I have a 1966 Model 122 Cub Cadet with what seems to be the original Kohler K301AS 12 HP engine on it. It has battery ignition in it. Everything I have read in the Kohler Service Manual says that the timing marks on the fly wheel should be a "T" for top dead center, -AND- an "S" or "SP" for the 20 degrees before top dead center ignition timing mark. The fly wheel on this particular engine only has one, completely unlabeled mark on it; there is no T, S or SP notation on the fly wheel at all ... just this one unlabeled mark. From the way the points move and the piston stroke, it would appear that this is the 20 degrees BTDC mark. Has anyone out there ever seen a Kohler 301 engine with just one unlabeled mark on the fly wheel? Can I assume that the one, unlabeled mark is at 20 degrees BTDC?