1993 Johnson Evinrude "ET" 40 thru 55 Service Manual, P/N 508283, Page 45Get this manual
Maximum Spark Advance
I"N'=J Run the engine with he correct test propellerDo not run
the engine with regular propeller or flushing adapter for this adjustment1Connect timing light to the top cylinder's spark plug leadMark the flywheel timing grid at 19 BTDC2Start the engine and allow it to reach normal operating temperature3Run the engine at no less than 5000 RPM in FORWARDThe engine's timing pointer must align with 19 BTDC on flywheel's timing gridf81 '" 4Stop the engine to prevent contact with rotating partsAdjust the length of the spark control rodas necessary, by removing the forward socket from spark lever CDf815Rotate the socket in clockwise direction to advance timing or in counterclockwise direction to retard timingTwo revolutions equal approximately one degree of timingf816Install the spark control rod on the spark lever CD, and verify maximum spark advance following Steps thru 3Idle 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