[cv70chall]

Hi guys,

First off , Happy 2016!

The weather here is enjoyable, and I'm taking full advantage of it.
My question today centers around pressures within the valve covers and if it makes sense to have BOTH a PCV and Breather?

I know a PCV valve reduces some of the pressure, but is the pressure in both sides of the engine tied together or separate?
If it's separate, I would think that a breather on the other side of the engine might help.

Thoughts?

[Pat]

I would recomend you to use the pcv whit breather ! The Engine tends to have a littel leak past the rings witch is normal and those gases is better to burn up thru the intake whit a corekt pcv valve but Watch out becas some pcv have less ristriction so i Always end up whit the 71 model year corekt Mopar pcv valve but also the 72 and up works great but looks more incorekt than the 71 for type a 70 Engine bay ! What im trying to say is that the 70 model Mopar pcv valve have less restriction and then you might end up consuming Engine oil in gas form thru the pcv so use the 71 model becas those are better in that sence.

Hope this helps,

[cv70chall]

I can't find a combo. It's either a PCV valve or a breather.

[cv70chall]

I was considering a PCV on the passenger side and breather on the driver's side.

[Pat]

Witch side you use for pcv do not matter as long as you put the breather on the oposit side ! Dont forget to have a screen under the pcv inside the valve cover that have about 1" on al sides under the pcv so it dont suck up oil drips from the rockers that are Close to the pcv becas it will if you dont see to that !!!!!!!! I Always use the stock style of repro or NOS pcv from ma Mopar but breather you can use what you like as long as it has some kind of filter material inside it so you dont suck Dirt thru the Engine.

[fbernard]

The PCV Valve and breather serve two different purposes.
- At idle (with high crankcase vacuum), the engine sucks crankcase fumes through the PCV valve, and the breather brings outside air into the engine to replace what was sucked by the engine (those fumes were simply vented to oustide air on old cars, before the "Clean Air Act").
- At high RPM, when crankcase (over-)pressure might be created by blow-by, the PCV is useless and the breather prevens pressure build-up by blowing excess air outside.

With a stock or near-stock engine, you need both a PCV and a breather.
This setup actually prevents sludge from forming (from oil contaminated with unburned gas and carbon deposits) so it's not just an environmental benefit.

With a modified engine (poor vacuum at idle), you can get by with just the breather, as the PCV valve won't do anything.
If you have your rings cut out for nitrous use (or just too large ring gaps), you will have excessive blow-byabove 3k RPM and you will need two large breathers connected to a puke tank (or a vacuum pump).

[dave-r]

Best to have the valve on the drivers side and the breather on the passenger side. Otherwise at high rpm you can get oil in the breather.

[Pat]

Best to have the valve on the drivers side and the breather on the passenger side. Otherwise at high rpm you can get oil in the breather.

Woow Dave how can you fill up a valve cover that mutch ! Must be a badly built engine

[dave-r]

Chrysler themselves changed which side they go on about 1969? Which is why your 1970 Challenger came like that.

Somewhere on here is a post from years ago where one of our members had oil coming out the breather on a small block. I asked him to try switching sides. It worked.

[dave-r]

I'm not making this up.

[dave-r]

Here is a '68 small block which is before they started doing it the other way around.

I think this was mainly a small block issue. But if Mopar went to all the bother of running a rubber hose from the right side of a carb to the left rocker cover it must have been for a reason?

But what do I know. I'm just an old guy with a Chevy.

[Pat]

It is more likely that they moved the breather to the passenge side valve cover to easy be abel to rout the emisson system for the cars that needed that ! If the Engine breaths out thru the breather in a pcv system when the engine is up and runing there should be a fault eaiter on the pcv valve or the engine has to mutch cylinder leak or a realy poor vacume. The acual point of the pcv system is to never have any presiure inside the engine and a breather whit filter material inside is whats needed in those systems.

But ho am i to know when i drive a Challenger

[Dale1035]

Thanks for the information. I learn something every time I read the message board.

[dave-r]

It is more likely that they moved the breather to the passenge side valve cover to easy be abel to rout the emisson system for the cars that needed that ! If the Engine breaths out thru the breather in a pcv system when the engine is up and runing there should be a fault eaiter on the pcv valve or the engine has to mutch cylinder leak or a realy poor vacume. The acual point of the pcv system is to never have any presiure inside the engine and a breather whit filter material inside is whats needed in those systems.

But ho am i to know when i drive a Challenger

I remembered now why it was. It wasn't oil coming out of the breather. It was because the crank throws a lot of oil up into that right head. If you have the valve on that side it sucks it up and your engine gets to burn it.

The left side head does not have as much oil splashing about up there. So they moved the valve to that side.

That's what it was.
So yes it does matter which side if you want to burn less oil.

[cv70chall]

OK.
That makes sense.
So, can you give me some details as to the best path to route the hose for the PCV?

[Pat]

It is more likely that they moved the breather to the passenge side valve cover to easy be abel to rout the emisson system for the cars that needed that ! If the Engine breaths out thru the breather in a pcv system when the engine is up and runing there should be a fault eaiter on the pcv valve or the engine has to mutch cylinder leak or a realy poor vacume. The acual point of the pcv system is to never have any presiure inside the engine and a breather whit filter material inside is whats needed in those systems.

But ho am i to know when i drive a Challenger

I remembered now why it was. It wasn't oil coming out of the breather. It was because the crank throws a lot of oil up into that right head. If you have the valve on that side it sucks it up and your engine gets to burn it.

The left side head does not have as much oil splashing about up there. So they moved the valve to that side.

That's what it was.
So yes it does matter which side if you want to burn less oil.

The crank can not in any way throw up oil in the heads Dave but shore it can breath out hot oil gas the easyest way witch sould be thru the breather if you have a lot of leak past the pistons and i would bet that the case you are refering to most probably dident have the steel screen under the pcv valve and then the drips from the oil blead from the rockers closest to the pcv valve realy is the reasone for the large oil consuption and as i stated before there are difference in how mutch restritcion there are in witch year of valve you use witch also will do a difference in how mutch oil you will lose in gases and i use the 71 ore 72 and up models when i build engines.

So no it do not matter witch side if you whant to burn less of oil but a steel screen that cover about an 1" inside the valve cover under the pcv valve will matter and witch type of valve you use !

[dave-r]

It's the reason Chrysler changed it Pat but you are right about emissions because the exhaust was slightly cleaner this way around and they figured the right side valve cover was a dirtier atmosphere.

It may not be down so much to actual liquid oil. It might have just been more oil fumes or a higher pressure of fumes in that head due to the crank rotation. Like a cylindrical fan blade blowing all the fumes to that side. It actually makes sense when you think of it that way.

[cv70chall]

So,

Final Verdict..
Place the breather on the passenger side
Place the PCV on the driver's side...AND install a 1" piece of screen directly below the PCV intake.

Yes?

[Pat]

So,

Final Verdict..
Place the breather on the passenger side
Place the PCV on the driver's side...AND install a 1" piece of screen directly below the PCV intake.

Yes?

For more practikal resone yes plase the breather on the rear of the passenger side valve cover and
the pcv on the driverside rear valve cover whit a 1" screen below the valve inlet inside the cover
1/4" space in betwen so it can breath but not suck in oil drips from rocker arms splashingaround inside.

I try to base my statement whit facts becas speculation will only confuse and end whitout good result
so if i dont know i try to find out the hard way but as a good friend of mine that is a wizard on race enging
once said to me (When the wise man points out the moon the fool looks at the finger).

[cv70chall]

My breather is only a breather and has no hose outlet.

[dave-r]

For more practikal resone yes plase the breather on the rear of the passenger side valve cover and
the pcv on the driverside rear valve cover.

Which is exactly what I suggested....

[cv70chall]

Thank you, oh wise one...

[fbernard]

oh wise one...

Don't push it too far, he bought a Chevrolet, after all...

[dave-r]

Push all you want while you can because from the 1st March this board is history.

[fbernard]

Push all you want while you can because from the 1st March this board is history.

Yes, just saw that this morning, and your new signature.
Where will I get my daily fix of news from non-frog-eating Mopar addicts after March 1st?

[dave-r]

It's had it's day mate.
It's not heavily used and these are a lot of resources out there these days that are a lot more busy than this old place.
Everything comes to an end eventually.

[Pat]

For more practikal resone yes plase the breather on the rear of the passenger side valve cover and
the pcv on the driverside rear valve cover.

Which is exactly what I suggested....

Any engine builder would back up that you can put the pcv valve on witch valve cover you would prefere becas it would have same result if it is placed so that there is a screen under it and any nonsent regarding more tubulence on what ever side is not in any way true becas the heads will leak up or bind the same amount of oil/fume very easy proven but al component must work corekt or you will have oil driping out of the breather isted of filterd air going in the engine in smal amount. I hate to compeat of badtalk anyone will al due respekt and will not coment this subjekt any more becas it´s plain stupid to argue

[dave-r]

Alright Pat. Don't have a stroke.

It was something that came up once years ago. So long ago I don't remember correctly. But Chrysler changed it for a reason. It was much easier the other way around. But they changed it anyway for the 1969 model year and I seem to remember reading about it back in the 90s. If it didn't matter what side they used why change it?

I read about it somewhere. When I say I didn't make it up I mean it was in a tech manual or something. I just don't remember where.

[Pat]

Alright Pat. Don't have a stroke.

It was something that came up once years ago. So long ago I don't remember correctly. But Chrysler changed it for a reason. It was much easier the other way around. But they changed it anyway for the 1969 model year and I seem to remember reading about it back in the 90s. If it didn't matter what side they used why change it?

I read about it somewhere. When I say I didn't make it up I mean it was in a tech manual or something. I just don't remember where.

Dave it´s cool and no stroke at my end !

The resone for the change whas as i told you before that they dident whant to route the emission tubes on the driver side of the car and thats pure lodgic as the tubes should be runing whit the fuel lines. Regarding the case you are refering to were it helpt to change side for the pcv i gues you dont know half of the sircumstances becas did the guy have the screen from the begining and did he or here use the same parts like pcv&breather and i gues you dont. What im trying to tell you is that some cases when you read or here a story it can acualy be a myth like when everybody whas told that the Earth whas flat and i hope you dont go around beleving that !? As far as i know there are alot of pre 70 cars restored out there in original spirit that is proof of that they dont burn up more oil fumes then 70 and up.

The guy that askt the original qestion might end up beleving the myth when you think of it and i gues that that could be a bad thing !?