PCV VALVE NEEDED OR Can I use a breather?

[toofun]

Unless I am mistaken the PCV VALVE is used to vent the crankcase correct? It usually runs to the carb and plugs into the valve cover so I have to ask. Is it really needed? Could I substitute the PCV Valve with a breather instead and get rid of it? The less clutter the better but want to make sure it is not going to harm anything by doing this.

Thanks
Mark
TOOFUN

[Travis B]

You do need a pcv valve..I tried to run without one and it will usually seep past the breather and leak! My dad had a big block car with breathers only and it would blow the dipstick out of the tube!

I wouldn't recommend it!

[CAMAROBOY69]

I am also interrested in the answer for this. I usually run at least one PCV to the air cleaner (pass side) and on the driver side I put a breather. I have done this for at least 12 years with no problems on any cars or trucks. Once in a while oil will blow out of the breather though which I dont like. Depending on my revs.
Oh yeah I also tried one time a long time ago to plug both holes. Not good!! Oil everywhere from the pressure.

[6'9"Witha69]

Both. Refer to the other trhead you had about the Air Gap.

[Matt@RFR]

You do NOT need a PCV valve. Those of you who ran two breathers need bigger breathers if you're pushing dipsticks out and/or blowing oil out of the breathers.

Adam, when you had your PCV valve run to your air cleaner, that was wrong. The whole point of running one is to apply the vacuum that's in the plenum to suck oil vapor into the intake. It's not all that much, but I, personally, don't see much point in purposely putting oil in your combustion chambers when we do so much to keep it out.

Don't get this cofused with pulling vacuum in a crank case via dry sump pump or vacuum pump. Your plenum does have vacuum, but lacks the volume to add any perks that the aforementioned will.

The size and quantity of breathers you need depends on cid and rpm. And if you're pushing oil past two big ass breathers, you probably have some serious blow by issues.

How many 500+ci, 8500rpm race motors have you seen with a pcv valve?

[streetk14]

I agree that you probably don't NEED a pcv valve. I think for a street car, it is a good idea. It will help reduce crankcase pressure better than breathers alone, which will help to prevent oil leaks. I run a pcv valve on one side, and a breather on the other (with baffles in the valve covers).
Matt, I don't think you will ever see a race engine with a pcv valve, but that doesn't mean that they don't have their place. I'd assume that most 500+ ci 8500 rpm race motors are running a vacuum pump to reduce pressure and allow lower-tension rings to increase power. I think most would call this overkill on a street car.
-Andy

[RobM]

I think I’m going to run two pcv's into my header collectors.... this seems like a good middle ground between what’s good on street engines and race engines.... by the way a motor is powered by electricity not fuel!!!!! you have an engine!!! :geek: I’m sorry I couldn’t resist I just got grilled by one of my engineer friends on that one. :eek:

[tireman]

RobM,

I tried that, but it did not work because of back pressure in the exhaust. It might be because I only have 2 1/4" exhaust, but I think that system is meant for open headers.

I've been thinking about this:

http://www.gzmotorsports.com/street-pump-kits.html

[Matt@RFR]

Rob, from the Merriam-Webster dictionary:

MOTOR
Main Entry: 1mo·tor
Pronunciation: 'mO-t&r
Function: noun
Etymology: Latin, from movEre to move
1 : one that imparts motion; specifically : PRIME MOVER
2 : any of various power units that develop energy or impart motion: as a : a small compact engine b : INTERNAL COMBUSTION ENGINE; especially : a gasoline engine c : a rotating machine that transforms electrical energy into mechanical energy

ENGINE
Main Entry: 1en·gine
Pronunciation: 'en-j&n
Function: noun
Etymology: Middle English engin, from Middle French, from Latin ingenium natural disposition, talent, from in- + gignere to beget -- more at KIN
<snip>
4 : a machine for converting any of various forms of energy into mechanical force and motion; also : a mechanism or object that serves as an energy source <black holes may be the engines for quasars>
5 : a railroad locomotive


Andy, I agree 100%, I just think there's much better ways of going about venting crank case pressure....but I'm alittle off the deep end when it comes to things like this. :)

[RobM]

well then...I guess I should prove my engineer friend wrong! haha I only said that cause I had an hour long argument hours before that’s post about it with this guy :rolleyes5 thanks for the ammunition for proving him wrong! tireman i never thought about the back pressure problem I always assumed there was no back pressure right in the collector and all of the back pressure in the exhaust would be further down the system but i guess that makes allot of sense. has any one run a vacuum pump and power steering? i don’t like a mess of belts I don’t have serpentine so I’m wondering if any one runs a vacuum pump on a street car with power steering?