I was swapping the carb on my 1978 Dodge motorhome (440 w/ factory thermoquad intake) and I noticed that there was a big open threaded hole in the bottom of the right side of the manifold. There was also another smaller smooth bore hole on the left. What are these for? These can't possibly help the flow of air. Should I plug them? I'm trying to squeeze as much gas mileage as I can out of this thing.

 

Do you already have holes for the lines going to valve cover pcv's if not may be for them! If not Plug'em!