Evidently you didn't read this posted by 1oldtimer. They even give you the number for the correct PCV.
A simple solution, run what ever hose size you can from the valve cover to the carburetor. In that hose, shove a solid plastic plug in to block all air flow. Buy a cheap set of NUMBER drill bits, start with the smallest bit and drill a through hole in the plastic plug. If it doesn't work, step up to the next bit and try again. Keep going till it works to your liking. You may have the vacuum, but it won't have the volume needed to clear the crankcase unless you run 3/8" line. There is a reason PCV and brake boosters have 3/8" or bigger lines.
Same reason fire nozzles are smaller then the actual hose, you need lots of volume to move stuff efficiently, you can't do that with a small hose.
I don't know... A fire hose has a huge pump behind it, that provides a ton of pressure and the smaller nozzle "concentrates" that into a focused stream. I don't think that analogy works for a PCV system that is vacuum based. To me it sounds more like a bottle neck, where the smallest orifice in the chain dictates the max throughput.
Controlled flow/metering for proper fuel balance. One does not fit all and what works on a sound engine may not work on a worn engine.
I agree, but that's beside the point, that the smallest orifice is always dictating the max throughput in any system, and not the huge hose you put behind (or before) that restriction.
That's kind of true, but not entirely. For instance a four barrel carburetor might have a circa 0.10" inlet valve, and will run okay at full capacity with a 5/16" fuel line but starve with a 3/16" or 1/4" line. I believe it's because you have to take into account the length of a pipe as well as diameter, so a very long pipe or tube has significant drag in it. I think there's lots of math involved, something Engineers have to deal with.
To follow up on on that point I will make an analogy here to the flow of electrical current (just remember that at some point all analogies break down, this isn't perfect, just an illustration). There is restriction in wire, and the longer the wire, the larger it needs to be to sustain current flow. You can get away with a smaller gauge of wire over a short distance that you cannot get away with over longer distance. The same with the vacuum hose, there is restriction in the hose itself. Though there is a small orifice in the pcv, you cannot use a hose with that same ID and maintain sufficient flow of air to completely evacuate the engine. The longer the hose, the larger the ID required to maintain sufficient flow of air. The length of hose required to make the run from the point where the pcv is installed to the manifold requires minimum of 3/8" ID to maintain sufficient air flow to evacuate the engine. The strength of the vacuum will not change, but the amount of air flowing will.
The Jalopy Journal
