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Anybody have a diagram of a PCV system?
Posted by: Brad54 ()
Date: February 16, 2011 06:08AM

I'm working to replicate a PCV system on the wife's car (Lakewood with a 140).

On a V8, it's easy: the PCV system has one "In" side of the circuit, and one "Out" side. "In" goes either through the breather cap, a valve cover breather or a port in the air cleaner, and "Out" goes through the carb base.

They're separate legs.

From what I can tell, there's no individual "In" and "Out" on the Corvair engine. They both go off the tube on top of the block.

So tell me if I have this correct:
"In" comes in from the air cleaner base to the elbow-bent tube.
"Out" is the small restricted port off the side of that elbow tube and goes to the carb bases.

Is that correct?

-Brad

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Re: Anybody have a diagram of a PCV system?
Posted by: richard1 ()
Date: February 16, 2011 06:14AM

what it does is suck air from the engine.
So you need the valve to run from the engine cover to somewhere in the intake. As air is sucked into the carb(s), it sucks some from the top of engine.

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Re: Anybody have a diagram of a PCV system?
Posted by: Richard ()
Date: February 16, 2011 08:06AM

>>So tell me if I have this correct:
"In" comes in from the air cleaner base to the elbow-bent tube.
"Out" is the small restricted port off the side of that elbow tube and goes to the carb bases.<<

That pretty much nails it. There is one thing that can be added to that. When the vacuum signal is low such as during WOT, the crankcase gases will travel out the "In" tube as you call it, to the air cleaner. The carb will then suck those gases in along with the fresh air coming through the air filter.

It doesn't allow fresh air to be drawn into the crankcase like the V8 system you described, but it does burn up the gases and not let them vent into the atmosphere.

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Re: Anybody have a diagram of a PCV system?
Posted by: Richard ()
Date: February 16, 2011 08:17AM

You wanted a diagram. Corvair has used an orifice and a PCV valve. Both are outlined here, except their orifice system uses a second orifice on the "In" tube. I suspect that system would have to be cleaned on a very strict regular basis.
Similar system used on a later import. - Copy cat.



Edited 1 time(s). Last edit at 02/16/2011 08:20AM by Richard.

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Re: Anybody have a diagram of a PCV system?
Posted by: Marco_a_p ()
Date: February 16, 2011 12:31PM

PCV......

Marco
Sun Valley Ca 91352

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Re: Anybody have a diagram of a PCV system?
Posted by: cnicol ()
Date: February 16, 2011 02:18PM

I'd go with the first pic - the "T" and valve will fit nicely under the Lakewood engine cover. In addition to 61-3 engines with PCV, this system was also used on 64-5 FCs and A/C cars

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Anybody have a diagram of a PCV system?
Posted by: Marco_a_p ()
Date: February 16, 2011 03:11PM

If it's a 140, you should use the stock 140 balance with the 61-63 "T". The balance tube already has the sized orifice so no need for the PCV valve. Just run the the hose that supposed to go to the stock air cleaner into whatever air cleaner you plan to use.

My concern has always been with the blowby gases that are vented into the engine compartment and sucked into the heater system by the cooling fan. Plumbed into the stock air cleaner the gases are trapped and cant get into the engine compartment.

With the open element air cleaners, at idle, the gasses will vent out of the air cleaner and into the engine compartment.

I've had the thought that adding a tube that would bring the vent as close to the carb opening as possible. Maybe even all the way into the air horn so that the gases would get caught up in the down draft.

Marco
Sun Valley Ca 91352

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Re: Anybody have a diagram of a PCV system?
Posted by: Brad54 ()
Date: February 16, 2011 06:55PM

Those diagrams helped A TON.
I had the concept correct, except I had the wrong ports going to the wrong places. I thought the restricted orifice would go to the base of the carbs (balance tube), while the larger port would go to the air cleaner.

Thanks for everyone's help.

Now I need to go see what tubes I have with orifices... One was hacked on the car when I got it and the rubber line was just stuck through the bulk head going to nothing.
I have a second one that came with another motor, so I'll see which should fly.

Thanks again guys, this was a huge help.

-Brad

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Re: Anybody have a diagram of a PCV system?
Posted by: cnicol ()
Date: February 16, 2011 07:12PM

Note: the short PCV tee in the photo above does not have an orifice. The only place you will find an orifice is in the long late-model PCV tubes with the big tube pointing straight up near the middle of the motor. That style would be difficult to work into a Lakewood.

I have never seen a stock 140 vacuum balance tube (or any balance tube for that matter) with an orifice.

The short tube has no orifice so it requires a PCV valve (also in the picture above). If you have one of those short PCV tubes, get a Corvair PCV valve and you're good to go.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Anybody have a diagram of a PCV system?
Posted by: stitch ()
Date: February 16, 2011 07:15PM

Orifice.....Just sounds so,so,... Body-cavity-searchish! When talking about tubes, or hoses, there are 'openings' or 'holes' on both ends. Just a weird little word.*orifice*. Proctology comes to mind. I work at a school and the word "Tardy" is used allot. I've asked around and it seems that the word doesn't really exist Off-Campus. I also thank Marco for the illustrations! (Just my own personal gggg for the evening!) LOM's Orifice....Love it!

"If you can't fix it with a Hammer, you have an Electrical problem."
Stitch...
Schertz, Texas.
(Smallish town/burg 17 mi. NE of San Antonio)

'Ms Penny'
!967.. 4th body
8th off the line

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Re: Anybody have a diagram of a PCV system?
Posted by: Brad54 ()
Date: February 16, 2011 08:35PM

cnicol Wrote:
-------------------------------------------------------
> Note: the short PCV tee in the photo above does
> not have an orifice. The only place you will find
> an orifice is in the long late-model PCV tubes
> with the big tube pointing straight up near the
> middle of the motor. That style would be difficult
> to work into a Lakewood.
>
> I have never seen a stock 140 vacuum balance tube
> (or any balance tube for that matter) with an
> orifice.
>
> The short tube has no orifice so it requires a PCV
> valve (also in the picture above). If you have one
> of those short PCV tubes, get a Corvair PCV valve
> and you're good to go.

Well, I've got two PCV tubes: One came with the car, and one came with the motor I bought. They both have the little port with the orifice.
The one that came with the motor I just installed is the stock tube, with the 90-degree upward bend that will hit the cargo deck in the wagon.
The other one that came on the 140 that was in the wagon when I bought it has been cut down... the 90-degree up-bend is gone.

I don't really understand the engineering behind the system on these engines though... both "sides" of the system are directly connected to the crank case. I don't see how the port going from the base of the carbs to the air cleaner isn't a direct leak. With the restricted orifice, it's a very small leak, but it's still a vacuum leak.

BUT, that's the way it seems to have been done, so I'll replicate it.

-Brad

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Re: Anybody have a diagram of a PCV system?
Posted by: MattNall ()
Date: February 16, 2011 08:52PM

Brad,. it's the way all engine's are done...


Vair's just have the Vent and evac. passage connected.





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Anybody have a diagram of a PCV system?
Posted by: Brad54 ()
Date: February 16, 2011 08:58PM

MattNall Wrote:
-------------------------------------------------------
> Brad,. it's the way all engine's are done...
>
>
> Vair's just have the Vent and evac. passage
> connected.



Yeah, that's the part I don't get. They're connected... so what are they really doing? Why aren't they bypassing the crank case during operation?

On a V-style engine, one valve cover has a port going to the air cleaner, while the other valve cover on the opposite side of the engine goes to the carb base; it draws thru the engine.

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Re: Anybody have a diagram of a PCV system?
Posted by: Pacerace ()
Date: February 16, 2011 09:11PM

The way I understand the stock system, is that it only vents higher pressures in the crankcase cause by blow-by, ect. If there isn't enough pressure in the crankcase the orifice/PCV Valve is pull fresh air in from the air cleaner.

In other words, it just vents positive pressures, and does not create a vacuum in the crankcase that pulls fresh air in.

I could very well be wrong, and if I am, it's all just a learning experience. thumbs up

________________________________________________________

Chandler
Powder Springs, GA.



1965 Corvair Monza 110/4sp Coupe



Edited 1 time(s). Last edit at 02/16/2011 09:12PM by Pacerace.

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Re: Anybody have a diagram of a PCV system?
Posted by: MattNall ()
Date: February 16, 2011 09:15PM

Pace... if blowby is low and engine vacuum high... all is pulled thru the orifice..

If there is more blowby than can be pulled thru..the excess goes to the carbs..





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Anybody have a diagram of a PCV system?
Posted by: Marco_a_p ()
Date: February 17, 2011 12:09AM

There I go again.... What was I thinking!!!
Like Craig corrected me... the orifice is in the upper PCV tube. Doh! Xo

Somewhere I had read about a process to either drill out the the existing orifice or installing an orifice in the balance tube. Something similar to a carb jet. this way it could be removed to clean out any built up carbon and sludge.
So I suppose you could use the early upper PCV tube, with the 140 blance tube, either install the jet/orifice or use a PCV valve.

Marco
Sun Valley Ca 91352

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Re: Anybody have a diagram of a PCV system?
Posted by: richard1 ()
Date: February 17, 2011 04:17AM

I maintained my road draft tube for stock, but If I was to put a pcv on it I'd use the current ones that have valves and don't allow for any air to go backwards, only suck from the engine.

Restoration in Bolivia
Richard's Mini Pickup
Richard's Corvair
Richard's Renault Dauphine

Selection of the Right Motor Oil for the Corvair
Selection of the right transmission oil for the corvair
How to polish and restore stainless and aluminum trim

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Re: Anybody have a diagram of a PCV system?
Posted by: deusalpha ()
Date: September 20, 2011 03:27PM

Any chance you have one of those diagrams for a 64 monza?

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Re: Anybody have a diagram of a PCV system?
Posted by: cnicol ()
Date: September 20, 2011 03:41PM

deusalpha Wrote:
-------------------------------------------------------
> Any chance you have one of those diagrams for a 64
> monza?

Does your Monza have A/C?

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Anybody have a diagram of a PCV system?
Posted by: deusalpha ()
Date: September 20, 2011 04:32PM

No



cnicol Wrote:
-------------------------------------------------------
> deusalpha Wrote:
> --------------------------------------------------
> -----
> > Any chance you have one of those diagrams for a
> 64
> > monza?
>
> Does your Monza have A/C?

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