[Rev]

Personally, I've never seen the need for one. I do run an after market (Performer) Al. intake with some exhaust through the intake, but no "heat riser" valve that shunts more exhaust through under the carburetor when cold. The carb does have a vent that prevents pressurizing the float bowl. I'd bet it's something else causing the problem. Also, how hot do you mean? Shouldn't let it get over, say, 200 F, IMHO.

Rev