Chevrolet 70 1969 Series, Shop Manual

Page: 713 / 913

E N G IN E 6*42
1. Throttle Body 4. Shaft Retaining Washer
2
.
Throttle Plates 5. Shaft Bearing Assembly
3. Throttle Shaft 6. Seal
ings unless inspection indicates n eed for n ew
bearings, since bearings will be d a m a g e d in re­
m oving.
Drive out each bearing (2, fig. 6) using suitable driver,
then remove seal from bearing bores in throttle body. L u­
bricate new seal and install seal in bearing bores with seal
lip pointing outward. Use a driver which will apply pres­
sure near outer edge of bearing casing when installing
bearings. Press each bearing squarely into bores in
throttle body with nam e on end of bearing outward. Press
bearings in until outer edge is approximately 0.040 - inch
below outer surface of throttle body.
NOTE: Do not remove lubricant from new bear­
ings.
ASSEM BLY
ASSEMBLY OF THROTTLE BODY
Key numbers in text refer to Figure 6, unless otherwise
indicated.
NOTE: If throttle shaft bearings were not re­
placed, apply engine oil to each bearing as­
sembly.
1. Insert throttle shaft (7) through throttle body (8),
using care not to dam age seal (3) when installing
shaft.
2. Place retainer washer (1) in groove in throttle shaft,
then move shaft endwise until washer is seated in
counterbore in throttle body.
3. Refer to m arks made on throttle plates (4) at disas­
sembly and locate throttle plates at throttle shaft in
respective bores. Loosely install throttle plate screws
(9) with heads at bottom (fig. 7). Rotate throttle shaft
to close plates, then check retaining washer which
must be a m inim um of 0.002-inch in from outer sur­
face of throttle body as shown in Figure 7. Hold
plates closed and tighten throttle plate screws securely.
NOTE: Operate the throttle shaft and check
plates which must not bind in any position and
must close tightly.
4. Install throttle shaft driver (6) at end of throttle shaft.
5. Install idle mixture screws and springs (11 and 10),
turning screws in lightly against seats, then backing
each screw out one complete turn.
6. Install throttle driver assembly on throttle body. Spe­
cial screw is used at bottom hole and serves as stop
for idle speed adjusting screw.
GOVERNOR UNIT ASSEMBLY AND INSTALLA­
TION
Key numbers in text refer to Figure 5, unless otherwise
indicated.
1. Using new gasket (16), install governor housing (17)
on throttle body (15). Tighten four screws (9) firmly.
Screws have lock washers which must be in place and
in good condition.
2. Refer to Figure 4 and install spring anchor at the No.
3 position as shown. Attach link (8, fig. 4) to gover­
nor lever as shown and retain with hairpin type lock.
Insert link through hole in housing and attach lever to
throttle shaft with screw and lock washer (3, fig. 4).
Install governor spring (5, fig. 4). Spring hooks to pin
on lever and anchor screwed into housing.
3. Place spring (18) in housing, then assembly di­
aphragm assembly (19), outer diaphragm (20), and di­
aphragm cover (21) at housing. The sleeve on di­
aphragm assembly (19) must fit over link (5) when as­
sembled. Install screws (22) to retain parts.
4. Use new gasket (3) and install cover (2) on housing.
Install choke control holder (23) on throttle body.
ASSEMBLY OF MAIN BODY
Key num bers in text refer to Figure 3.
1. If they have been removed, install fuel passage plugs
(15).
2. Install main metering jets (11) using thin wall socket.
Install power jet (9) and gasket (10).
3. Place pu m p inlet check ball (12) in center channel in
pum p cylinder, and place pu m p discharge check ball
(8) in center passage in main body.
4. Use new gasket (7) and install main body venturi
cluster (6' in main body, attaching cluster with three
screws (5). Install two secondary high speed bleeders
(4) in cluster.
5. Insert float axle (3) through float lever, and locate
float (1) in bowl with axle engaged in guide. Set
spring (2) in place.
6. Install fuel valve needle, seat, and gasket (13).
7. Set float level. Figure 8 shows use of float level
gauge.
ASSEMBLY OF AIR HORN
Key numbers in text refer to Figure 2.
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK S H O P M A N U A L