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The points should gap at .012 to .016 inches (.3 to .4 mm) at their widest point. Turn the crank shaft and watch the points open, and measure them when they're at their widest. If they're not right, loosen the screws and use a flat-tip screwdriver to get the right gap.
The F mark is used to find WHEN the points begin to open. As you turn the crankshaft, the one set of points should just start to open when you hit the F mark. If it doesn't you have to adjust the timing adjustment plate by loosening screws and prying the plate with your screwdriver. Do this for the 1-4 contact points, and repeat for the 2-3 points.
In order to find when the points just start to open, you can use very thin paper (cigarette paper works good). Slip the paper between the points, and turn the crank sloooowly. When you can pull the paper, the points are just starting to open.
