PCV/CCV and breathing cap

[norwegianvette]

Hi again

Is the valve on the passenger side valve cover the PCV valve and will the PCV and the CCV be the same? I installed new chrome covers and to seal the hole on the driver side i installed a breather, will this be ok or will it mess up the operation of the PCV?

Thanks for your patiens guys.

 

[boomdriver]

Having the "extra" hole in the other cover without being closed does not help the PCV system. Its like an air leak.

PCV is engine vac sucking raw fumes from the crankcase. The crankcase should be sealed, so this should keep a certain amount of vacume unless your engine has serious blow-by issues. Leaving a way for air to get sucked into the crankcase thru a breather probably lowers the vacume and prevents the PCV system from pulling all the CC fumes efficiently.
You may have to find the right size grommet, fit another PCvalve in there and add a line from the new fitting to a "T" in the old PCV line so the system has the vac in the CC that it was designed to have. Or, plug it somehow. Without seeing it, I could not say how to do that.

I had a similar issue with some chrome covers...had to find a grommet that fit in a breather that had a vac fitting on the cap...then run that to the stock PCV line. Later found the right grommet to fit the covers and hold a PCV directly and threw away the chrome breather cap.

 

[norwegianvette]

Thanks. I tought so, i will seal the breather i think. That way it want draw air and can still be there, that thing looks quite good Must be some liquid metal i can use to fill the tube with.

 

[norwegianvette]

No i am very confused:confused. I did some googel and came to a page regarding PCV/CCV and they recommend a breather on the opposit side to draw some air through the engine. Originally there was no breather and no holes in the driver side cover so there must be a reason GM did it this way. :W

 

[vetteoz]

Originally there was no breather and no holes in the driver side cover so there must be a reason GM did it this way. :W

Because LT1 ( and L98 ) gets PCV supply air from the port on TB (Breather ) to the pass side cover

On LT1 air comes out to PCV valve from under intake so no hole in drv side cover unlike
L98 which has hose from drv side cover to PCV valve

 

[vetteoz]

The crankcase should be sealed, . Leaving a way for air to get sucked into the crankcase thru a breather probably lowers the vacume and prevents the PCV system from pulling all the CC fumes efficiently.

As noted above ,
PCV systems are not sealed from the factory ; fresh air is constantly drawn through the crankcase to purge fumes.The factory system does not try to maintain a vac; the vac is only a means of moving the air through engine.
That is why it is called;
Positive Crankcase Ventilation
not negative ( vac ) ventilation

Only problem with running open breather on rocker cover is on MAF cars because air flow is not metered so is basically a vac leak.
On MAP cars ECM will compensate

 

[boomdriver]

As noted above ,
PCV systems are not sealed from the factory ; fresh air is constantly drawn through the crankcase to purge fumes.The factory system does not try to maintain a vac; the vac is only a means of moving the air through engine.
That is why it is called;
Positive Crankcase Ventilation
not negative ( vac ) ventilation

Only problem with running open breather on rocker cover is on MAF cars because air flow is not metered so is basically a vac leak.
On MAP cars ECM will compensate

Ok,
so 'sealed' is the incorrect word,. but its not far off...

http://www.filtercouncil.org/techdata/tsbs/94-2R1.pdf

In a properly operating closed PCV system,like in C-4 and later Vettes,and most engines since the late 60's, even pulling the dipstick when the engine is running creates a vac leak, and will effect the way its idling. You are correct, "sealed" is not the correct descriptive term. It's "closed". Even though the Name is Positive-Crankcase Ventilation, there is always negetive pressure under the piston in these 'closed' small block Chevys. The meaning of "positive" in this case is that the ventilation has help thru intake vacume.

Fumes are scaveneged thru the TB port (instead of a carb) where intake vac is fairly high. There is no air flow thru the CC unless there is a serious valve seal or ring issue. A demonstration is pulling the PCV as it idles and taking note of what the idle does...Then cover the suction hole in the valve (note the large vac) and notice the engine returning to normal. The L-98 has a vent to the TB on one side and the other is directly to the intake manifold. The LT goes to the intake as the photo indicates.

 

[boomdriver]

Thanks. I tought so, i will seal the breather i think. That way it want draw air and can still be there, that thing looks quite good Must be some liquid metal i can use to fill the tube with.

There are breather caps (aftermarket chrome )that have the vent thru a tube on the side that can be capped with a rubber cap to seal the breather. I would'nt try to plug the hole with anything that might break apart or go inside the engine. Use something made to fit that grommet in the valve cover. Silicone or other sealers might get sucked in.

 

[vetteoz]

Fumes are scaveneged thru the TB port where intake vac is fairly high. The L-98 has a vent to the TB on one side and the other is directly to the intake manifold.

Opposite
Under hi vac situations ( idle / cruise ) air is drawn in from TB supply port through engine to PCV valve on intake .
Under low vac (WOT ) crankcase pressure pushes engine fumes back up the supply line to the airstream in front of TB which accounts for why some complain about oil in their TB when driving hard

Disconnect the line to pass side rocker cover at TB and see which side has vac on it @ idle
Guarantee you won't have any on the TB port side because it is from a hole in front of butterflies ;
NO vac except draft from passing airflow

FWIW
Most hot rod / modified carb engines are running a PCV have a breather on one cover with no problems.
All they have done is replace the air tube that used to run to the air cleaner in the stock factory setup

 

[norwegianvette]

Because LT1 ( and L98 ) gets PCV supply air from the port on TB (Breather ) to the pass side cover

On LT1 air comes out to PCV valve from under intake so no hole in drv side cover unlike
L98 which has hose from drv side cover to PCV valve

Thanks.

I will put a oil filling cap where the breather are to seal that hole. That way i will have one each side

From the picture the PCV are on the intake, what is the name of that valve i have on my passenger side valve cover (looks like a PCV to me)?

Sorry for being a pain, just confused and want to make things the right way and give my engine a good life

Steve

 

[toptechx6]

Thanks.

I will put a oil filling cap where the breather are to seal that hole. That way i will have one each side

From the picture the PCV are on the intake, what is the name of that valve i have on my passenger side valve cover (looks like a PCV to me)?

Sorry for being a pain, just confused and want to make things the right way and give my engine a good life

Steve

There is no "valve" in the passenger side cover, the hose you see from the throttle body to the valve cover is the fresh air supply to the crankcase mentioned by vetteoz.

 

[vetteoz]

There is no "valve" in the passenger side cover,.

Is only a plastic fitting to install hose into the grommet in the rocker cover