Crankcase Pressure

[HandOverFist]

Originally Posted by Ron Gusack

If you have the valve cover connected to the fuel pump block off I don't think you're doing anything. They see the same pressure. I use manifold vacuum through the base of the carb and run a vacuum gauge to measure pan vacuum. It's not great but I do pull about 5 inches at the starting line. That's with both crank seals in the correct way.

Ron - The valve cover is vented to atmosphere...the crankcase only in a torturous way. I only configured a more direct route.

Btw, the above images do not show that a breather is used on the passenger side cover. No breather/sealed on the driver side.

[mike britt]

Secondary air injection, and as Glenn pointed out, not legal for stock.

[Bobby Fazio]

I only have one breather on the passenger side of my 5.0 and no breather on the driver side valve cover. Difficult to get anything to fit on drivers side valve cover because upper plenum is in the way. I have tried open breather and have tried connecting it to the throttle body like factory. I also have the PCV valve coming out the back of the block and have tried sending that to the throttle body, sending it to the upper plenum, and just plain blocking it off. I still haven't figured out the best scenario for a stocker and I still burn some oil occasionally. Leakdown shows up fine. At the risk of sounding like a fool, are you supposed to block off PCV when you run breathers or can you run breathers along with pcv? I'm thinking that sending unmetered air back into an EFI system without the computer knowing may not be as good as a Carb system.

[Eman]

PCV system always has a way to breathe. it pulls fresh air in thru the breather as it pulls fumes/pressure out of the engine into the manifold/plenum. Factory the breather tube goes to the air filter so it always gets clean air.

[Bobby DiDomenico]

Originally Posted by Bobby Fazio

I only have one breather on the passenger side of my 5.0 and no breather on the driver side valve cover. Difficult to get anything to fit on drivers side valve cover because upper plenum is in the way. I have tried open breather and have tried connecting it to the throttle body like factory. I also have the PCV valve coming out the back of the block and have tried sending that to the throttle body, sending it to the upper plenum, and just plain blocking it off. I still haven't figured out the best scenario for a stocker and I still burn some oil occasionally. Leakdown shows up fine. At the risk of sounding like a fool, are you supposed to block off PCV when you run breathers or can you run breathers along with pcv? I'm thinking that sending unmetered air back into an EFI system without the computer knowing may not be as good as a Carb system.

Bobby, on a Buick Grand National the passenger side valve cover oil separator/breather is connected by hose to the turbo intake which is after the air flow meter. The PCV into the intake. IIRC there are two kinds of PCV valves, normally open and normally closed, depending on the system and their location in it. On a Boss 351 for example (I remember the valve having suction at idle) the drivers side valve cover is connected to the PCV valve and the passenger side to a little filter in the air cleaner. The system sucking thru the PCV at high vacuum/low rpm, at higher rpm that closing as intake vacuum drops and it then drawing vapors out thru the valve cover into the air cleaner to the carb. As long as you can keep oil away from the suction openings it should be OK?