1988 Johnson/Evinrude "CC" 40 thru 55 Models Service Manual, Page 67Get this manual
INote the engine with with the proper flushing adapter not run Run the engine test wheelDo propeller or for the adjustment1Connect timing light to the No1 cylinder2Start and run the engine to minimum of 5000 RPM in FORWARD gear with timer base fully advanced3The engine timing mark must align with appropriate mark on the flywheel gridMaximum Spark Advance 35A50
Maximum Spark Advance Adjustment
4 Stop the engine to prevent contact with rotating partsLoosen the timing adjustment screw nutTurn the adjustment screw in or out as necessary to correct the timingOne turn clockwise retards timing about and one turn counterclockwise advances timing about 105Tighten the nut and recheck the timing adjustmentAdjust the Engine Idle Speed 1The boat and engine must be in the water under normal operating conditions with the correct propeller installedThe boat's movement must be unrestrainedThe boat must not be tied to dock or trailer2Start the engine and allow it to reach normal operating temperature3Check idle RPM in FORWARD gear with an accurate tachometer