The points gap on a Merc 40 4hp is .020
The older model mercury outboards, with maker points, should have a 0.020" gap setting.
.035 spark .020 points
.017" to .019"
On most lawn mowers there is no timing - they have the flywheel set, as long as the shear pin is in place, it will put the magnet by the coil at the proper time to fire. The points are run by the gap (you set the gap on the points) and the pin pushes the points open at the proper to fire. The only setting you have to do is the gap on the flywheel to the coil and the gap on the points.
The maker points on the 4.5 hp Mercury outboard, are set at 0.020 in.
0.035
.035
I don't think you will find points on a '94
According to the Haynes guide the gap is .054 inches
The maker points in a 1967 model, 110 Mercury outboard, are gapped to .020 in.
20 to 25.000 points 16 to 18.000s