Chevrolet Light Duty Truck 1973 Service Manual page 346

6 -1 0 ENGINE
SINGLE-BARREL
IDLE M IXTURE SC REW
CEC S O L E N O ID
HICLE EMISSION CONTROL INFORMATION
G EN ER A L MOTORS CORPORATION
fcNTS WITH ENGINE AT NORMAL OPERATING TE M P ,
: IN STALLED. AND DISTR VACUUM LINE DISCONNECT
UM LINE WHEN ADJU STMENTS ARE COMPLETED
BLOCK DRIVE WHEELS
f'FUOM VAPOR CANISTER.
2. S fT DW ELL AND TIMING' AT SPECIF IED RPM
3. ADJUST CARBURETOR SOLENOID SCREW TO SPECIF IED RPM
4. WITH TRANSMISSION IN PARK OR NEUTRAL. ADJUST FAST ID LE SCREW TO SPECIF IED
SPEED ON TOP STEP OF CAM. VAC. SPARK CONN. FOR AUTO TRANS
5. RECONNECT FUEL TANK HOSE TO VAPOR CANISTER
6 IDLE MIXTURE PRESET AT FACTORY DO NOT REMOVE CAPS
7. IF CARBURETOR IS REPAIRED OR IDLE MIXTURE SCREW CAPS HAVE BEEN REMOVED. RESET IDLE MIXTURE BY USING
*/4 TURN RICH FROM LEAN ROLL METHOD. IN STALL REPLACEMENT ID LE MIXTURE SCREW CAPS PROCURED FROM DEALER.
8 REMOVAL OF MIXTURE SCREW CAPS AND ALTERIN G TO OTHER THAN SPECIF IED ID LE MIXTURE SETTIN G
MAY VIO LATE FEDERAL AND /OR CALIF ORN IA AND OTHER STATE LAWS.
.( C O N FO R M S II
/^W R ENGINE EXHAUST EM ISSION CONTRO L INFORMATION
G EN ER A L MOTORS CORPORATION
MAKE ID LE SPEED (CARBURETOR SCREW OR SOLENOID SCREW) AND TIM ING A DJUSTM ENTS AT SPECIF IED RPM WITH ENGINE AT NORMAL
OPERATIN G TEMP, CHOKE OPEN. AIR COND OFF. AIR CLEANER IN STALLED. D ISTR. VACUUM LINE DISCONNECTED AND PLU GGED
F ITTIN GS WHEN SETTIN GS ARE COMPLETED. SET PARKING BRAKE AND BLO CK DRIVE WHEELS. PUT TRANS IN PARK OR NEUT. FOR ALL SETTIN GS.
ID LE MIXTURE PRESET AT FACTORY DO NOT REMOVE CAPS. REMOVAL OF MIXTURE SCREW CAPS AND ALTERIN G TO OTHER THAN SPECIF IED IDLE
MIXTURE SETTIN G MAY VIO LATE FEDERAL AND/OR SOME STATE LA WS. IF CARBURETOR IS REPAIRED OR ID LE MIXTURE SCREW CAPS HAVE BEEN
REMOVED, RESET IDLE MIXTURE BY LEAN DROP METHOD. IN STALL REPLACEMENT ID LE MIXTURE SCREW CAPS PROCURED FROM DEALER.
I REG U LA TIO N S APPLICAIIE T l
Fig. 17—Tune-Up Decal
On Heavy-Duty vehicles - C-K-P20 (except C-K20
suburban) and C-P30 - adjust carburetor Idle Speed
Screw to obtain 600 rpm with automatic transmission in
"Park" and manual transmission in neutral.
TW O -B AR REL
IDLE MIXTURE SC REW S
IDLE SPEED (S O L E N O ID ) SC R E W
Fig. 16—Idle Speed and Mixture Screws
[ ]
qm
DWELL
TIM ING ( BTDC@ RPM )
SPARK PLUG GAP
SOLENOID SCREW (RPM)
FAST IDLE SCREW (RPM)
IDLE MIXTURE SETTIN G •/« TURN RICH FROM LEAN ROLL
CA LIFO R N IA III
RECONNECT ALL
LEAN DROP IDLE MIXTURE
f»» G A SO LIN E WHO MW P U TT E N G IN ES_ _ _ _ _ _ _ _ _ _ _ PT NO. 330S64
On Light-Duty Vehicles - C-G-K10 and C20 Suburban -
adjust Idle Stop Solenoid (turn solenoid body, using hex
nut) to obtain 600 rpm with automatic transmission in
Drive - 900 rpm with manual transmission in neutral.
On Light-Duty vehicles, disconnect the Idle Stop
Solenoid electrical lead. Adjust low idle screw (located
inside the solenoid hex nut) with screw on low step of
cam, to obtain
Drive and manual transmission in neutral - reconnect
Idle Stop Solenoid electrical lead.
.Reconnect "Fuel Tank" line to v va^$^ canister and
reconnect distributor spark advanceHfegase^
• 350 Cu. In. (Four-Barrel Carburetor)
On Light-Duty vehicles, disconnect "Fuel Tank" line
from Evaporation Emission vapor canister.
Disconnect the distributor spark advance hose and plug
the vacuum source opening.
On Heavy-Duty vehicles, adjust carburetor Idle Speed
Screw to obtain 600 rpm with automatic transmission in
J 7
"Park" and manual transmission in neutral.
On Light Duty vehicles, adjust Idle Stop Solenoid (turn
solenoid body, using hex nut) to obtain 600 rpm with
automatic transmission in Drive; 900 rpm with manual
transmission in neutral.
On Light-Duty vehicles with automatic transmission,
reconnect distributor spark advance hose. Adjust fast idle
FOUR-BARREL
IDLE M IXTURE SC RE W S
IDLE SPEED (S O L E N O ID ) SC REW
rpm - automatic transmission in
LIGHT DUTY T R q p ^ E t & IC E MANUAL