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.
Courtesy of MAZDA MOTORS CORP.
- 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. |
1030 |
1000 |
| GLC Wagon |
| |
Man. Trans |
830 |
800 |
| |
Auto. Trans. |
1030 |
1000 |
| B2000 |
| |
Federal |
670 |
650 |
| |
Calif. |
620 |
600 |