Chevrolet 10 Series 1968, Service Manual

Page: 399 / 713

ENGINE FUEL 6M-6
position and adjust swivel (D) on rod (E) so that it
enters freely into hole in lever (A).
3. Depress accelerator pedal to 1/4 inch from floor.
4. Install rod (H) and adjust swivel (J) so that it enters
freely into hole in lever (A).
5. Install clips on swivels.
6. Remove gauge pin from lever (A).
GOVERNORS
INDEX
Page
V elocity T y p e ....................................................................... 6M-6
General D e s c r ip t io n ....................................................... 6M-6
Maintenance and A d ju s tm e n ts ....................................... 6M-6
Adjustments ............................................................. 6M-6
Vacuum Spinner Type - 2G C a r b u r e t o r s .......................... 6M-7
Page
General D e s c r ip t io n ...................................................... 6M-7
M ajor Service O p e r a t io n s ............................................. 6M-8
Control V a l v e ............................................................. 6M-8
Governor H o u sin g ....................................................... 6M-8
T r o u b le s h o o t in g ............................................................. 6M-9
ENGINE GOVERNOR (VELOCITY TYPE)
GENERAL DESCRIPTION
A velocity type governor is used as optional equipment
on 230, 250, 292 and 307 truck engines.
The governor is mounted between the carburetor and
the intake manifold and automatically governs the maxi­
mum speed at which the truck engine may be operated,
which in turn limits the maximum speed at which the
vehicle may be operated.
The governor (fig. 1G) is operated by the vacuum exist­
ing in the intake manifold under varying conditions of
engine operation and the flow of air past the governor
valve. A shaft carried on a needle type roller bearing
extends through the body of the governor and this shaft is
offset from the center line of the throat. On the shaft is
mounted a throttle plate or throttle valve. The valve is
slightly offset on the shaft and in its wide open position is
about 10 degrees from the vertical (fig. 1G).
The gas mixture rushing from the carburetor through
the governor throat strikes the offset throttle valve and
tends to draw it closed. This action is opposed by a
governor spring which is attached to the valve shaft
through a cam ribbon and cam. By adjusting the pull of
this spring, the governor valve can be made to remain
open, and then closed at a predetermined engine speed.
Adjustment of the spring pull is accomplished by changing
the number of spring coils operating by turning the ad­
justment cap.
F ig . 1 G - Diagrammatic View of Governor for 6 -C y lin d e r Engine
MAINTENANCE AND ADJUSTMENTS
Adjustments
All governors are calibrated and adjusted in assembly
to insure accurate control of the maximum engine speed
of the model vehicle for which it is intended. However,
there will be occasions when minor adjustments are re­
quired to satisfy local conditions where the truck is
operating.
To adjust a governor for higher speed, turn the adjust­
ing cap "C " (fig. 2G) counter-clockwise or to the left: for
lower speeds turn adjusting cap "C” clockwise or to the
right. One' turn on the adjusting screw will change the
speed approximately 300-400 rpm or 4-5 mph.
F ig . 2 G - Governor Adjustment
STABILIZER (NON-CHEATING)
PISTON AND ROD
GOVERNOR
THROTTLE VALVE
ADJUSTING
CAP
GOVERNOR
SPRING
ADJUSTING
SCREW
ADJUSTING
SCREW
BUSHING
CAM
CAM RIBBON
CHEVROLET TRUCK SERVICE MANUAL