My 59 235 was missing the heat riser valve when I got the truck. It seemed to run well but had a few issues I thought were related to missing valve. I replaced the manifold with a working heat riser and indeed it ran better and no longer had the hard start when warmed up well. It also no longer showed frost on carb body at times. One time in about a thousand miles of use it iced the carb to the point I had to wait for the ice to melt from engine heat before it would re start. I am happy with the result of the repair.
