Like everybody says, no sealer, but also FLAT and CLEAN. Do not over tighten the screws. Most leaks are the result of someone over tightening the screws. You can sometimes true up warped surfaces by laying a large pc. of fine grit sandpaper on a hard flat surface (like glass) and rubbing the gasket surface on the carb around in circles on the sandpapper. This meathod lets you see what is flat and what is not. Of coarse this only works if the carb does not have anything which sticks up past the gasket surface. Then clean the surface with a little solvent and screw together, but don't over tighten.
