Chevrolet 10 Series 1968, Service Manual

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ENGINE FUEL 6M-8
DISTRIBUTOR CARBURETOR
IGNITION
SWITCH
AMBER
LAMP
LAMP BURN-OUT CHECKING CIRCUIT
~ 2 T
OIL PRESSURE
SWITCH
BATTERY
SPINNER VALVE
CARBURETOR ACTUATOR
BUTTERFLY VALVE
AIR INLET
F ig . 4 G - G overnor and Overspeed Warning Light Cross-Section
MAJOR SERVICE OPERATIONS
CONTROL VALVE
Whenever the distributor is removed for overhaul, the
governor control valve mechanism should be disassem­
bled and cleaned (see Engine Distributors in Section 6Y).
GOVERNOR HOUSING
Rem oval
1. Remove the four governor cover attaching screws
and then the governor cover and gasket if used.
2. Detach and remove the governor spring.
3. Remove the eight diaphragm cover attaching screws
and then the diaphragm cover. Hold the throttle
lever to avoid damage to the throttle valves and
loosen the nut attaching the governor lever and pin
assembly to the throttle shaft. Remove the governor
lever from the throttle shaft, then detach it from the
diaphragm rod by rotating the lever until the tang on
the rod clears the slot in the lever.
4. Remove the diaphragm assembly from the housing
and inspect for cracks or holes. If the diaphragm is
damaged in any way, it must be replaced.
5. Remove the three governor attaching screws, then
remove the leather seal retainer and leather seal.
6. Detach the governor housing from the throttle body.
7. The throttle lever and bearing assembly can be re­
moved by detaching the fast idle cam and pump rod
and removing the four attaching screws. No attempt
should be made to service the throttle lever bearing.
If the action is sticky or binding to the point that the
throttle return spring cannot overcome the binding,
the throttle lever assembly should be replaced.
C A U TIO N : Since the idle ports in the throttle
body were drilled after the throttle body was
assembled, the throttle valves were nicked dur­
ing the drilling operation. No attempt should be
made to remove the throttle valve or to further
disassemble the throttle body, since any slight
change in positioning of the throttle valves with
relation to the idle ports would seriously disrupt
carburetor operation.
Cleaning and Inspection
The throttle lever and bearing assembly should not be
immersed in any carburetor cleaner, since it might cause
damage to the neophrene seal protecting the ball bear­
ings. If the throttle body itself is immersed in solvent,
great care must be taken that the throttle shaft bearings
are blown completely dry with compressed air. They may
then be lubricated with very light machine oil. Since the
calibration of vacuum versus spring tension is of extreme
importance in governor operation, it can readily be seen
that there should be no bind whatsoever in throttle shaft
rotation. If any binding is found, the throttle body as­
sembly must be replaced.
Installation
1. Position the gasket carefully on the throttle body and
assemble the throttle lever and bearing assembly to
CHEVROLET TRUCK SERVICE MANUAL