Chevrolet 10 1971 Series Chassis Service Manual page 188

ENGINE 6-10
Fig. 18— Tune-Up Decal
H_ the Combination Emission Control
CAUTIO N:
solenoid screw (fig. 17) is used to set engine idle
or if the solenoid is adjusted out of limits as
specified in Section 6M, a decrease in engine
braking may result.
• 250 and 292 Cu. In. (Single-Barrel Carburetor)
Disconnect " Fuel Tank" line from Evaporation
Emission vapor canister.
Disconnect the distributor spark advance hose
and plug the vacuum source opening.
Adjust carburetor speed screw to obtain 550 rpm
with transmission in neutral.
SOLENOID SCREW.
If the Combination Emission Control
CAU TIO N:
solenoid screw (fig. 17) is used to set engine
idle or if the solenoid is adjusted out of limits
as specified in Section 6M, a decrease in engine
braking may result.
Reconnect " Fuel Tank" line to vapor canister and
reconnect distributor spark advance hose.
• 350 Cu. In. (Four-Barrel Carburetor)
Disconnect " Fuel Tank" line from Evaporation
Emission vapor canister.
Disconnect the distributor spark advance hose and
20 and 30 Series Vehicles with Gasoline Engines
1. With engine running at operating temperature, choke
•
DO NOT ADJUST
•
20
Gas (LPG) Engines
1. With engine running at operating temperature, choke
•
•
plug the vacuum source opening.
Adjust carburetor speed screw to obtain 600 rpm
with transmission in neutral and air conditioning
"OFF" . DO NOT ADJUST SOLENOID SCREW.
If the Combination Emission Control
CAU TIO N:
solenoid screw (fig. 17) is used to set engine
idle or if the solenoid is adjusted out of limits
as specified in Section 6M, a decrease in engine
braking may result.
Place fast idle cam follower on second step of fast
idle cam, turn air conditioning "OFF" and adjust
fast idle to 1350 rpm with transmission in neutral.
Reconnect " Fuel Tank" line to vapor canister and
reconnect distributor spark advance hose.
valve in fully open position, parking brake on and
drive wheels blocked - adjust idle speed and mixture
as follows (See " Tune-Up Decal Figure 18):
250 and 292 Cu. In. L6 and 307 Cu. In. V8
Disconnect the distributor spark advance hose and
plug the vacuum source opening.
Turn air conditioning "ON" .
Turn mixture screw(s) in until lightly contacting
seat, then back screw(s) out four turns.
Adjust carburetor speed screw to obtain 600 rpm
with manual transmission in neutral; 530 rpm with
automatic transmission in drive.
Adjust mixture screw(s) equally in to obtain 550
rpm with manual transmission in neutral; 500 rpm
automatic transmission in drive.
Reconnect distributor spark advance hose.
350 (250 hp.) and 402 Cu. In.
Disconnect the distributor spark advance hose and
plug the vacuum source opening.
Turn air conditioning "OFF" .
Turn mixture screws in until lightly contacting
seat, then back screws out four turns.
Adjust carburetor speed screw to obtain 650 rpm
with manual transmission in neutral; 550 rpm with
automatic transmission in drive.
Reconnect distributor spark advance hose.
and 30 Series Vehicles with Liquid Petroleum
valve in fully open position, parking brake on and
drive wheels blocked - adjust idle speed and mixture
as follows (See " Tune-Up" Decal Figure 18):
250 and 292 Cu. In.
Disconnect the distributor spark advance hose and
plug the vacuum source opening.
Turn mixture screw in until lightly contacting seat,
then back screw out four turns.
Adjust carburetor speed screw to obtain 600 rpm
with transmission in neutral.
Adjust mixture screw equally in to obtain 550 rpm
with transmission in neutral.
Reconnect distributor spark advance hose.
350 (250 hp.) Cu. In.
Disconnect the distributor spark advance hose and
plug the vacuum source opening.
Turn air conditioning "OFF" .
Turn mixture screw in until lightly contacting seat,
then back screws out four turns.
Adjust carburetor speed screw to obtain 600 rpm
with transmission in neutral.
Reconnect distributor spark advance hose.
10-30 CHEVROLET TRUCK SERVICE MANUAL
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