mumbling n grumbling at a stop light

What kinda carburetor gasket do you have under the carburetor? You should have a really thick one. It helps insulate the carburetor and keep the fuel from getting too hot and possibly boiling. If you don't have one, you might even get one like this with a shield on it.

http://www.summitracing.com/parts/mrg-3710/overview/

You would put the thick gasket on the manifold and that heat shield ^^^^^ on top of the thick gasket. Although as others have said, you will want to double check the tuning, that heat shield cannot hurt. I wouldn't put one together without some form of heat protection for the carburetor.