Chevrolet Corvette 1963 Repair & Tune-Up Manual page 56

important that all tune-up instructions be
carefully followed to ensure satisfactory en-
gine performance and minimum exhaust pol-
lution. The different combinations of emis-
sion systems application on the different
engine models have resulted in a great vari-
ety of tune-up specifications. See the "Tune-
Up Specifications" chart at the beginning of
this chapter. Beginning in 1968, all models
have a decal conspicuously placed in the en-
gine compartment giving tune-up specifica-
tions.
When adjusting a carburetor with two idle
mixture screws, adjust them alternately and
evenly, unless otherwise stated.
In the following adjustment procedures the
term "lean roll" means turning the mixture
adjusting screws in (clockwise) from optimum
setting to obtain an obvious drop in engine
speed (usually 20 rpm).
NOTE: Due to the camshaft design of some
special high performance engines (350/LT.I,
427IL88,454/LS6, etc.) it is normal for these
engines to have a "lopey" idle.
1963-67 WITHOUT A.I.R.
NOTE: Adjust with air cleaner removed. 1.
Connect a tachometer and vacuum
IDLE MfXTURE
Carter WCFB idle mixture and speed adjustment
screws
IDLE MIXTURE /"
ADJUSTING SCREWS
Carter AFB idle mixture and speed adjustment
screws
TUNE-UP AND PERFORMANCE MAINTENANCE
| SPEED
DLE
SCREWS SCREW
IDLE
SPEED /
ADJUSTING SCREW
gauge to the engine, then set the parking
brake and shift the manual transmission into
Neutral, automatic into Drive.
2. Turn the idle mixture screw(s) in until
lightly seated, then back out IVz turns.
3. With engine running, adjust the idle
speed screw to obtain the specified rpm.
4. Adjust the idle mixture screw(s) to ob
tain the highest steady manifold vacuum at
the specified speed. If necessary, reset the
idle speed screw while adjusting mixture.
NOTE: On air conditioned models, the air
conditioner is turned on and the hot idle
compensator valve is held closed while ad-
justing idle speed and mixture.
5. Final adjustment should be made with
the air cleaner installed.
6. Remove tachometer and vacuum gauge.
1966-67 WITH A.I.R.
Adjust with air cleaner removed.
1. Connect a tachometer to the engine,
place manual transmission in Neutral, auto
matic in Drive.
2. Turn idle mixture screw(s) in until
lightly seated, then back out 3 turns.
HOLLEY4150
Holley 4150 idle mixture and speed adjustment
screws
ROCHESTER 4MV
Rochester Quadrajet idle mixture and speed ad-
justment screws
51