Chevrolet Corvette 1963 Repair & Tune-Up Manual page 61

56 TUNE-UP AND PERFORMANCE MAINTENANCE
a time until the maximum idle speed is ob-
tained. Then set the idle speed screw to:
Standard engine (180 hp) M.T.-800 rpm,
A.T.-550 rpm; Optional engine (210 hp) M.T.-
900 rpm, A.T. (low altitude) 750 rpm, A.T.
(high altitude) 650 rpm.
11. Turn in each screw (lean) Vs turn at a
time until the idle reaches the following rpm:
Standard engine (180 hp)-M.T.-700 rpm,
A.T.-500 rpm. Optional engine (210 hp)-800
rpm, A.T. (low altitude), 600 rpm for A.T.,
high altitude.
12. Reset the idle speed to specification.
13. Reconnect the vacuum hoses and in
stall the air cleaner.
1978-80 IDLE SPEED
This procedure applies only to those models
which DO NOT have the computer con-
trolled emissions system. Vehicles having the
computer system have 13 screws retaining the
air horn of the carburetor; vehicles without
the computer system have 9 screws retaining
the carburetor air horn. Also, computer
equipped vehicles do not have the familiar
vacuum advance unit installed on the distrib-
utor, as the spark advance is controlled by
the computer.
CAUTION: // your vehicle has the com-
puter emissions system, DO NOT attempt
to adjust either the idle speed or mixture,
as the fuel system calibration could become
severely upset.
Run the engine to normal operating tem-
perature, A/C off, die purge hose at die va-
por canister and the vacuum hose at the EGR
valve disconnected and plugged. Place the
manual transmission is Neutral and the auto-
matic transmission in Drive. NOTE: Make
sure the parking brake is on and the drive
wheels are safely blocked before the
transmission is placed in Drive.
Without A/C
1. Turn the idle speed screw to achieve the
rpm specified on the underhood specifica-
tions decal.
With A/C
1. Turn the idle speed screw to the lower
of the two idle speeds listed on the under
hood specifications decal.
2. Turn the air conditioning on.
3. Disconnect the A/C compressor lead at
the compressor (two-wire connector).
4. Open the throttle slightly to allow the
solenoid plunger to extend fully.
5. Turn the solenoid screw to adjust the
engine speed to the higher of the two speeds
listed on the specifications decal under the
hood. Use the higher idle speed, NOT the
fast idle speed specification.
6. Reconnect the A/C compressor lead.
1978-80 IDLE MIXTURE
Changes in the idle systems of these models
make it impossible to properly adjust the
mixture without the use of a propane enrich-
ment system, not available to the general
public.
In some 1978 and all 1979-80 models, the
idle mixture screws are sealed within the
dirotde body of the carburetor. Idle mixture
adjustments should be left to the professional
technician with the proper equipment and
experience.
1981-84 IDLE MIXTURE
Idle speed and mixture are controlled strictly
by the computer emissions system. Do not
attempt to adjust the idle speed or mixture as
these functions are controlled by the com-
puter.
NOTE: For all throttle body injection ad-
justments, see the Fuel Injection section.