Chevrolet 10 Series 1970 Service Manual page 371

DISTRIBUTOR
SPINNER VALVE
AMBER
LAMP
not actually fo rc e the throttle valve open but rather a l­
low s them to fo llo w the throttle le v e r because of the
go v ern o r spring tension.
m oved to wide open position, the position o f the throttle
va lve w ill be determ ined by vacuum on the diaphragm and
the tension of the govern or o r spring acting on the g o v­
ern o r le v e r.
Vacuum is applied to the diaphragm through a system
o f vacuum passages and res trictio n s in the throttle body
and go vern or housing. A
CONTROL VALVE
W henever the d istribu tor is rem oved fo r overhaul, the
g o ve rn o r control va lve m echanism should be d isa ssem ­
bled and cleaned (See Engine D istrib u tors in Section 6Y).
GO VER N O R H O U SIN G
Removal
1. R em ove the four g o vern or c o v e r attaching screw s
and then the govern or c o v e r and gasket if used (fig .
3G).
2. Detach and rem ove the g o vern or spring.
3. Rem ove the eight diaphragm co v er attaching screw s
and then the diaphragm co v e r.
le v e r to avoid damage to the throttle v a lves
loosen the nut attaching the govern o r le v e r and pin
assem bly to the throttle shaft. R em ove the govern or
le v e r fro m the throttle shaft, then detach it fro m the
LAMP BURN-OUT CHEC KING CIRCUIT
IG N IT IO N
SW ITCH
ENGINE OVER-SPEED WARNING SYSTEM
F ig . 2 g —G o v e rn o r and O verspeed W a rn in g L ig h t S chem atic
Thus when the throttle le v e r is
speed sen sitive centrifugal
MAJOR SERVICE OPERATIONS
Hold the throttle
OIL PRESSURE
SW ITCH
va lve in the distribu tor acts as a vacuum break so that
there is no vacuum applied to the diaphragm until the
d es ire d governed speed is reached. When the governed
speed is reached the va lve is closed and vacuum is ap­
plied to the diaphragm which acts to c lose the throttle
va lv e s in opposition to t h e
When pow er is requ ired as load is increased, engine rpm
w ill drop causing d istribu tor valve to open and allow the
govern or spring to open the throttle va lves further.
diaphragm rod by rotating the le v e r until the tang on
the rod cle a rs the slot in the le v e r.
4. R em ove the diaphragm assem bly fro m the housing
and inspect fo r cracks o r holes. If the diaphragm is
damaged in any way, it must be replaced.
5. R em ove the three govern or attaching screw s, then
rem ove the leath er seal reta in er and leath er seal.
6. Detach the govern or housing fro m the throttle body.
7. The throttle le v e r and bearing assem bly can be r e ­
moved by detaching the fast idle cam and pump rod
and rem oving the four attaching screw s. No attempt
should be made to s e rv ic e the throttle le v e r bearing.
If the action indicates excessive frictio n to the point
that the throttle
and
the binding, the throttle le v e r assem bly should be
replaced.
CAUTION: Since the idle ports in the throttle
ENGINE FUEL 6M -7
CARBURETOR
BUTTFRFLY VALVE
CARBURETOR ACTUATOR
1111111
*■ =
BATTERY
govern or sprin g tension.
return spring cannot overco m e
CHEVROLET TRUCK SERVICE MANUAL