Yes it matters. Your engine needs a closed crankcase breather system, to continuously get rid of moisture and blow-by gasses. Moisture in the oil pan combines with hydrocarbons to form acids that attack your bearings.
but additionally, every street carb I have ever seen, has a port on it for that system, and the carb is calibrated to be working with that system. This is your idle-air bypass. If you eliminate it, you will have to introduce that idle air somewhere else, usually by increasing the curb-idle opening. This puts your throttle valves too far up the Transfer slots, and makes the engine run rich. In compensation, the mixture screws are screwed in too far, which leans the tip-in, sometimes causing a hesitation. So now everything is all crossed up. In compensation, the timing is advanced, the throttle closed and the mixture screws brought back on line. But with this compensation come two new problems; 1) the power-timing is advanced a like amount, and you may be putting the engine into detonation, and 2) you may put the engine into detonation at any time, any rpm, with just a little too much throttle. Detonation is bad news, usually breaking the pistons or shattering the plugs. The fix for this is running premium fuel, possibly needlessly costing you hundreds of dollars a year.
If you have a performance cam, it often needs all the bypass air you can find. The PCV system is the first and easiest place to go looking for it.
At heavy loads the engine naturally produces more blow-by, and the PCV system gets overloaded. At this time the valve cover breather will work in reverse, as a pressure relief. If it is not plumbed to the airbox, or somewhere else, it will puke oil vapors onto the valve cover and make a mess.
If you are a streeter,on the basis of reducing or eliminating acid formation alone, your engine needs the PCV to be operational.
Ok, I may have exaggerated the carb adjustments a little, but the end result is the same; your streeter needs an operational PCV system.
