Back in the day there weren't as many options for carburetion. you couldn't get much bigger, so you simply added an extra (or 2 or 3...)! These days you can get a bigger carb. There are intakes for the old stove bolts that you can put a big four barrel on. Usually a single bigger carb will out perform multiple smaller carbs if the CFM's are the same. (Although some people will argue otherwise) Hot Rod recently ran an article about comparing performance between single and multi-carb setups, this article will confirm my points.
FACT: Single carbs will NEVER look as cool as multiples.
