Mine did the same thing, and recently I put a wooden spacer there to help. It helped out some, but not much. Even with the wooden spacer the carb is too hot to the touch once the engine is up to temp. No heat riser or anything. I'm thinking about using some fuel line insulation next to see if that will help. My fuel line runs cloe to the header on the passenger side, and is routed up very close to the front of the engine block before it ties into the carb.