Do we need a PCV System?

[cudabob496]

Do we have to have a PCV system, if we change our oil regularly?
Isn't venting the crank case through the valve cover breathers good enough?

[Bullitt-]

Benefit of PCV is to create negative pressure in crankcase, pressure causes oil leaks & blow by, so unless you like oil leaks install one.

[cudabob496]

But I have valve cover vents on both valve covers.

[Bullitt-]

But I have valve cover vents on both valve covers.

  You need negative pressure, see my edit

[cudabob496]

  You need negative pressure, see my edit

OK, but I'm trying to figure how to get negative pressure in the crankcase, with breather vents on both
valve covers.  Seems the vents will pass a lot more air than the little vacuum port on the side of my carb.
I'm tired of the PCV system sucking oil into my intake. Am building a PCV oil separator, but now thinking
of disconnecting the PCV line instead.

Maybe the "tree huggers" demand it.  We are putting junk into our intake, which certainly ain't
making more power.

[Bullitt-]

I guess that's why the factory puts a breather on one side & the PCV on the other. Could you not do the same?

[cudabob496]

I guess that's why the factory puts a breather on one side & the PCV on the other. Could you not do the same?

Have PCV line on P/S valve cover, and vents on both valve covers.

[Bullitt-]

Have PCV line on P/S valve cover, and vents on both valve covers.

I can see where having a vent/breather on the same side allows a easy path for air to be sucked at probably higher velocity than intended, you also would not get the benefit of negative pressure in the block...try taking the breather off & plugging the hole on the side with PCV.. just might solve the issue.

[cudabob496]

I can see where having a vent/breather on the same side allows a easy path for air to be sucked at probably higher velocity than intended, you also would not get the benefit of negative pressure in the block...try taking the breather off & plugging the hole on the side with PCV.. just might solve the issue.

The main issue I'm having now is oil getting into the PCV line, causing the engine to use more oil than it should.
Think I'm gonna remove the PCV line from the valve cover, block it off to the carb, and install another breather where
the PCV line hole is now. That way I'll have 3 vents to keep crank case pressure from getting too high, and maybe solve
my oil consumption issue.

[HP_Cuda]

The one question you have to ask yourself is do you want pressure buildup inside your motor?

Otherwise that pressure will come out via blow-by and a ton of white smoke.

[burdar]

Run a hose off of each valve cover and plumb them into the header collectors...or exhaust pipes.  The flow of exhaust will create a vacuum and pull vapors out of the crankcase. 

[HP_Cuda]

The only problem with using exhaust to ventilate is that you need to have straight through mufflers otherwise you buildup a nice pool of oil and can cause a muffler fire over time.

[burdar]

I've never heard of that before. Even a straight through muffler has perforations in the pipe that would let oil collect in the bottom of the case. I would think the exhaust temp when fully warmed up would burn off the oil before it had a chance to collect.  If you had that much oil pooling in a muffler, I think you'd have major engine issues.

[HP_Cuda]

You'll see when you go to buy those exhaust evac systems they warn you to only use on a straight through muffler.

But hey anyone can do whatever they want. I was actually thinking of using one but after buying some expensive flowmasters I decided to go the separator route and it's worked great.

[cudabob496]

The one question you have to ask yourself is do you want pressure buildup inside your motor?

Otherwise that pressure will come out via blow-by and a ton of white smoke.

How can pressure build up if I have 3 breathers total on the valve covers?