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FUEL SYSTEM
6C-39
AIR
MCDULATOR
I
COOL AIR
<
HEATED AIR
OSE
HEATED
'
-\CYLINDER
HEAD
EXHAUST
GASES
Fig. 6C-7
1
Choke Fresh Air Modulator
-TO
SECONDARY
VACUUM BREAK
-TO
MAN1 FOLD
VACUUM
Fig. 6C-72 Secondary Vacuum Break Thermal Vacuum
Switch
-
SVEB-TVS
damage.
2. If choke or linkage binds, sticks or works sluggishly,
clean with United Delco Choke Cleaner X-20-A or
equivalent. Use cleaner as directed on can. If cleaning does
not correct, replace binding parts.
3. Visually inspect carburetor to be certain all vacuum
hoses are connected. Inspect hoses for cracks, abrasion,
hardness or signs of deterioration. Replace or correct as
necessary.
4. Make sure vacuum break diaphragm shafts are fully
extended when engine is off. If shafts are not fully extended,
replace vacuum break assembly. Start engine, primary
vacuum break diaphragm shaft should fully retract. If unit
fails to retract, replace vacuum break assembly.
5. With engine at normal operating temperature, the
SVB-TVS must be open. Check by applying either engine
vacuum or auxiliary vacuum to the inlet port on hot TVS and
checking for vacuum at the outlet. If there is no vacuum,
replace the TVS.
6. Apply a vacuum to the vacuum break diaphragm and
observe for movement to the full travel position. Due to the
orifice in the unit, it will take up to 20 seconds to reach full
travel. If full travel is not obtained, the orifice is plugged and
the diaphragm must be replaced.
ADJUSTMENTS
Idle Speed Adjustment
Refer to Vehicle Emission Control Information label on
vehicle for latest certified specification information.
1. With engine at normal operating temperature, choke
full open, and air conditioning OFF, connect a tachometer
to engine.
2. Set parking brake and block drive wheels.
3. Disconnect and plug hoses from vapor canister and
EGR valve.
4. Disconnect A/C compressor clutch connector.
5. Start engine and position transmission in PARK or
NEUTRAL.
6. Disconnect and plug distributor vacuum advance
hose.
7. Set ignition timing at specified rpm
8. Unplug and reconnect distributor vacuum line.
9. Adjust idle speed:
10. With A/C
-
Adjust idle stop screw to specified rpm
Turn A/C "ON" and disconnect electrical connector at A/C
compressor. Open throttle momentarily to ensure solenoid
plunger is fully extended. Adjust solenoid screw to specified
rpm Reconnect A/C compressor electrical connector.
1 1. Unplug and reconnect hose from vapor canister and
EGR valve.
12. Shut off engine and remove tachometer.
13. Connect A/C compressor clutch.
Procedure For Using Carburetor Choke Valve
Angle Measuring Gage
1. Choke valve angle measuring gage 5-26701 tool may
be used with carburetor on or off engine. If off engine, place
carburetor on holding fixture so that it will remain in the
same position when gage is in place.
2. Rotate degree scale until zero (0) is opposite pointer.
3. With choke valve completely closed, place magnet
squarely on top of choke valve. See Figure 6C-73.
4. Rotate bubble until it is centered.
5. Rotate scale so that degree specified for the particular
adjustment is opposite pointer. See Figure 6C-74.
6. Adjust the choke linkage to center the bubble. This
completes adjustment.
Carburetor Adjustments
Refer to Figs. 6C-75, 76 and 77 for cabruretor
adjustment procedures and specifications. The choke value
angle gage is the preferred method for making all carburetor
external adjustments. The following procedure can be used
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