The 273 came with 2 barrel carbs. Later they came with a 4 barrel on a Commando Intake! However, the 4 barrel Commando came after the heads & intake marriage changed the angle for that union. So the 4 barrel Commando Intake I have will go onto the 318 I just got & the 273 will get the repaired original 2 Barrel Intake after I get it brazed!