Chevrolet 70 1969 Series, Shop Manual

Page: 359 / 913

ENGINE FUEL SYSTEM 6M -32
Figure 21 —Adjusting Buffer
Screw
b. Remove high speed spring from high speed
plunger and add or remove shims as required to
establish the desired engine No-Load speed.
Figure
22—Checking
Governor
Cap (Typical)
N O T E : Shims are available in .010" and .078"
thickness. For each .010" in shims added, the en­
gine speed will be increased approximately 10 rpm.
c. Replace high speed spring on high speed
plunger and assemble the spring assembly into
governor housing. Install spring retainer into gov­
ernor housing and tighten securely.
d. Start engine and recheck engine No-Load
speed. Repeat steps a, b, and c, as necessary, to
establish the No-Load speed.
L O W SPEE D SPRING A D J U S T M E N T
With the maximum No-Load speed properly
adjusted, the idle speed may be adjusted as follows:
1. With engine running at normal operating
temperature and with buffer screw backed out to
avoid contact with the differential lever, turn the
idle speed adjusting screw until the engine idles
at the recommended idle speed (refer to fig. 20).
The recommended idle speed is 450-500 rpm
but may vary with special applications.
2. Hold idle screw and tighten lock nut.
3. Install high speed spring retainer cover.
B U F F E R S C R E W A D J U S T M E N T
With the idle speed properly adjusted the buf­
fer screw may be adjusted as follows:
1. With engine running at normal operating
temperature, turn buffer screw in (see fig. 21), so
that it contacts the differential lever as lightly as
possible and still eliminates the engine hunting.
N O T E : Do not increase engine idle speed more
than 15 rpm with the buffer screw.
2. Recheck maximum No-Load speed. If it has
increased more than 25 rpm, back off the buffer
screw until increase is less than 25 rpm.
G O V E R N O R GAP A D J U S T M E N T
With the engine at operating temperature, the
governor gap may be set as follows:
1. With the engine stopped remove two bolts
and withdraw governor high speed spring retainer
cover.
2. Back out buffer screw until it extends 3 /4 ".
3. Start engine and loosen idle speed adjusting
screw lock nut and adjust idle screw to obtain an
idle speed of 450 rpm.
4. Stop engine and remove governor cover and
engine rocker covers.
5. Start and run engine at a speed between 800
and 1,000 rpm by manual operation of the differ­
ential lever, as shown in figure 22, and check gov­
ernor gap between low speed spring cap and the
high speed spring plunger.
C A U T IO N : D O N O T O V E R S P E E D E N G IN E .
6. With the engine operating at a speed of 800
to 1,000 rpm set the gap between the low speed
spring cap and the high speed spring plunger at
.0015" by adjusting the gap adjusting screw in the
operating shaft lever (bellcrank lever).
7. Hold gap adjusting screw; tighten lock nut.
8. Recheck gap and readjust if necessary.
9. Stop engine and reinstall governor cover.
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK SH O P M A N U A L