Chevrolet 10 Series 1967, Service Manual

Page: 330 / 605

ENGINE FUEL 6M-6
of vacuum passages and restrictions in the throttle body
and governor housing. A speed sensitive centrifugal
valve in the distributor acts as a vacuum break so that
there is no vacuum applied to the diaphragm until the
desired governed speed is reached. When the governed
speed is reached the valve is closed and vacuum is ap­
plied to the diaphragm which acts to close the throttle
valves in opposition to the governor spring tension.
When power is required as load is increased, engine rpm
will drop causing distributor valve to open and allow the
governor spring to open the throttle valves further.
I I I I I Is
BATTERY
SPIN N ER VALVE
AMBER
LAMP
LAMP BURN-OUT CHECKIN G CIRCUIT
IGN ITIO N
SWITCH
- ~ £ -
OIL PRESSURE
SWITCH
DISTRIBUTOR CARBURETOR
BUTTERFLY VALVE
ACTUATOR
AIR INLET
Fig. 4 G - G overnor and Overspeed W arning 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
6
Y).
GOVERNOR HOUSING
Removal
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 th# 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.
CAUTION: 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.
CHEVROLET TRUCK SERVICE MANUAL