Poly Vinyl Chloride? (Just messing with you brother.
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I have seen many PCV arrangements on these trucks as well. Some of them are a bad idea in my opinion. If I were to rig mine with a PCV, I would rig it as similar as possible to a more modern inline six.
I believe that it is important to have the vacuum applied to the top of the valve cover to remove the water vapor which is known to rise to that location.
The vented valve covers on the '54 and earlier engines serve a dual purpose.
1) While underway on the open road, fumes are sucked out via the downdraft tube. This air is replaced through the vents in the valve cover.
2) While at low speeds or idle, fumes (water vapor mostly) rise to the top of the engine and are allowed to escape via the vents.
Folks have written about filling the vent holes and adding a vented cap which has filter material in it. When they removed the valve cover after driving for a significant amount of time, they discovered creamy goop on the underside of the valve cover. This would be indicative of the accumulation of water vapor which had no way to get out.
Carl
I'm somewhere in the middle of adding a PCV valve to my 1955 235. The more I read on the subject the more questions I have. If you adapt the road draft tube to accept a PCV valve and plumb it over to the intake manifold, does the additional air from the crankcase cause a lean mixture condition? In my case, I have an unvented valve cover with a filtered oil fill cap. Perhaps it's such a small amount of air that it doesn't have a noticeable affect on the engine's efficiency.
To remove moisture from the valve cover area, an open hose from the valve cover to the air cleaner coupled with the addition of a PCV valve should accomplish that, right? That probably works well with an oil bath air cleaner, but what about a paper element air filter?
Does it matter where the PCV valve is located, crankcase or valve cover? It seems that we addressing two main issues: crankcase gases and moisture. Of course, both are harmful to the service life of our stovebolts.
I'm sure there are reasonable answers to my questions and hopefully all of you can straighten me out on this. Otherwise, the time-tested road draft tube may just continue to reside on the 235............ I don't notice much coming out of the draft tube, but after the truck has been driven and parked for a while, there's an oily sheen on the garage floor, not a puddle just a sheen.
