Those are idle air tubes. At idle, the throttle butterflies should be completely closed and ALL air for the engine passes through those tubes. There's an adjuster in the idle air distribution tower on top of the manifold.
their more of an air line than a fuel line, no reenforcement or cords. should be able to get at any autoparts store. if you need the idle adjust block, I have one, my 74 has carbs and some po left it on.