I am thinking of plugging the old pvc and trading the breather for a little K&N filter. I took a class with a very knowledgable guy, Dema Elgin, and if I recall correctly, he said having a vacuum in the crankcase helps keep the rings against the cyls and keeps oil around the rings to also aid in sealing. Im not sure if that applied in a race engine or stock. My slant is pretty raced out and I want the best sealing possible. anyone heard something like that? or should I go with the K&N and just have ventilation instead of a vacuum?

Im no expert, but I thought the purpose of the pvc valve was the first step in emission control. It pulls the noxious gases out of the crank case and reburns them by putting that air back thru the carb.
I would think that if you put enough vacum into the crank case to "help seal the rings" it would suck out all the oil. I do know you want to vent the crank case so you dont build up pressure because this can work against you.
I would hope someone else will answer you better than I have.
Frank

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Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

The PCV, if working properly, maintains a partial vacuum in the crankcase. There are other systems out there as well, but for most engines and drivers the PCV system is the most effective and least expensive option. An open crankcase is the least desirable way to go.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

Your PCV applies vacuum to your crankcase in most situations. The breather lets air in.

At WOT when there is little vacuum the breather lets crankcase fumes out.

If you remove the PCV and just have a breather you will defeat an excellent system for venting your crankcase.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Definitely keep the PCV system intact. There's no way anything will be better with just a breather (whether it's K&N's garbage or somebody else's breather). The PCV system is the most effective way of maintaining low pressure in the crankcase, and offers a whole wealth of benefits and zero drawbacks in terms of engine operation, economy and cleanliness.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

There is some truth that vacume in the crank case does produce horse power over a open beather system. And ring seal with added windage in the crankcase is the cause of this happening(loose of power) . So vacume does help this alot. This is why some race engines have added vacume pumps to gain even more Ringseal & windage reduction.

Unless you have a major blowby (or high boost forced induction) problem it would probably be best to keep the PCV system. Even in a high boost engine a hybrid crank vent system is ussauly the comprimize between a vac system that cant handle the extra pressure & extra breather systems to handle the excess blowby that needs to excape.

If you have a aftermarket air cleaner that doesnt have a breather hookup for the valve cover just use the PCV still hooked up as ussaul & use a breather (K&N or other) on the other side.


Jess