Chevrolet isn't the only engine manufacturer that determined that long exposed intake runners on carb engines were more efficient in getting the fuel/air mixture into the cylinders when they were hotter than the ambient temp.
They all do....
On the old VW opposed 4 cylinder boxer engines the long intake manifold runner(s) has exhaust heat circulating through a jacket that encloses the intake manifold where it splits directly under the carb and it's full time heat, not regulated like on these old Stovebolt inline 6's.
Should we expand the convo to discuss why many manufacturers of carb engines would preheat the incoming air on a cold engine?
Same principle.
