there are no marks on the cam gears. the two diamond shape plates on the front of the cams have a large and small hole in them. there is a special tool (long bar with pins) that lines up these holes. the bolts on the cams get loosened and the gears "poped" free on the cams so they cam spin free while setting belt tension. the cam gears are conic and not keyed to the cams, only the diamond plates are keyed to the cams.