Quote:
Originally Posted by 39 Deluxe
Agreed, crankcase will not be vacuum, especially considering how leaktight most of our flatties are.
PCV uses vacuum in the intake tract to vent positive pressure from the crankcase and direct it to the combustion chamber. PCV valve only opens at high vacuum conditions (i.e. idling, decel). It does not create a vacuum "leak" per se, as it is regulated by the design of the PCV valve itself. My real world experience is that the PCV system does not have a significant effect on manifold vacuum at idle, nor does it seem to have much affect on idle speed or mixture.
PCV on a flathead, good idea to eliminate draft tube "steam" and oily vapor smells. I wouldn't expect any other improvements.
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Yep, but it darn sure doesn't increase manifold vacuum!
