The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post

Longhorn Man · 12-14-2006, 05:17 PM

One one valve cover, you should have the PCV (Positive Crankcasr Ventilation) valve. On the other velve cover, either a tube going to the inside of the air filter, or a breather that is open to the elements. (The former is better, but seldom used in performance aplications)
The valve sucks acidic fumes caused by blow by, and as a natural byproduct of the combustion process, and it puts it into the intake charge, where it is burned with the incoming intake charge. This also removes condensation too. On top of that, any positive pressure inside the crank case...which can, and will blow out gaskets, is just placed in the intake charge as well, and a negitive pressure (vacume) is left in there whicvh helps improve ring sealing.
This is one emissions control item that is well worth the time and effort, and has no performance issues that I am aware of.
From an emissions/legal stand point, I think all (light duty) trucks since 69, and all cars since 65 are required (per federal law, regardles if your state enforces it) to have this... not that this matters to 75% of the ppl on here...just a FYI on that part. (info is for gas powered engines, not diesels)

12-14-2006, 05:17 PM	#10
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: Intake Gasket or Head Gasket? One one valve cover, you should have the PCV (Positive Crankcasr Ventilation) valve. On the other velve cover, either a tube going to the inside of the air filter, or a breather that is open to the elements. (The former is better, but seldom used in performance aplications) The valve sucks acidic fumes caused by blow by, and as a natural byproduct of the combustion process, and it puts it into the intake charge, where it is burned with the incoming intake charge. This also removes condensation too. On top of that, any positive pressure inside the crank case...which can, and will blow out gaskets, is just placed in the intake charge as well, and a negitive pressure (vacume) is left in there whicvh helps improve ring sealing. This is one emissions control item that is well worth the time and effort, and has no performance issues that I am aware of. From an emissions/legal stand point, I think all (light duty) trucks since 69, and all cars since 65 are required (per federal law, regardles if your state enforces it) to have this... not that this matters to 75% of the ppl on here...just a FYI on that part. (info is for gas powered engines, not diesels)