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6C-52
1977 PONTIAC SERVICE MANUAL
SHIFT
Fig. 6C-93 M4MC Carburetor Identification
I N T E I W I L
VENT
SLOT
SEAT
V I L V E
SPRING
Fig. 6C-94 M4MC Float System
On cars equipped with air conditioning, turn A/C "on"
and disconnect electrical connector at A/C compressor
clutch. Open throttle momentarily to ensure solenoid plunger
is fully extended. Adjust solenoid screw to specified rpm. Re-
connect A/C compressor clutch electrical connector and turn
A/C "OFF".
Manual transmission
-
adjust idle stop screw to specified
rpm.
10. Unplug and reconnect hose from vapor canister and
EGR valve.
11. Shut off engine and remove tachometer.
Carburetor Adjustments
Refer to Figs. 6C- 102 thru 106 for carburetor adjustment
procedures and specifications.
IDLE AIR BLE
M
C A ~ S T E R
\
PURGE
IDLE DISCHARGE
TUBE
HOLE
OFF-IDLE
OPERATION
3071
Fig. 6C-95 M4MC ldle System Exc.
X
Series
VI
Code
L
ldle Mixture
See Idle Mixture Adjustments at the end of this section.
Choke Fresh Air Modulator
-
VIN Engine Codes P
&
z
Functional Check
1. Cool engine off until air cleaner assembly is below 50"
F.
2. "TEE" vacuum gage between fresh modulator and
choke stove.
3. Start engine. Vacuum gage should read more than 5
inches mercury of vacuum. If not, replace modulator or
locate vacuum leak.
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