Cold air intake?
Well since you mentioned the hood, lol, I think for racing you would be better of to put an appropriate scoop on and seal the carb from the engine bay completely only drawing fresh cooler air from outside.
I had considered fabbing a cold air intake on my street (soon to be street/strip) car, but I got to thinking about the tubes, they would still get warm from the engine bay temps and still draw warmer air as opposed to outside air.
I could be way off base here, and I'm just thinking out loud, but I think the cold air intake would be pretty functional at more constant speed.
I'd be interested in other assessments on the subject.