Chevrolet 70 1969 Series, Shop Manual

Page: 709 / 913

E N G IN E 6-38
Rocker Arm
Rocker Arm Return Spring
Actuating Lever
Pump Body
Arm and Lever Pivot Pin
Oil Seal
Oil Seal Retainer
Diaphragm and Seal
Retainer Spring
Diaphragm Spring Seat
Diaphragm Assembly
Valve Body and Fuel Cover
Valve Body and Fuel Cover
Screws
Pulsator Diaphragm
Pulsator Cover
Pulsator Cover Lock Washer
Pulsator Cover Bolt
____________ T-794
Figure 1— Fuel P u m p C o m p o n e n ts (T y pic al)
CARBURETOR OVERHAUL
(MODEL WWC FOR 401M AND 478M ENGINES)
Repair kit is available which contains all parts usually
requiring replacement in an average overhaul. Refer to
applicable parts book for repair kit part numbers.
To properly overhaul carburetor, special tools should be
used by mechanic thoroughly familiar with carburetor ov­
erhaul procedures. Tools are listed at end of manual.
DISASSEMBLY
Disassembly consists of separating the carburetor into
its three basic sections (fig. 1), namely the air horn (upper
section), main body (center section), the throttle body
(lower section), and the disassembly of each of these sec­
tions.
NOTE: Throttle valves in open position extend
below the throttle flange, therefore care should
be exercised to avoid damage to the valves.
1. Disconnect fast idler link accelerating pum p link.
2. Remove three short screws, identification tag, and
choke control bracket, then remove the four long
screws and separate the carburetor assembly into
three basic groups shown in Figure 1.
NOTE: The “special screw" shown in Figure 1
is located near center of carburetor. Use care to
avoid loss of pump check ball (12, fig. 3) when
handling main body assembly.
AIR HORN DISASSEMBLY
Key num bers in text refer to Figure 2.
1. Remove pum p piston (19) and spring (18), then re­
move spring from piston.
2. Using small wood block and suitable open end
wrench, pry power jet piston (17) assembly out of air
horn.
3. Remove cotter pin (1), then remove retainer (2), and
double-ended lever (4) together with spring (3), and
bushing (5).
4. Remove nut and lock washer (12 and 11), then re­
move lever (10) from choke shaft.
5. Remove nut and lock washer (15 and 14), then re­
move lever (13) from pum p shaft (16).
6. Remove the screws (8) attaching choke plate (7), then
remove plate from choke shaft (6). W ithdraw shaft (6)
from air horn.
MAIN BODY DISASSEMBLY
Key numbers in text refer to Figure 3.
1. With diagonal cutter-type pliers, remove secondary
high speed bleeders (4) from cluster (6), then remove
screws (5) attaching cluster (6) and remove cluster as­
sembly and gasket (7).
2. Invert m ain body (14) and catch check ball (8) as it
drops out of main body passage.
3. Remove fuel valve needle, seat, and gasket (13) from
body (14).
CHEVROLET SERIES 70-80 HEAVY DUTY TRUCK S H O P M A N U A L