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I just installed new ford motorsport valve covers. It says in the instructions that this is a closed system. One cover has a place for pvc valve the other has a closed plug and a cap with a hose going to air filter. My question is my old covers had a breather cap where the plugged one is now should I used old breather or the new plug? What is the purpose of running hose to breather on the new plugged cap if it is plugged at valve cover? the engine is a 1973 or 1974 there are no emissions on engine egr valve ect. Will using breather affect operation or is closed system better? Thanks for the info.
First off, it's called PCV as in Positive Crankcase Ventilation.
Either way will work, although the hose to the air cleaner is better. The 'breather' will probably allow some dirt into the engine. You don't want that if you can help it at all.
The PCV valve sucks condensate, gasoline vapors, and other bad stuff out of the engine. All this stuff has to be replaced with fresh air, and thats where the breather/pipe to the aircleaner, comes in. You either need the breather to filter engine compartment air being sucked into the engine, or you can use the hose on the aircleaner, which sucks air already filtered by the aircleaner element into the engine.