Originally Posted by dabnis
It would appear that short of up grading the valve system the advice of MMO & lead additives may be about all one can do? If it runs well, maybe take a compression test once in a while, change oil often and hope for the best. It was my experience that valve related problems come on somewhat gradually so it shouldn't just quit running all of the sudden?
The lead substitute does work. I think amazon has it in bulk. Do a compression check to make sure everything is OK and then do routine maintenance. Also use premium fuel with no alcohol. Add a fuel stabilizer which means the fuel will not go stale on you for a year. Gasoline with alcohol is only good for several months. If you do need valve work, get a IHC (International Harvester) Cub tractor block and rebuild it if the engine has direct salt water cooling (no heat exchanger) because of corrosion and possible cracks. This is an L head engine which means the valves are in the engine block. Use the original crankshaft as it is has had machine work to match to the marine transmission. Parts are available on the internet.