The load spreader bars that were originally used on Corvair air cooled engine valve covers make a huge difference in how well a stovebolt cover seals. They also prevent the distortion of the sheet metal in the area of the bolt holes. Clones of the Corvair spreader bars are available from most of the specialty auto parts people like JEGS and Summit. I like to use Permatex Super 300 brush-on sealer. It stays flexible and isn't nearly as messy as RTV and other tube type rubber sealers.
Jerry
This is what to use.
RTV is horrible, and is the worse stuff to clean off, and won't maintain a good seal unless all the surfaces are surgically clean, not even a finger print is allowed. I rarely use it.
