2G Engine Governor; Control Valve - Chevrolet 10 1971 Series Chassis Service Manual

ENGINE FUEL 6M-14
General Description ................................................... ..........................
Major Service O pe ratio n s................................................ .....................
Control V a lv e ......................................................................................
The Model 2G Carburetor Governor (fig. 2G) provided
with 350 V-8 engines is a mechanically driven vacuum
actuated mechanism set to govern engine speed at 4000
rpm maximum under full load conditions. With this limit,
full advantage of engine horsepower is allowed without
danger of excessive wear due to overspeeding. This 4000
rpm limit establishes an excellent pattern for shift con­
trol for automatic type transmissions.
The governor is comprised of two basic units; the cen­
trifugal control valve housed in the distributor (See En­
gine Distributors in Section 6Y), and a carburetor
actuator which is mounted on the carburetor throttle body
(fig. 2G). These two components are inter-connected by
tubing.
An engine overspeed warning device is incorporated
into the governor as shown in Figure 2G. A description
of the overspeed warning system will be found in Sec­
tion 6Y.
Operation
The function of the 2G governor is to limit engine speed
and yet allow a wider throttle opening when power is re­
quired. The throttle lever is connected to the throttle
shaft in such a manner that turning the throttle lever does
not actually force the throttle valve open but rather al­
lows them to follow the throttle lever because of the
governor spring tension. Thus when the throttle lever is
moved to wide open position, the position of the throttle
valve will be determined by vacuum on the diaphragm and
the tension of the governor or spring acting on the gov­
ernor lever.
Vacuum is applied to the diaphragm through a system
of vacuum passages and restrictions in the throttle body
and governor housing.

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).
G O VERN O R HOUSING
Removal
1. Remove the four governor cover attaching screws
and then the governor cover and gasket if used (fig.
3G).
2. Detach and remove the governor spring.

2G ENGINE GOVERNOR

(VACUUM SPINNER TYPE)
6M-14
6M-14
6M-14
GENERAL DESCRIPTION
A speed sensitive centrifugal
M AJO R SERVICE OPERATIONS
INDEX
Page
Governor H o u s in g ................ .............................................................
T r o u b le s h o o tin g ...................................................................................
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.
Fig. 1G — Distributor and Governor Mounting
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.
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6M-14
6M-16
10-30 CHEVROLET TRUCK SERVICE MANUAL