Vacuum Pump Adjustment

The idling MIXTURE adjustment, Figure 66, is determined by turning the adjustment screw out until the engine operates roughly. Turn the screw in until the engine idles smoothly. The correct adjustment is with the screw approximately 1-1/2 turns open.

Figure 66 Lo ad or Power Jet Adjustment

A preliminary load adjustment has been made as part of your dealer's pre-delivery service; however, it may be necessary to readjust the carburetor load setting when the engine is operating under load.

To obtain a starting point, operate the engine under no load at full governed engine speed. Be sure the engine is up to the correct operating temperature. Turn the load adjustment screw in, Figure 66 (clockwise) until the engine misfires and power falls off; then turn it out (counter-clockwise) trntil the engine runs smoothly. Turning the adjustment out produces a richer mixture, turningit in produces leaner mixture. The correct setting is with the adjustment approximately 2-3/4 turns open.

Place the engine under load and carefully observe how it reacts. If there is backfiring through the carburetor, loss of power, or the engine tends to stall when the load is applied, it indicates the setting is too lean. Turn the load adjustment screw out(counter-clockwise) not more than 1/8 of a turn and again try the engine under load. Continue to do this until the engine pulls into the load smoothly.