Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-42794--1, Page 39Get this manual
Timing, Synchronizing and Adjusting Firing Order Throttle Primary Pickup Maximum Timing Advance Throttle Secondary Pickup Full Throttle RPM Idle RPM Timing Indicator Location Electric Start Models (H Figure a") Manual Start Models (Hb") Figure Alternate Firing
THROTTLE PRIMARY PICK-UP ADJUSTMENT
1Connect timing light to No1 (top) spark plug
2Start engine and shift into forward gear3Advance engine speed until specified throttle primary pickup timing mark lines up with timing indicator, then adjust turn buckle (Han Figure 3, earlier models) or adjustment screw ("b" Figure 4, later models) so that throttle cam ("c Figure 5) is just touching carburetor throttle lever ("dFigure 5) when specified primary pickup is lined up with tim ing indicator