Carburetor Adjustments
- With engine at normal operating temperature and ignition timing set to specifications, set idle speed to specifications by turning throttle stop screws equal amounts.NOTE: Spitfire has a single carburetor, so balancing carburetors per step number 2 is not required. See Tune-Up Chart for proper specifications.
- With suitable air flow meter, check and adjust carburetor balance with engine at specified idle speed.
- Install a combustion analyzer and observe combustion efficiency. If readings are slightly outside permitted range, adjust carburetor trim screw(s) equally.CAUTION: Trim screw is no an ordinary mixture adjustment screw. Adjustment is so fine that only a meter can detect results of adjustment.
It is important to avoid prolonged idling when checking air fuel ratios. After each 3 minute idling period, run engine at 2000 RPM for 1 minute.