25THRSS

I was wondering if there are any adverse effects of taking the pcv valve off and putting a push in breather in its place and plugging the line to the tbi? Has anyone done this before? Thanks

Z28 Boy

thats how mine is. you shoudl be fine.

-brian

1MEAN92RS

You COULD do it, but why? One way to reduce detonation (esp. on blown applications) is to put a vaccum on the crankcase. So why would you want to evacuate the crankcase any slower?

Nice to see a fellow Virginian BTW

CamaroGuy71

can be done... wont hurt anything.

25THRSS

What exactly is the purpose of the pcv valve? What are the benefits of keeping it or just putting a breather in its place?

25THRSS

Hey Brian, I went onto your site, which by the way is very cool, but the pictures still had the pcv valve hooked up. Did you just recently remove it?

deadtrend1

iTrader: (1)

The PCV valve reduces emissions by allowing gases from the crankcase to be burned by the motor. If you push a breather in where it is, you might get some oil residue on the valve cover near it (dont quote me though).

If the valve wasnt there, then you would loose vacuum in the throttle body. I could go into detail how but if confuse myself along with you.

But in short .... since theres a line running from the crank case to the throttle body, a valve is necessary to hold vacuum. If you use a push in breather and plug the vac. line from the throttle body .... you'll be fine.

CamaroGuy71

there is a baffle inside the valve cover where the breather goes... and yea u might get some oil around there... but you do not want to remove it. it actually helps make ur car run better. brian... in the pic of ur engine... it shows a pcv valve hooked up. i think u were mistaken with the breather on the pass. valve cover. h

Z28 Boy

good call. actually mine is sill hooked up. i must have not read the first post correctly the first time , or just had my head up my ***.

my pcv is still connected...it is the breather on the passenger's side valve cover that was replaced with a puch in type.

sorry...brain fart.

-b

25THRSS

why would it make my car run better?

1MEAN92RS

So is the pull from the PCV not enough to help quell detonation? If PCV is totally an emissions thing, then I will replace it with a much more sightly breather cap ASAP. Up until now I had always been under the impression and told that PCV helped to stiffle detonation.

Later,
Harry

25THRSS

Ive never heard of that. I dont think it effects detonation at all, but I could be wrong. Anyone?

Dan W

PCV for positive crank case vent.

It puts a vacuum on one valve cover and a inlet (that goes to the air cleaner in stock form) on the other. Thus pulling fresh air through your crank case and whatever made it past the rings with it back into the combustion chamber to get burned in the combustion process.

Since there is a vent on one side their is no vacuum created in the crank case. The system does create a rather large vacuum leak but in stock form thats ok because the motor is tuned for the added air at idle... if you were to block it off the IAC would have to open more which is loud and I suppose could cause some idle problems if it can't open enough to adequatly control idle.

I'm not aware of any performance advantage to removing it and it does function to keep combustion products out of the crank case where they can contaminate your oil....
If you had a car with an aftermarket cam that you were trying to get every bit of manifold vacuum out of to gain tuning resolution maybe then you would have a good enough reason to get rid of it.

As far as stiffeling detonaton, there is nothing about the PCV that would cause it to do that. Quite on the contrary, it has the effect of leaning a mixture since it is adding air... not making it rich. Maybe you are thinking EGR which lowers combustion chamber temps by pumping spent thus inert exhaust gasses into the combustion chamber.

JPrevost

PCV is a funny beast. From what I've gathered it only is used when there is vacuum OR crank pressures built up high enough to need the use of both "vents".
Like Dan said, if anything, it'll actuall make for detonation. Oil fumes and oil in general will detonate before a good high octane gas. I don't like how the system puts oil into the intake manifold to help burn up the vapors. I'd rather see it being injected into the air fittings on my header and burning off THERE instead of in the chamber itself.
For a performance vehicle I don't like the stock PCV system, for stock or little to no mods, just leave it. So long as it's working (ball inside rattles is a good sign) then you shouldn't see any difference in the cars operation with or without it hooked up to the TB. It also cuts down on vapor smells. Dual breathers will put out some pretty nasty smells in the warmer/hot weather.

CamaroGuy71

umm.... no.

it is a vent... thats it. How do u relieve all that pressure in ur crankcase? Something has to do it. Removing it will just get all that air into the atmosphere... and its not oil. There is a baffle that prevents the oil from getting into the PCV itself. Someone has to do some research on this but i know it is 100% pointless to remove since it huts our car in absolutely no way. Do not remove it cuz thats just stupid. Any you can't get a racing pcv system or anything... like u were talkin about modifying the stock pcv system... it does one thing in one way and it does the best it can do right now... no need for modifying it at all.

edit: JPrevost is right on

25THRSS

The main reason I wanted to remove it is for appearance purposes. I wasnt really looking for a performance gain, just wanted to know if it would hurt me. Looks like I'll just remove it and put a push in breather in its place and it wont hurt anything. Can anyone tell me what the OD is for the correct push in breather? Thanks for the info guys.

1MEAN92RS

Go to the **** sectioin at your local parts store. Those APC breathers will push right in.

CrispyClutch

Yeah discount auto doesnt carry any breathers but the APC's... Theyre overpriced, but I bit the bullet and bought a black one. Looks kinda nice really.

AJ_92RS

You can replace the breather on the passenger side. That's not a big deal. That's all that hose to the air cleaner does is draw in air.

You do want to keep the PCV valve. Here's something I found that should help.

The process of combustion forms several gases and vapors; many of them quite corrosive. Some of these gases get past the piston rings and into the crankcase. If left in the crankcase, these substances would cause all kinds of bad things (rust, corrosion, and formation of sludge), so they have to be removed. Back in the old days, they used to be dumped out into the atmosphere through a tube. Once we realized what a problem pollution was in the sixties, the PCV (Positive Crankcase Ventilation) system was developed to take the place of the old "dump tube."

The PCV system uses a hose connected between the engine and the intake manifold to draw these gases out of the engine's crankcase and back into the cylinders to burn with the regular fuel. The only problem to solve is how to keep these gases from going *****-nilly into the manifold and upsetting the required air-fuel ratio. The solution to this problem is the PCV valve.

The PCV valve controls the release of crankcase gases and vapors to the intake manifold. The valve is kept closed by spring action when the engine is at rest. When the engine is running normally, the low vacuum it creates allows the valve to open and release crankcase vapors and gases into the intake manifold for burning. If the engine is idling or you are slowing down, the vacuum level rises and pulls the valve plunger into the valve opening. This partially blocks off the opening so that only a small amount of vapors and gases can be drawn into the intake manifold.

One really comforting feature of the PCV valve is its behavior in the event of a backfire. If your car backfires in the manifold, the pressure makes the spring close the valve completely. With the valve closed, there is no chance that the flame can move into the crankcase and cause an explosion.

25THRSS

Thanks for the info, that was very informative. I really appreciate it guys.:hail:

Pablo

iTrader: (1)

Bad Idea

I can give you several reasons

1. It helps remove contamination and moisture from the crank case thereby keeping the oil cleaner, longer
2. Removing it does not improve performance at all
3. It helps reduce valve stem oil leakage (on deceleration the intake port can generate some pretty strong vacuum and pull oil past the guide and onto the back of the valve where it cooks into a nasty crust that kills performance, the valve does some to reduce the pressure differential)
4. It will make your passenger compartment stink (I know this, and the above from first hand experience)
5. There are several different valves available so that you get the one according to the amount of vacuum your engine generates and when you want the valve to open. The only difference is the weight of the poppet in the valve. I have never seen one that was spring loaded, gravity does the job of a spring. The poppets have a number on them if i remember correctly and that is how you know which one you have.
Im not sure if a stock pcv valve is even open at idle on a stock car. Regardless of that, on a modified motor with reduced idle vacuum it probably only opens on deceleration or light load high rpm cruise. Keeping this in mind, the thing is designed not to introduce crankcase pressure when the engine is under any decent load so detonation from it isnt so much of a concern. Even if it is and you really want to avoid any oil entering the engine you can always add a filter/baffle to it.


I dont have a pcv on my car and I regret it. If I see my car again anytime this decade im definately rigging up a pcv at the least and more likely a vacuum pump.

steve8586iroc

25THRSS, get a stainless steel braided hose kit and cover it so it will look like a fuel line. Might be the first one to trick it out.

Steve

1MEAN92RS

Pablo has got to be the COOLEST guy ever. It never fails that when there is a question being debated of any importance he steps right up to the plate with a great well-supported answer! Thanks for the info Pablo!

Later,
Harry

Pablo

iTrader: (1)

Aw schucks you're too kind, besides I **** people off and say stupid stuff all the time maybe youve just been reading the better posts