Yes, I had the same problem with this carb on a 340 in my Challenger. It only was a problem in Atlanta during the summer months. Get a phelonic carb spacer. It will block a lot of the heat and help.
http://www.summitracing.com/parts/edl-8711?seid=srese1&gclid=CLmHzcG41McCFVM7gQodDWAEiQ