2001 Mercury Mariner 50-60HP Factory Service Manual, Page 129Get this manual
TIMING, SYNCHRONIZING,ADJUSTING
2Place the outboard in "Forward" gear and check timing at idle "Retarded (If not within specification window, refer to Diagnostic Test Procedures Section 2A
aTiming Mark (Full Retarded) 3Slowly increase the engine RPM while watching the ignition timing marksThe timing should increase to the maximum timing specification "Full Advance" at approximately 6000 RPM(If not within specification window, refer to Diagnostic Test Procedures Section 2A