Chevrolet 70 1969 Series, Shop Manual

Page: 357 / 913

ENGINE FUEL SYSTEM 6M -30
The governor is mounted between the engine
blower and the flywheel housing as illustrated in
figure 18. One end of the governor weight shaft is
splined to a drive plate attached to the driven blow­
er timing gear to provide a means of driving: the
governor. The other end of the shaft is supported
by a bearing in the blower drive support (fig. 17).
A cover and lever assembly, control housing,
spring housing, and governor weight and shaft as­
sembly are the basic parts of the governor.
O P E R A T IO N
The governor holds the injector racks in the
full fuel position for starting when the speed con­
trol lever is in the idle position. Immediately aiter
starting, the governor moves the injector racks
to the position required for idling.
The centrifugal force of the revolving governor
low and high speed weights is converted into linear
motion which is transmitted through the riser and
operating shaft to the operating shaft lever. One
end of this lever operates against the high and low
speed springs through the spring cap, while the
other end provides a moving fulcrum on which the
differential lever pivots.
When the centrifugal force of the revolving
governor weights equal the force exerted by the
high or low speed spring (depending on the speed
range), the governor stabilizes the engine speed
for a given setting of the governor speed control
lever.
In the low speed range, the centrifugal force
of the low and high speed weights operate together
against the low speed spring. As the engine speed
increases, the centrifugal force of the low and
high speed weights together compress the low speed
spring until the low speed weights are against their
stops, thus limiting their travel, at which time the
low speed spring is fully compressed and the low
speed spring cap is within .0015" of the high speed
plunger.
Throughout the intermediate speed range the
operator has complete control of the engine because
the low speed gap is closed and the low speed
weights are against their stops, and the high speed
weights are not exerting enough force to overcome
the high speed spring.
As the speed continues to increase, the cen­
trifugal force of the high speed weights increases
until this force can overcome the high speed spring
and the governor again takes control of the engine,
limiting the maximum engine speed.
Fuel rods are connected between the control
link operating lever and each injector control tube
lever. A vertical pin in the differential lever en­
gages the slot in the control link lever fork. This
arrangement provides a means for the governor to
change the fuel settings of the injector rack control
levers.
IDLE SPEED
AD JU STIN G SCR E W
G O V E R N O R
H O U S IN G '
SPRING
CAP
SHIMS
G A SKET v
IDLE SPEED
AD JU STIN G SCR E W
SPRING
CAP
Figure 1
9— Governor
Spring Assemblies
The engine idle speed is determined by the
force exerted by the governor low speed spring.
When the governor speed control lever is placed
in the idle position, the engine will operate at the
speed where the force exerted by the governor low
speed weights will equal the force exerted by the
governor low speed spring.
The engine idle speed is adjusted by changing
the force on the low speed spring. This is accom­
plished by turning the idle speed adjusting screw
as outlined in this section.
The engine maximum no-load speed is deter­
mined by the force exerted by the high speed spring.
When the governor speed control lever is placed
in the maximum speed position, the engine will
operate at a speed where the force exerted by the
governor high speed weights will equal the force
exerted by the governor high speed spring.
The maximum no-load speed is adjusted by in­
creasing or decreasing the tension on the high
speed spring. This is done by turning the high
speed spring retainer nut on governors with the
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK SH O P M A N U A L