A couple of things I forgot to mention. Check the top of the cam perifery down to the beginning of the reset bevel. If it is clean and 90 degrees to the face of the hammer it is not repeat not the problem. This is the only part of the cam that has anything to do with timing.
As to the correct positioning of the cam there is none unless it has a preground reset bevel then you align the top edge of the bevel at or about 90 degrees to the cutout flat in the hammer. The only dimensions to be concerned with is the pivot diameter is correct for the hole in the hammer and the major diameter of the cam is the same as the one you are replacing.
The cam is a circle and gets its camming effect from the angle on the hand surface it contacts and the increasing distance between the cam surface and hand surface as the hammer is rotated. I hope that is clearer than mud.
