Chevrolet 70 1969 Series, Shop Manual

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E N G IN E 6-4
Sodium-cooled type exhaust valves are used on both V6
engines. These valves are faced with special hard alloy at
area which contacts valve seat in cylinder head.
Intake valves are of special material which is heat and
wear resistant. An oil seal ring is used to seal space be­
tween valve spring cap and intake valve stem.
Valve rocker arms at each cylinder head are installed
on a hollow rocker arm shaft which is supported by five
die-cast aluminum brackets. Push rods transmit motion of
mechanical valve lifters to rocker arms which have self­
locking adjusting screws for setting valve lash. Oil to lu­
bricate valves and operating mechanism is supplied
through passage in cylinder head which terminates at oil
hole at base of one of the rocker arm shaft brackets.
Each cylinder head has a pressed steel cover.
ENGINE OVERHAUL
For best accessibility and to facilitate overhaul proce­
dures the engine should be removed from chassis; howev­
er, most operations requiring only partial disassembly of
engine may be performed with engine cylinder block re­
maining in vehicle.
It is important to keep tools and surroundings clean
when working on engine. Use tools designed for special
purposes as listed in S P E C I A L T O O L S section. In most
cases special tools are illustrated. With engine removed
from vehicle a special repair stand should be used to sup­
port engine when making repairs.
Engine accessories such as generator, carburetor, fuel
pump, oil filter, fan, and other items mounted on engine
should be removed before starting to disassemble the
basic engine. Refer to various Maintenance Manual sec­
tions for instructions covering repair of various accessory
units. Alphabetical index at back of manual will aid in lo­
cating pages on which the accessory items may be located.
E N G IN E D ISA SSEM BLY
The procedures in following paragraphs are treated as
though engine were removed from vehicle; however, the
instructions are generally applicable when cylinder block
remains in vehicle.
*
MANIFOLD REMOVAL
1. Bend locks away from exhaust manifold bolt heads,
then remove bolts.
2. Remove exhaust manifolds and gaskets from cylinder
heads.
3. Remove bolts (and spark plug wire support brackets)
which attach intake manifolds to cylinder heads, then
remove intake manifold and gaskets.
4. Loosen hose clamps on hose between water manifold
and engine front cover, remove water manifold-
to-cylinder head bolts, then remove w'ater manifold
and thermostat housing as an assembly.
Figure 4 — Sp e c ial Tool for R e m o v in g a n d In sta llin g V a lv e Lifters w ith
C y lin d e r H e a d Installed Figure 5 — R e m o v in g Piston a n d C o n n e c tin g Rod w ith G u id e Set
CHEVROLET SERIES 70-80 HEAVY DUTY TRUCK SH O P M A N U A L