Re: 1962 Evinrude Lark IV smoke in engine
Are you sure that is the problem? Is the old one missing or badly rotted, or what? Yes, that will allow exhaust to bubble up under the hood when running at idle at the dock, but when under way the exhaust is buried in the wake behind the boat.
The most common reason for smoke getting under the hood is the 202591 o-ring being left out when changing a water pump. It goes on top of the water pump housing. There are two more on the drive shaft tube extension if it is a long shaft. And of course the tube extension has to be in there too.
Other possible smoke sources are a torn bellows hose at the exhaust relief outlet, and trying to run it in a barrel with the hood on.