I'm putting my chrome valve covers on friday hopefully, and I'm wondering about breathers. What's the story on 'em? If you have PCV, you shouldn't put on a breather? Or if you have PCV you do NOT put on a breather? Would it effect my engine at all if I put one of those open filter non PCV breathers on it? Would I get some kind of caution/warning light? I think it pretty well defeats the purpose of PCV, but I just think they look plain cool Also, what keeps the oil from splashing back through the filter? Or is it not shot out hard enough to come through the breather?

 

Forget the breather idea and keep the PCV vavle stock. It may not look COOL but they work.

 

I have a breather on the passenger side and the PCV on the driver side.

 

i use a breather on one side and PCV on the other. Dont hook the PCV valve to a vacuum source if you have a breather or you will run like ****. you have to run it into the air filter or someplace upstream of the carb/t.b./ etc. i dont like the idea of a lot of vacuum in my crankcase anyways, since i have seen valve cover gaskets sucked in at high rpms.

 

"since i have seen valve cover gaskets sucked in at high rpms"

Ughhh WHAT ? There is NO vaccum at high RPMs. Just a lot of blow-by. How would that suck the valve cover gaskets ? You must have been dreaming when this happened. Even at idle when you have the most vaccum it barely sucks your finger (lol), let alone a gasket sandwiched between the head and the valve cover using four bolts that I'm sure are pretty tight on there. I dont know.. it just doesnt make any sense to me!

 

Here's a question, when I had my breather put on, my Dad said to block it off, so he put a piece of plastic over it, and my brother said leave it off, that's the purpose of the breather, what do you guys think?

 

"You must have been dreaming when this happened."

LOL...Really.


:hail:IROC-Z

 

I hate to flame but bottle power needs to put more n20 to his car and less to himself. Vacume on the crankcase is good. Some high end racers even run vacume pumps to put a vacume on the bottom end to reduce blow by, I read in one case a 900 hp motor gained 40 hp from it. i run a pvc valve and block the breather hole.

 

Would I notice any improvement in how the car pulls by blocking it, it's been so long since it's been blocked.

 

I'd like to know as well. Sort of for my Formula, but mostly because of the Cobra.

 

I would try it, but the car is at home while at college so I'll have to wait till the weekend. I know some people might say why don't you go out and find out...

 

I know it had a positive effect on reducing blowbye in my old 305. It would burn bout a quart of oil a tank. I capped off the breather hole because i had an open element air cleaner on it so the pcv was sucking a vacume on the crankcase. If i were to unhook the pcv it would smoke so much that people couldn't follow me down the street. So the added vacume was keeping the oil where it was supposed to be. I believe the added power on the higher HP motors is because the crankcase vacume helped to remove traped gasses between the rings and make a better ring seal, therefore making more power. Just my .02 cents from what i have read over the years.

 

I would not run a car without PCV - it removes all the bloby gases from the crankcase and it causes the rings to be sucked up aganst the cylinder walls (yes even with the little vacume that there is) wich reduces blowby and helps with power. also it removes steam and other contamanits from the crankcase wich will F$%k up your oil in no time flat.

 

Well, I'm running a PCV, but on the other side is an open breather.

 

Mark
Why???????use that one breather???

 

You got me, my brother put them the one of for me and I need a PCV right, cause when it's unhooked the car runs like crap..

My brother said the one breather will help out HP, not much at all but it would help..
Then I have my Dad telling me to cap it off.

 

It kinda just hit me but think what pcv means Positive Crankcase Ventilation. It's purpose is to put a vacume on the crankcase. The breather is just like a big vacume leak so cap it off and you'll get more vacume.

Take a look in summit they make a kit that installs in your exhaust and then hooks up to your valve covers to suck a vacume on your crankcase. Whip out a car mag and look at how many of the race cars have this installed.

 

BMmonte,

No flame, but I would take advice on the subject much more readily from someone who knew how to spell vacuum. I'm not the spelling expert or anything, I mis-spell my own share of words, but if I am going to take advice on a subject, it certain looks better if the person giving the advice can spell the word properly.

It is very true that with out some sort of vent the gases will destroy your engine by corroding the metals. Ever notice that even dragsters run some sort of vent? They are rebuilt constantly. This should give you some sort of an idea how quickly those gasses build up and how quickly they can destroy your engine!

Maybe if someone could explain exactly how the PCV works it would shed some light on the situation. I was under the impression, (but I've never really checked on it) that when the engine is at high speeds and the vacuum drops that the valve actually closes.....but I may be way off base here.

I'm just curious how blocking off the vent side when running a pcv could produce more power. B/c if it's true, I'm all over it. However, I don't want to do it at the expense of engine life.

 

No flame taken I can't spell even if I have a spellchecker.

I think the idea of the pcv system was to draw fresh air into the crankcase through the vent which was in the factory air cleaner and then suck out all the contaminants in the crankcase through the pcv valve. I'm pretty sure this was done for emissions reasons, don't want any nasty oil mist or blowby destroying our ozone. The pcv valve is nothing more than a one way valve. In theory you wouldn't need it because all your doing is creating a blow through situation in the crankcase, but you have to remember that the pistons are moving up and down so the internal volume of the crankcase is constantly changing. I believe that is why having vacume in the crankcase will free up power it will help to keep a vacume and not a high pressure situation. Kinda even out the internal pressure if you will. That's why there is a one way valve in the system, to keep from adding pressure to a vacume source on the carb. This is just my theory on the subject I'm no expert but I have spent some time trying to understand the whole idea of having the pcv system.

 

Boy oh boy, where's Vader at???

 

So which activates the valve, crankcase pressure or the vacuum from the carb, or both?

The only way that it makes sense to me that the pcv could produce more power is if it wasn't run through the carb b/c the carb would be burning the gases, instead of air/fuel mixture.....

As far as pressure goes inside of the engine, I don't know how this would create or decrease power.....I don't understand.

 

From what i understand when setup the way the factory has it , it won't increase power at all. It will just burn the airborn contaminants in the crankcase. But if you block off the breather hole you will get a vacuum and help to keep the rings seated. How much power this is worth is anyones guess, but if the racers use it i'll use it. As for the valve, it only alows vacuum from the carb.

 

That's not correct, you're confusing WOT with high RPM. Vacuum is maximum when the throttle is closed at high RPM.

Put a breather in one valve cover, and a PCV valve in the other. The PCV system draws clean air in through the breather to replace the blow by gasses, which are sucked into the intake and re-burned. Earlier cars without PCV used a road draft tube to draw the gasses out. If these gasses aren't removed, over time they will form acids in the oil which will reduce the life of the engine.

Some drag cars use a vacuum pump to keep the crankcase under constant high vacuum to make the rings seal better and produce more horsepower, although they'd probably get more power by getting the rings to seal correctly on their own and not using the pump.

 

you need a breather for the system to work right if there's no breather, you'll just suck some gasses from under the valve cover but once the vacume reaches the same point at wich the engin is pulling it will stop sucking gasses through and you will have the same problem as you orrganally started with- stagnent blow-by gasses in the crankcase. the filter element in the breather will have enough resistance to keep the vacume signal good. also the pcv valve is just a check valve that keeps things from getting sucked back into the engine when you have a low vacume condition (such as WOT) and the a piston is on the up stroke causing a vacume in the crankcase.

 

This is the type of setup I run. An open breather on the right side, and the stock PCV valve setup on the left side. My car doesn't use oil excessively and it does not smoke at all.

And if you look at the factory setup, it uses a breather of sorts to get fresh air into the engine, but it uses a tube that pulls air from the intake stream that comes through passeges in the throttle body.

 

I run a PCV valve on one side and a PCV filter on the other.

 

Apeiron is right. It's Positive Crankcase Ventilation. The PCV valve lets some vacuum from the engine to suck on the valve cover. A PCV filter/breather allows air into the engine crankcase and the crankcase is then ventilated. In one side and out the otherside. It works the same if you have a PCV filter in the air cleaner or just a chrome breather on the valve cover.

 

Any problems with that setup? Also how long have you used it? I want to do the same thing just to reduce the number of hoses I have to look at and work around.

 

Save yourself some hell and get the Breather that has a PCV port on it. For 12 bucks try it and if it runs like krap take it back.


>ever hear of a pcv oil canister?
>btw I'm a Terrible speller no shame here.

 

Here is a pic.

 

That's the kind I have on the passenger side.

 

Really, I'm looking for a different pic cause that came from a mopar site. Good example though.

 

Are you saying to use that kind of breather instead of the open element kind that matt is using, or are you saying to use that kind of breather on the PCV side? In the first case, why? In the second, why would I not just use the stock PCV stuff?

 

Like I said at the begining of these Posts, leave it STOCK! No Pain and No actual Gain. My opinion again.

 

Well three reasons that I can think of.


>pass emissions (those new laws will be rough)
>the vacuum can extract vapor instead of it freely flowing out
>possibly that breather can act as a fiter and trap oily vapors instead of those going back into the engine

 

So what is the consensus? A breath on one side with PCV on the other? Stock? I'm still confused....

 

I've had it that way with this engine the entire time it has been running and it works perfectly.

I had the same setup on my last car as well (85 TPI 305 T/A) and it also worked perfectly. I even swapped back to the stock setup to see if I noticed a difference on that car and it ran the same with either setup.

That right side valve cover on the stock system lets air into the crankcase from the intake air stream so putting an open element breather in there doesn't change anything aside from where the air comes from. Won't change a thing as far as the PCV system is concerned. If you look at the passages in the throttle body you can see where the air comes from the intake ducting and through the TB and out to the valve cover.... I imagine that the factory did it that way to ensure nice clean and dry air goes into the crankcase, but I only drive my car in the summer and not in the rain so there is no chance of dirt getting in there for me.

I have heard arguments that MAF cars will have a slightly higher amount of air coming into the engine than the MAF is normally calibrated to deliver to the engine since that amount of air is no longer going into the crankcase after it passes through the MAF and is now going into the engine. But I suspect that the small change is nowhere near enough to cause problems. I haven't noticed a problem with it in all of my PROM burning endeavors on my GTA either.....

So slam a cool lookin open element breather on the passenger side and call it a day .

 

It's basically the same thing. You'll be fine either way. Just be sure you keep the PCV system in operation.

:hail:IROC-Z

 

Keep it stock. Even an 'open' breather will throw off the air fuel ratio in MAF cars because the fresh air from the intake side is taken after the MAF sensor. Putting an open element is like creating a vacuum leak.

For MAP and carbed cars it probably matters less. I wouldn't plug it though. If you are getting alot of blowby and plug it up, there's a chance of dropping power, excessive oil consumtion from the pressure pushing the oil into the combustion chamber, and massive oil leaks as it forces oil through any opening (possibly creating new ones! )

BTW the Mopar breather pictured above is not a PCV valve breather combo. It has no check ball and would be a MASSIVE vacuum leak if hooked to an intake vacuum source

 

Sorry to sound dumb, but I have a similar one as above but made by Mr. Gasket. So I should plug it then?

 

Hey mark does that breather you have, does it have any vents on the bottom?

 

Hmm.. Well I agree that you will be slightly altering the amount of air that the engine ends up getting versus what it thinks it is getting for each g/sec of MAF, but it in no way comes anywhere near what a vacuum leak will do. The change is negligible at best and pretty much will not effect the way the car runs - especially with the stock bin being so rich in the first place. And since tuning your own PROM is so much fun and beneficial, if you are that concerned about skewing the 'air fuel ratio', you can just get yourself set up to tune your own PROMS and get in there and tweak a few things here and there and it will back to the stock pig rich programming in no time if you so desire.

 

I'm with Hg--I'm still not sure on what the consensus is. I am leaving the PCV valve and connections alone--the whole driver's side part will stay stock on my car. I don't want to speak for the rest of you, but it sounds like we're all keeping our PCV valve and connections stock. On a MAP car (or a carbed car) is it okay to replace the TB to valve covers air line with a breather? What about the part where Matt says that the TB provides dry air? Does that matter, i.e., what if you're driving while it's raining so that the air is very damp?

 

The PCV system draws air in from a source, commonly a vented oil filler cap, (IIRC on the TPI that little hose coming off the TB may be ours, not sure, it's been a loong while) and allows this air to mix with the noxious fumes generated by blowby and the breakdown of the oil also. This mixture then exits the crankcase through a metering valve (PCV) and is drawn into the intake flow, where it enters the combustion chamber to be burned. As a side note, the PCV valve <i>is</i> a metering device and when the pressure gets to a certain point (i.e., high RPMs) will open from the pressure created in the crankcase, of its own accord. As for the vacuum to increase the seal of the rings, this is true. However, there is a slight draw on the cylinder rings at low RPMs with the PCV and none as your RPMs climb, that is why the racers either use a pump or an attachment to the exhaust system. Did I cover most of it?

 

I'm not sure if it has vents on the bottom, I'll get a pic tomorrow of it.

 

damn red devil is allot better explaining things than I am, that's exactally what I was trying to say.

 

Well, lets think about this more logically. I was just speculating on why the factory felt it necessary to pull the air through the intake ducting and the air filter instead of having a regular breather or an open element one on the car.... I was thinking that it is to ensure that clean and dry air goes into the engine through the PCV system. But a breather will do the same thing, since it has a filter element in it. So, while the clean and dry air is a good thing, that really can't be the main motivation for the factory to use this system.

Now, bear with me here folks, I'm no Vader. But the more I think about it, the more I see the main reason for the factory doing the 'sealed' PCV system is for emissions. Because like Red Devil said, the crankcase develops more and more pressure as the rpms increase since the pistons are pumping up and down so fast in a confined area, and an open breather will let air out of the crankcase at that point and those gasses would go straight into the atmosphere. So by having that breather tube go into the intake stream of the engine, those gasses go into the engine through that route or through the PCV valve and not into the atmosphere when the pressure builds in the crankcase. The blow-by goes into the engine and is burned and then cleaned up by the catalytic converter and comes out of the tailpipe as daisies and roses and keeps the tree-huggers happy.

As for water, I can see how an open element breather may get some water to go through it if water somehow got directly shot into it, but I seriously doubt that it is anything to worry about unless you get the car under water up to the breather and that will be the last thing you need to worry about at that point.

So I don't blame you MAF guys for being a little leary since it is garunteed to skew the MAF calibration (not enough to worry about for most people, IMHO though....). But the carbed and SD guys have no reason not to get an open breather on their cars. If for nothing else, to keep the inside of the plenum, runners, and manifold cleaner. But a nice breather will look much nicer than the factory pipe setup, and will allow the removal of a decent amount of BS from under the hood, making it look nicer and make it slightly easier to work on. I am doubtful of any gain in power, but it may let the crankcase breath better at high rpms.....

Well, that's my $.02 on it for now (more like about $.06 now...lol)....
Laterzzzz,
Matt

 

A lot of what has been said seems to make sense. I wonder if Vader does have anything to say...

 

i dont really know too much about it,but my dads nova just uses 2 breathers, no pcv valve.His car is carbed,if that makes a difference.

 

Using just breathers with no PCV is like never flushing your toilet.