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Discussion Starter · #1 · (Edited)
I have a set of tall valve covers that clear both my RRocker arms and the EFI intake. The problem is , it does not have a baffle.

I have a nice big new air/oil separator for the crank case side of my PVC system ,

Could one delete the existing TB to valve cover line (BLUE) then tee the valve cover port over into the same PVC system( BLACK) to be also collected by my air/oil separator-catch can ?

Would there be enough vacuum to 'power' both ports , any other reasons not to do this ???

Please see my awesome ms paint art for further clarity

1073720
 

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The diagram is awesome. But I think what you are suggesting will not be a correct pvc system. The vent to the TB is for fresh air to go into the crankcase, then it is pulled out through the pvc air/oil separator side.
 

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Discussion Starter · #3 ·
I would think the valve cover to TB port , is usually under vacuum.

After some more reading,
It seems at normal operation , the TB to Valve Cover line is under vacuum, pulling semi-unmetered air from the CC into the intake.
But at full throttle , sustained RPMs - there may be enough CC pressure to overwhelm the PCV system, The VlvCvr to TB line is supposed to act like vent and the intake a catch can. Spewing into the intake.

I guess my only solution is to put another smaller oil separator in for the vlv cover to TB line... or..... Get a better set of valve covers with a baffle :( .

I see which is cheaper.
 

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I would think the valve cover to TB port , is usually under vacuum.

After some more reading,
It seems at normal operation , the TB to Valve Cover line is under vacuum, pulling semi-unmetered air from the CC into the intake.
But at full throttle , sustained RPMs - there may be enough CC pressure to overwhelm the PCV system, The VlvCvr to TB line is supposed to act like vent and the intake a catch can. Spewing into the intake.

I guess my only solution is to put another smaller oil separator in for the vlv cover to TB line... or..... Get a better set of valve covers with a baffle :( .

I see which is cheaper.
There is more vacuum after the throttle body in pretty much every scenario unless you have a turbo/blower.
Air is almost always flowing from TB to valve cover through crankcase and into inlet (or in your case, catch can and then intake)....assuming majority of driving is part throttle.
At WOT you might see some flow from valve cover to TB due to slight positive CC pressure due to blowby and minimal vacuum inside the intake.

And just to be clear, you have the VC line connected to the port on top of the throttle body, correct?
 

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Plug the PCV port in the back of the intake with a freeze plug. Put a vacuum cap over the throttle body and oil fill connections. Weld in a bung on both valve covers and run lines to a catch can.
 

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As Blown85GT has pointed out, the direction of flow will be from the throttle body into the valve cover. It has to do with pressure differentials, so unless you have some form of forced induction (in which case you would need a different air source), this will be the direction flow. Ford did it this way as all the air entering the engine (for combustion) needs to be metered, and this is a source of filtered, and metered air. Just as the air enters the crankcase through the valve cover, the air leaves through the PCV at the real of the lower intake, then into the upper intake. To add a catch can, leave your air supply alone, and place the can between the PCV and the upper.

1073732


Sorry for the crudeness of the picture, but this should describe what you're after. While it would be nice to still have your baffle, removing it isn't the end of the world. Plenty of people have to remove their baffle, especially when using the original valve covers, so this shouldn't be too much of an issue. That said, if you had a real picture (not to disparage your MS paint drawing) of your application, it would help to give better feedback.

1073733


Either way, I've done it this way with plenty of cars and never had any problem. My brother's 90 has over 100k mile like this without a problem. Neither have any of my Mustangs, although they don't get near as much use.

I hope this helps...
 

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While it would be nice to still have your baffle, removing it isn't the end of the world. Plenty of people have to remove their baffle, especially when using the original valve covers, so this shouldn't be too much of an issue.

View attachment 1073733

Either way, I've done it this way with plenty of cars and never had any problem. My brother's 90 has over 100k mile like this without a problem. Neither have any of my Mustangs, although they don't get near as much use.

I hope this helps...
I just pressed this little guy in. By itself it should baffle a bit, but I also stuck some coarse copper wool down the tube to to catch any oil mist. I also run a catch can off the PCV.
F7CFAFAA-4BD4-4472-9FA2-781730F31FC6.jpeg
3FB31CB1-2346-486F-A91B-AE80959A8BE8.jpeg
 
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