2x4s tunnel wedge and PCV

[1blackbb66]

Generally alot of what has been said here is correct, but lets get down to basics.
A functional PCV system is just as important in keeping the engine clean as it is in keeping the air we breath clean. (although most greeners would have a heart attack if they saw the HC and CO numbers our exhaust blows, but thats a whole other story) All you need is a single PCV valve that is correct for the engine type and size you are running. Wherever you place it (base of carb, inline, at the valve cover) it should ALWAYS draw from the passenger side valve cover. The reason for this is that most all engines (at least the ones we are dealing with) rotate clockwise (viewed from the front) and this rotation of the crank generally causes the air in the crankcase to move over and up to the passenger side valve cover. We want to take advantage of this natural flow in removing the blow-by gases. There should be a good full coverage baffle at the connection point to prevent oil splash and oil vapor being drawn into the valve. On the drivers side valve cover, there should be a good breather cap with a hose running to the air cleaner. There should be a good baffle under this cap as well. Make sure the hose connects at a point down stream of the filter as we want to draw filtered air into the crankcase. This cap doubles as the oil fill in most applications. Any ports, fittings, breathers, oil fills etc in the intake manifold should be plugged or capped so they don't leak. Those purists with 427's can leave the oil fill/breather in the manifold in place if they want, just make sure in dosen't leak air. If your system is set up properly and your getting oil all over the place, it's because something is leaking. Fix the leaks! There is a lot of oil flying around under the covers and if you don't have good seals, it's going to get out.
The PCV system never draws a vacuum on the crankcase. It's purpose is simply to draw the volatile compounds that vaporize from the oil, moisture and blow-by gases out of the engine to prevent sludge and air pollution. When the engine is under heavy load, there usually will be positive pressure in the crankcase due to excessive blow-by. This is not a problem because during this condition the excess blow-by is simply pushed up the hose attached to the breather cap and drawn into the carburetor. If the engine is badly worn, there will be blow-by pushed up this hose most of the time which can end up oiling down the inside of the air cleaner. I doubt anyone with a Cobra would let their engine get that bad.
If you are running fuel injection, I do recommend and oil seperator or filter for the PCV hose. The reason is that these manifolds run "dry" and on engine shut-down residual crankcase fumes tend to run up the PCV hose and collect and "coke" in the manifold which gunks things up and can foul the throttle valve and idle bleed valve.
So that's it. As always, the KISS method works best.

Ray