All Other Models
- Remove carburetor from engine. Separate carburetor main body and throttle body. Using a hacksaw, cut through limiter shell (from cap end) 0.27" (7 mm) on GLC models (except Wagon) or 0.47" (12 mm) on all other models. See Fig 1 . Remove and discard limiter shell, mixture spring and mixture screw.
- Install new limiter shell with flat portion facing up. To install new mixture screw, tighten screw lightly and ensure it is fully seated. Back screw out 3 turns on B2000 models and 4 turns on all other models for preliminary adjustment.
- Reinstall carburetor with new gaskets and warm engine to normal operating temperature. Connect exhaust gas analyzer. Switch off all accessories.
- On Federal B2000 models, disconnect air cleaner-to-reed valve hose at reed valve port. On Calif. B2000 models, disconnect air by-pass valve-to-check valve hose at check valve and plug check valve port. On all other models, disconnect air control valve-to-check valve hoses at check valves and plug check valve ports.
- On all models, adjust idle speed to idle set specification using throttle adjusting screw. See Mixture Adjustment specifications. Using mixture screw, set idle speed to highest obtainable RPM.
- Using throttle screw, set idle speed to idle set specification. Turn mixture screw clockwise until lean drop specification is obtained. See Mixture Adjustment specifications.
- Check CO concentration. If less than 1%, turn mixture screw counterclockwise 1/2 turn (1/4 turn on B2000 models). Reconnect air hose and check curb idle speed. After adjusting idle mixture, install blind plug in limiter shell.IDLE MIXTURE ADJUSTMENT
Application Idle RPM Lean Drop RPM GLC Man. Trans 880 850 Auto Trans. (1) 1030 1000 GLC Wagon Man. Trans 830 800 Auto. Trans. (1) 1030 1000 B2000 Federal 670 650 Calif. 620 600 (1) Auto. Trans. in "N".