"There is no OEM gasket. I wish there was. I have tried to make one w/ caulk gasket material and indian head, but the 'lip' is 1/16" or less - too fragile. I agree - there should be a gasket in a marine environment. I am playing w/ trying to make one with silicone.
Be that as it may, every (2) months or so, my motor will misfire at higher RPM's - I remove the cap and see that the ignition contacts within the cap are 'fuzzy'. I clean it and am on my way.
My dizzy is located right at the seam / opening of my i/o cover - not an ideal location. There is a 1" lip to prevent rain water from getting in, but spray must make it's way in and voila moisture. For example, right now the (2) screws that hold the rotor in place are pretty rusted - one has a stripped phillips head and I'll have to crack the rotor off to get the screw off...
My mechanic says the 'fuzzy cap' has been an issue w/ many of these motors and although ideally it shouldn't happen, in reality there is a moisture problem. I know a couple of other guys who deal with it and just clean their old caps and re-install ( different model boats too )...
So, I'd love advice on this and also where I might buy a aftermarket cap/rotor without losing QUALITY.
The waxy water resistant stuff, is called 'cosmoline' - sounds like a good application, but some kind of mechanical gasket would be better. I do 665 lube the entire motor 2-3 times a season (7 months ).
BTW: The motor is 8-9 years old and looks new. I maintain it myself."