Both Steve's give important information. I have a 'free breathing" setup
in my 1963 Rambler and in the interest of getting rid of said fumes
connected a quick fix PCV valve to a "convienient" tap on the end of a long
straight 6 manifold. It did lean out because there was not an equal
distribution of the "air leak" the valve creates. Vacuum assisted devices do
not leak (well, in theory a very small amount of extra air is provided on
activation - if you want to split a hair) and can often be used on a runner.
Even there, on a runner, at a very low idle, they MAY pulse and depending on
the purpose could possibly affect the intended function.
In addition to the PCV benefits Steve L. presented I wonder (it is just a
thought) if the oil vapors can also be beneficial to valve seat life???
Tom Witt B9470101
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