcenter on No. 1 cylinder.
1. Remove left-hand rocker cover from cylinder head to
provide access to rocker arms at No. 1 cylinder.
2. Turn engine clockwise (viewed from front of engine)
to U D C No. 1 m a rk at crankshaft pulley on com pres­
sion stroke. Both the intake and the exhaust valve on
No. 1 cylinder will then be closed.
3. On 4 0 1M and 478M engines adjust valve lash on No.
1 exhaust valve (front valve) to exactly 0.054 inch.
4. Turn engine clockwise until No. 1 exhaust valve opens
and begins to close, then with fingers try turning push
rod of No. 1 exhaust valve as engine is cranked slow­
ly. When push rod rotates with finger pressure, the 5
degree (center) m ark on pulley should be at pointer.
This will be about 1 revolution from starting point. If
push rod starts to rotate at any point between 10 de­
gree m a rk and U D C No. 1 m ark, the valve timing is
correct. Be sure to adjust exhaust valve clearance to
0.018 inch after performing the foregoing check.
5. If when checking valve timing, the push rod starts to
rotate at a point either before the 10 degree m a rk or
after the U D C No. 1 m ark, the camshaft (valve tim ­
ing) can be considered “ out of time.”
T o correct the timing, remove the engine front cover as­
sembly, then align marks on sprockets or gears as illus­
trated in Figure 39.
NOTE: When checking timing marks, (fig. 39),
it may be necessary to turn crankshaft several
revolutions to bring marks into position where
they will be indexed.
ENGINE LUBRICATION SYSTEM
Engine oil pan sum p provides a reservoir for lubricating
oil. Engine oil pump, driven by shaft which couples the oil
pum p to ignition distributor, is located in oil pan and is
fitted with an inlet oil screen. Oil pum p is high capacity,
rotor type. Oil filter (when used) is bracket mounted on
left side at rear of crankcase. Filter element is throw­
away paper type. Oil from pum p is discharged through
filter and into oil galleries in cylinder block. Oil passages
carry oil under pressure to all crankshaft, cam shaft and
connecting rod bearings. Pressure lubrication is also pro­
vided for valve lifters and valve-operating mechanism at
cylinder heads.
Cylinder walls and piston pins are lubricated by oil
thrown from connecting rod journals. Refer to Figure 54
for schematic illustration of engine lubrication system on
engine with gear-driven camshaft.
ENGINE TEST AND RUN-IN
After engine has been rebuilt and all accessories in- stand. After the unit is installed in vehicle, the same pro­
stalled, the unit should be given a preliminary run-in on a cedures should be applied.
CHEVROLET SERIES 70-80 HEAVY DUTY TRUCK S H O P M A N U A L