If the new copper gasket (as Gord suggested) on the inlet fitting doesn’t fix the leak, there is a known issue with Rochester “B” carburetors, where the top to bottom flange gasket leaks. Replacing the gasket usually doesn’t solve the issue. The flange is known to warp and a fellow ’bolter Jon G, has a post that shows how to straighten. Although not a easy fix, it will fix this issue. Here’s a
[LINK].
