I MODEL 4MC CARBURETOR 6 S x The Model 4MC carburetor is basically the same as i described in the 1971 Service Manual with the following i exceptions l GENERAL DESCRIPTION OF CHANGES SLOW IDLE ADJUSTMENT A bottom seal fuel inlet nut is used to prevent possible 1 Engine at mi mai Opeming ipmpemuip Remove deterioration of the fuel inlet threads To accomplish this air deans discuimeci air cipanpi vacuum hose at the fuel inlet nut gasket has been moved from the outside intake manifold then plug Btting surface to the bottom of the fuel inlet nut threads The seal 2 Choke Open and ai conditioning Om being located at the bottom of the threaded section 3 Set parking brake and block drive wheels prevents envy rgrel frenpreachlng the threads whieh rnleht 4 ihiseonneci carburetor hose from vapor canister cause possr e etenora ion p ug hose r i The milled slots in the tips of the secondary metering 5 Disconnect distributor vacuum hose at distributor rods have been removed as they are no longer necesary and plug Two types ef idle eentrels are used e is 6 With dwell and timing properly adjusted it electrically operated idle stop solenoid and the other is a equipped wigi vacuum dciimdi di idle Solenoid vacuum operated vacuum actuator The purpose of both is adjust actimui Oi Sdieiidid to Obtain to maintain a slightly higher idle speed to control exhaust emissions The carburetor speed screw slow idle screw will DO NOT DISOONNRT SOLENOID OR VACUUM be adjusted at a lower RPM so that when the engine is AC i UATOR i turned off and the idle control becomes de energized the throttle valves close further to prevent dieseling Automatic i mis i m1S in drive Set to 650 Rm r Manual Trans Trans in neutral Set to 750 RPM 7 Athust carburetor screw to obtain ADJUsTM 5N If equipped with either idle solenoid or vacuum The adjustment procedures are the same as shown m et t r deertersize by dieeenneetins wire er the 1971 Senzice Manual however some of the adjustment l h9 Plug Vewum hese specifications have changed and because of the addition of the throttle closing device the slow idle procedure has WITH IDLE SOLENOID OR VACUUM r wig d ACTUATOR Automatic Trans Trans in park set to 550 RPM Manual Trans Trans in neutral set to 550 RPM ADJUSTMENT SPECIFICATION xgl IOUT IDLE SOLENOID OR VACU UM Float Lever l 4 UATOR Pump Adjustment rmrerl lore 3 s ghoke Cod Lew i20r Automatic Trans Trans in dnve Set to 600 RPM st mi c 230 Airvgije Sdnsiipot 050 NOTE Idle mixture screws have been preset at Choke Cod Adjustment index the factory and capped D0 NOT REMOVE CAPS V B ak a7g g250e 230 8 Connect vacumn actuator hose or idle solenoid 7 wire connect distributor vacuum hose connect 7042251 4 21 Sn carburetor hose to vapor canister connect air 7042252 cleaner hose and install air cleaner l 7042953 275 I Unloader 200 udp Air Valve rgclrout 03gn peru uumremm l u tr mem Secondary pening 07 AirV lve spore ZEEEE E 350 Cu In 1 2 Turn us cum 2 4 rum 2 ieee neun Q Slow Idle See Slow Idle Adjustment rue recess sstuuun ucuo u A Fast Idle I I00 RPM 2 seuuu ciuur me fEf T3 ZZ ef Z ZC Dashpot 060 Q u il i g g 1 g E E Y E c ru 1c 7 Denotes a new specification for 1972 sH 1 Model 7