1997+ Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-826148R2, Page 49Get this manual
Specifications IGNITION SYSTEM Type Spark Plug Type (NGK) Spark Plug Gap Optional Plug (NGK) Spark Plug Gap Firing Order Models With (SN-0G589999Below) Idle Maximum BTDC 2500-5500 RPM (Not Adjustable) Models With (SN-0G590000Above) Idle Maximum Spark Advance Capacitor Discharge BP8H-N-10 0.040 in(1.0mm) BPZ8H-N-10 0.040 in(1.0mm) 1-2 BTDC (Not Adjustable) 25 BTDC BDTC Turn Clockwise After Contacting Throttle Plate