My carb ices up here in the PNW. I get frost, and infact, the truck will quit outright. Lots and lots of moisture in the air out here, and ice in the carb to boot.
Here's a pic of my frozen rochester. This happens almost everyday in the winter, unless I plug the truck in, as the block heater, warms the intake and carb up. I'm about 120 feet above sea level in my driveway. The carb will freeze up after about 5 minutes of running when everything is cold.
http://i221.photobucket.com/albums/dd45/HomeCrafter/IMG00014.jpgRight about now, the truck quits, then you sit there and listen to the radio for about 5 minutes, and fire it up. The manifold warms up the carb.
My model T would freeze up like this, until I installed the factory hot air pipe. Old Henry knew what time it was.