my 302 has valve cover with pcv on right valve cover and where oil cap on left valve cover there is a tube on side under cap open that draws a lot of vacuum. Curious to see if I can plug it off and engine be ok with that vacuum blocked off. Having brain fart and don't remember. I know new valve cover don't have that opening, only pcv valve on one. If correct I think that that port went to original bottom of air breather with filter inside. Just needing alittle reassurance on blocking that port because I'm putting new valve covers on! Thanks
Is your set up something like one of these? I have used both the plain cap and the cap with a hose going to the air cleaner with equal success. If I understand the PCV system correctly, the left side is fresh air intake, and the PCV on the right side is the "exhaust" back to the intake. It would seem like having a vacuum on the left intake side is a good thing, and blocking it off not so much. I prefer the look of the plain cap, which is what I'm running now.
If the plain cap has a filter, that setup is OK, otherwise you are drawing dirty air right onto the valve train and down into the engine. On my 521 I run a sealed vacuum system rather than a vented one. You can only get away with that if you have very low levels of blow by on the rings. Otherwise you will blow oil out of your seals, a problem you will likely encounter if you plug the vent. If you plug the vent, you also need a backflow preventer so that a backfire doesn't pressurize your crankcase, again, blowing oil past the seals.
yes the valve cover itself has the vacuum under the oil fill cap. I think I will put a breathable oil fill cap on....ty
ty my cap does not have filter and is tube fed right into valve trane. I will put fltered cap on and block tube until I get new valve covers.
