Working on a '67 225 Dauntless, the intake manifold has two ports (5/16"holes) that bring exhaust to the base of the carburetor. The guy that re-built my carb suggested blocking them off. Assume this keeps the carb at the right temp to preheat the fuel/air mix, right? Thoughts? If you have blocked them off what did you use? Here is pic of the exhaust ports (at pencil tip) I am referring to.