Buick LeSabre 1965 Service Manual page 120

3 - 4 4 4-BARREL ROCHESTER
ENGINE FUEL AND EXHAUST
where it no longer exerts any
spring tension on the choke valve.
The choke valve is in the wide
open position and the fast idle
cam is in the slow idle position
so that the fast idle screw misses
the cam completely. The throttle
stop screw now takes over in
determining curb idle speed.
h. Operation of Choke
Unloader
If the engine becomes flooded for
any reason, the choke valve can
be partially opened by depressing
the accelerator pedal to the full
extent of its travel. This causes
an arm on the throttle lever to
contact and rotate the fast idle
cam, which forces the choke valve
open.
i. Operation of Secondary
Lock-Out
The secondary section does not
have a choke valve in the air
horn. In order to prevent air
from entering the carburetor
through the secondary side during
the engine warm-up period it is
necessary to block the movement
of the secondary throttle valves
by means of the lock-out slot in
the fast idle cam.
CHOKE
ROD
Figure 3-47—Exterior Linkage
When the choke valve is in any
position except wide open, it holds
the fast idle cam up from its
lowest position. This causes a
lock-out slot in the fast idle cam
to engage a tang on the secondary
throttle shaft lever which pre-
vents the secondary t h r o t t l e
valves from opening.
When the choke is wide open the
lock-out slot of the fast idle cam
drops to its lowest position; the
secondary throttle shaft tang is
then free to move and the second-
ary valves can open.
3 - 1 9 DISASSEMBLY,
CLEANING, AND
INSPECTION OF
ROCHESTER
4-BARREL
CARBURETOR
1. Remove spring clip from up-
per end of intermediate choke
rod and disengage rod from choke
shaft lever. See Figure 3-47.
2. Remove clip from upper end
of pump rod and disengage rod
from pump lever. Remove horse-
shoe clip from upper end of pump
plunger.
3. Remove choke trip lever and
attaching screw. Disengage choke
lever and collar assembly from
choke shaft and disengage lower
end of choke rod from fast idle
cam. Then remove choke lever
and collar, and choke rod as an
assembly. See Figure 3-47.
4. Remove two choke valve at-
taching screws. Remove choke
valve from slot in shaft. Remove
burrs from choke shaft, then re-
move shaft from air horn.
5. Remove all air horn screws,
then c a r e f u l l y lift air horn
straight up from main body to
avoid damaging floats, pump
plunger, and vacuum power piston
which are attached to air horn.
6. Remove float hinge pin, float,
float torsion spring and needle
from primary side being careful
not to damage small spring. Then
remove inlet needle seat and gas-
ket. Remove fuel inlet strainer.
NOTE: Keep primary float sys-
tem parts separate from second-
ary float system parts.
7. Remove float hinge pin, float,
float torsion spring, needle, nee-
dle seat, and gasket from side
opposite pump (secondary). Then
remove needle seat strainer.
8. Remove pump plunger assem-
bly and boot from air horn.
Remove air horn gasket.
9. Remove power piston assem-
bly by compressing spring and
letting it snap repeatedly until
hammering action of power piston
drives staked retaining disk from
air horn. NOTE: It may be nec-
essary to remove burrs if heavy
staking is encountered.
10. Remove thermostat cover
screws and retainers. Remove
thermostat cover assembly and
gasket. Remove choke baffle
plate. Remove choke piston lever
screw and take choke piston, pis-
ton pin, connecting link, and lever
from thermostat housing as an
assembly.
11. Remove screws holding ther-
mostat housing to throttle body.
Remove thermostat housing and
gasket. Then remove intermediate
choke shaft, lever, and rod from
choke housing as an assembly.
12. Remove a t t a c h i n g screws
from cluster assembly on pump
side of c a r b u r e t o r (primary).
Then carefully r e m o v e cluster
assembly and g a s k e t . NOTE:
Keep primary main body parts
separate from secondary main
body p a r t s as they are all
different.
13. Remove both main metering
jets from pump side of main body.
See Figure 3-52. Remove power
valve and gasket.
14. Remove pump return spring
from pump plunger well. Remove
outlet check ball spring guide