Aluminum is a great heat transfer medium - so good that many companies use it for radiators. Next, most Performer intakes have an exhaust gas passage though there are versions without. If it has that EGR/exhaust passage set up, that adds even more heat to the carb. The boiling point of gasoline can be as low as 100 degrees F up to 400 degrees all depending on the additives. A phenolic spacer is the first step with a heat shield as a follow up - there are others, ceramic insulated versions, besides the usual and conventional Edelbrock, Holley and Mr Gasket