Quote:
Originally Posted by JSeery
A PCV by definition is a closed system that uses engine vacuum to pull air out of the crankcase. Believe what you are referring uses the air cleaner intake source for a PCV that draws the air from a fitting on the air cleaner via a oil filler cap on the valve cover. The suggested approach posted here is the reverse of that setup, it is using the slight vacuum within the air cleaner to draw air out of the crankcase without the use of a PCV valve.
An issue with this approach, to me, is you are pulling unfiltered air into the crankcase!
Back to the original post, are you sure you are using a correct PCV valve, one that is compatible with a flathead? Are you sure it is working correctly? The low vacuum you are seeing at idle would indicate it is not working properly. The valve should block the vacuum source at idle.
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The early '60s pcvs
were open, with the air intake "open" to the engine compartment. The later closed systems did run filtered intake air from the air cleaner by using a modified fill cap on a valve cover, like the Chrysler style some on this thread are using. But the ventilation used engine vacuum acting on a pcv,
not road draft.
The flathead pictured is modified '35-'48, different from an 8BA, and not a good way to plumb a pcv on the early V8s. However, creating any vacuum on a stock 8BA fill cap could result in pulling unfiltered dirty air up the road draft and into the engine-not good