Chevrolet 70 1969 Series, Shop Manual

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G ASO LINE ENGINES 6A-7
ENGINE REPLACEMENT
(TILT CAB MODELS)
G E N E R A L
The steps required to replace an engine in
tilt-cab models with gasoline engine will vary with
the models and optional equipment involved. Pro­
cedure which follows will serve as a guide for use
when engine replacement is necessary. In most
instances the transmission and engine should be
removed as an assembly.
R E M O V A L
1. Drain radiator and disconnect battery.
2. Disconnect oil cooler lines (when used).
Cooler lines are attached to fittings at bottom tank
on radiator. Oil will drain from lines and cooler
when lines are disconnected.
3. Disconnect electrical wiring and cables at
starter; also, disconnect engine ground strap.
4. Disconnect throttle and choke controls.
5. Disconnect transmission control rods, de­
tach hoses from surge tank. Remove air cleaners
and inlet hoses as necessary to permit removal of
control island assembly.
6. Remove control island, and cab rear sup­
port.
7. Disconnect exhaust pipes from manifolds.
8. Disconnect clutch control cylinder from
release lever and flywheel housing. The fluid line
may remain attached to cylinder to prevent fluid
from draining from clutch control system while
engine is removed.
9. Disconnect parking brake control (except
when air-operated brake is used) and speedometer
drive at rear of transmission.
10. Disconnect cooling system and heater
hoses.
11. Disconnect propeller shaft from trans­
mission.
IN-VEHICLE SER
VALVE SPRING REPLACEMENT
(CYLINDER HEAD INSTALLED)
In most vehicles it is possible to replace a
broken valve spring without removing cylinder
head by following the procedure outlined below:
When it is necessary to replace a valve spring
and/or seals on valve stems, the special tools
shown in figure 8 may be used to facilitate the
operation without removing the cylinder head. Pro­
ceed in following manner to replace valve spring
and retaining parts.
1. Remove valve rocker arm cover.
2. Remove spark plug from cylinder on which
work is to be done. Use spark plug gasket and in­
stall adapter (J-21546) in spark plug hole.
12. If air compressor is used, disconnect air
lines from compressor. In some cases the air
compressor mounting bracket may be detached
from engine and compressor may remain with
chassis when engine is removed.
13. If power steering is used, the power steer­
ing pump may be detached from engine and lines
may remain connected to prevent fluid loss when
removing engine.
14. Attach overhead hoist securely to engine
sling, then raise power plant slightly to remove
weight from engine mountings. Remove mounting
bolts from front and rear mountings, then raise
power plant and remove from chassis.
15. Refer to applicable procedures in T R A N S ­
MISSIONS A N D C L U T C H E S (SEC. 7) for instruc­
tions, and remove transmission and clutch from
engine.
IN S T A L L A T IO N
Assemble clutch components and transmission
to engine, referring to applicable instructions in
TRANSM ISSIONS A N D C L U T C H E S (SEC. 7) in this
manual.
Install power plant by reversing order of
"Removal" procedure, taking necessary precau­
tions to maintain cleanliness and to avoid damage
to the engine components.
After engine is installed, check operation of
control linkage, fill cooling system and check for
leaks.
Fill crankcase with engine oil of recommended
grade and viscosity.
Start engine, make adjustments at carburetor,
set ignition timing and adjust valve lash. N O T E : If
engine has been run in on test stand, the foregoing
adjustments will have been made previously and
need not be repeated.
:E OPERATIONS
3. Remove rocker arm shaft and bracket as­
sembly from cylinder head. Install a 3/ 8-16 stud
in bracket bolt hole adjacent to the valve spring to
be removed. Stud must have sufficient threads to
permit screwing stud nut down one-half inch after
compressor contacts valve spring cap.
4. Turn engine crankshaft to place piston at
B O T T O M of stroke. Attach compressed air supply
line to adapter and turn on air supply. Air pres­
sure in cylinder will hold valves against seats
while spring and retaining parts are removed.
5. Assemble valve spring compressor (J-
21544) and nut on stud as shown in figure 8, then
with wrench, turn nut to force compressor down
against valve spring cap meanwhile striking spring
cap lightly with hammer to unseat the valve locking
keys. Continue to turn the stud nut until spring is
compressed sufficiently to permit removal of the
CHEVROLET SERIES 70-80 HEAVY DUTY TRUCK SHOP MANUAL