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6C-12
1 9 7 7 PONTIAC SERVICE MANUAL
3. Disconnect and plug PCV hose from vapor canister.
4. Disconnect and plug vacuum advance hose at
distributor.
5. Start engine and position transmission in drive with
automatic transmission or neutral with manual transmission.
6. Check and/or adjust ignition timing.
7. Unplug and reconnect vacuum advance hose and
adjust idle speed.
8. Automatic transmission or manual transmission with
A/C
--
Adjust carburetor screw as specified above.
Disconnect electrical connection at W.O.T. air conditioning
override switch located on accelerator linkage bracket. Set air
conditioning to "ON" position. Momentarily open throttle
to allow solenoid plunger to fully extend. Adjust solenoid
screw to specified rpm. Reconnect air conditioning override
switch. Turn air conditioning " O F F .
9. Position transmission in neutral or park.
10. Adjust fast idle speed.
11. Unplug and reconnect PCV hose at canister.
12. Shut off engine and remove tachometer.
Carburetor Adjustments
Refer to Figs. 6C-19, 20 and 21 for carburetor
adjustment procedures and specifications.
L4-151 2-Port or 3-port Vacuum Delay Valve
-
Choke Vacuum Break Functional Test
1. Verify correct installation per vacuum hose schematic
Sec. 6 F or on vehicle emission control information label.
2. Then "Tee" a vacuum gage into the hose between the
VDV and the choke vacuum break.
3. When checking 3-port VDV's, disconnect the hose
between the VDV and the TVS at the VDV and cap the port
on the VDV.
4. Start the engine. Disconnect the vacuum hose at the
input to the VDV and hold a finger on the end of the vacuum
hose. The vacuum gage should read ZERO.
5. Re-connect the vacuum hose while observing the
vacuum gage.
The vacuum reading should not increase immediately,
but should rise slowly (taking about 40 seconds to reach
manifold vacuum).
6. If the vacuum rises too fast or too slowly, the VDV
is defective.
7. The maximum vacuum reading should be within 1
inch of manifold vacuum. If not, there is a leak either in the
VDV, vacuum break unit, or hose connection.
8. Re-connect vacuum hoses per vacuum hose
schematic.
L4-140 California and High Altitude Secondary
Vacuum Break TVS Functional Test (Fig. 6C-26)
The TVS can be checked on or off the vehicle. Verify
correct installation before and after test by referring to
vacuum hose schematic on vehicle emission control
information label.
On-Car Check
1. Allow engine to cool long enough for the engine
coolant temperature to be below 105°F. In warmer climates
this may require that the car be parked over night. If this is
not possible, remove the TVS from engine and follow the
off-car check.
2. Start engine and check for vacuum at port #3, there
should be no vacuum. If there is vacuum, verify that coolant
temperature is below 105°F. and recheck for vacuum. If there
is vacuum, replace TVS.
3. Let engine idle until coolant temperature is above
105°F.
4. Check for vacuum at port #3, there should be
vacuum. If there is no vacuum, check for vacuum at hose
connected to the
#
1 port. If there is vacuum at hose, replace
TVS. If there is no vacuum at hose, trace vacuum hose to
source, determine cause for no vacuum and correct as
necessary. Then recheck TVS.
Off-Car Check
1. With TVS out of car, cool TVS below 105°F. by
running cold tap water over it.
2. Apply vacuum to port
#
1. TVS should hold vacuum.
If it does not, replace TVS.
3. Warm TVS above 105°F. by running hot tap water
over it.
4. Apply vacuum to port
#
1. Vacuum should be present
at both ports #2 and #3. If not, replace TVS.
CARBURETOR REPLACEMENT
Removal
Flooding,
stumble
on
acceleration
and
other
performance complaints are, in many instances, caused by
presence of dirt, water or other foreign matter in carburetor.
To aid in diagnosis, the, carburetor should be carefully
removed from engine without draining fuel from bowl.
Contents of fuel bowl may then be examined for
contamination as carburetor is disassembled. Check filter.
1. Remove air cleaner and gasket.
2. Disconnect fuel and vacuum lines from carburetor.
3. On L4-140 disconnect choke water housing and choke
thermostat housing.
4. Disconnect accelerator linkage and electrical
connectors.
5. If equipped with automatic transmission, disconnect
downshift linkage.
6. Remove carburetor attaching nuts and remove
carburetor and solenoid assembly attachment.
7. Remove insulator gasket, air cleaner bracket and
flange gasket.
Installation
Fill carburetor bowl before installing carburetor. This
reduces strain on starting motor and battery and reduces the
possibility of backfiring while attempting to start engine. A
small supply of no-lead fuel will enable carburetor to be filled
and the operation of float and inlet needle and seat to be
checked. Operate throttle lever several times and check
discharge from pump jets before installing carburetor.
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