Chevrolet 1977 light duty truck, Руководство по обслуживанию

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NOISY VALVE LIFTERS
a. Check for broken valve springs and replace as
necessary.
b. Check for worn or sticking rocker arm s and
re p a ir or replace as necessary.
c. Check for worn or bent push rods and replace as
necessary.
d. Check for valve lifters incorrectly fitted to bore
size and correct as necessary.
e. Check faulty valve lifter plunger or push rod
seat an d replace lifters as necessary.
f. Check for plungers excessively w orn causing fast
leakdown und er pressure and replace as necessary.
g. Check for excessively w orn cam sh aft lobes and
replace if necessary.
h. Check valve lifter oil feed holes plugged causing
internal breakdow n and correct as necessary.
i. Check faulty valve lifter check ball, (nicked, flat
spot, or out o f round) and replace as necessary.
j. Check rocker arm retaining nut to be installed
upside dow'n and correct as necessary.
k. Check for end o f push rod excessively worn or
flaked and replace as necessary.
6 C y lin d er Engine
Contents
G e n e ra l D e s c r ip tio n ....................................................... 6A-7
Engine L u b r ic a tio n ......................................................... 6A-8
O n Vehicle S e rv ic e ......................................................... 6A-15
E ngine M o u n t s .............................................................. 6A-15
M a n ifo ld A ssem bly-N on-Integrated H e a d ........... 6A-16
Exhaust M anifold-Integrated H e a d ........................ 6A-16
Rocker A rm C o v e r ....................................................... 6A-17
Valve M e c h a n is m .......................................................... 6A-17
Valve Stem Oil Seal a n d / o r Valve S p r in g ........ 6A-17
Valve L i f t e r s ................................................................... 6A-18
C ylinder H e a d ............................................................... 6A-20
Rocker Arm S t u d s ........................................................ 6A-22
Valve G u i d e s ................................................................... 6A-23
Valve S e a t s ...................................................................... 6A-23
Valves................................................................................ .6A-24
Torsional D a m p e r ......................................................... .6A-24
Crankcase F ro n t C o v e r .............................................. .6A-25
Oil Seal (F ront C o v e r)............................................... .6A-26
C a m s h a f t .......................................................................... .6A-27
C a m sh a ft Bearings.........................................................6A-29
Oil P a n ............................................................................. .6A-30
Oil P u m p ........................................................................... 6A-30
Connecting Rod B e a rin g s.......................................... .6A-31
C ran k sh aft M ain B e a rin g s .........................................6A-32
Oil Seal (R ear M a i n ) ................................................. .6A-35
Piston and C onnecting Rod A ssem blies.............. .6A-36
Engine A ssem bly........................................................... .6A-40
C r a n k s h a f t .........................................................................6A-41
GENERAL DESCRIPTION
CYLINDER BLOCK
The cylinder block is m ade o f cast iron and has 6
cylinders a rra nge d "In -L in e " . Seven main bearings
support the cra n k sh a ft which is retained by recessed
b earing caps that are m achined with the block for
p ro p e r alignm ent and clearances. Cylinders are com ­
pletely encircled by coolant jackets.
CYLINDER HEAD
T he cast iron cylinder head provides a compression
ratio o f 8.3:1. It is cast with individual intake and
exhaust ports for each cylinder. Valve guides are integral
an d rocker a rm s are retained on individual threaded
studs pressed into head. Most 250 heads have integrated
inlet m anifold while the 292 uses separate inlet
manifolds.
CRANKSHAFT AND BEARINGS
The crankshaft is cast nodular iron and is supported
by seven m ain bearings. N u m b e r seven bearing is the
end thrust bearing. M ain bearings are lubricated from
oil holes which intersect the main oil gallery located on
the right side o f the block. The cam bearings are also fed
oil by intersecting holes with m ain oil gallery. The lifters
are located in the m ain oil gallery.
A d a m p e r assembly, on the forward end o f the
crakshaft, dam pens any engine torsional vibrations. The