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PCV is confusing lol

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Old Feb 19, 2026 | 07:40 PM
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Default PCV is confusing lol

I am running Holley tall valve covers. They do NOT have a PCV. They have baffles and each cover has one vent tube. My valley cover does not have a vent.

can I just run both valve covers to a breather tank?

motor is iron 6.2 with .630 cam 225 heads fast 92 42lbs injectors



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Old Feb 20, 2026 | 02:37 AM
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Boosted 6.0, cammed. I just run 10 AN from each to a catch can, seems to work just fine. I don’t have fancy valve covers like you tho, just modified stockies
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Old Feb 20, 2026 | 09:54 PM
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Originally Posted by Graham Dwernychuk
Boosted 6.0, cammed. I just run 10 AN from each to a catch can, seems to work just fine. I don’t have fancy valve covers like you tho, just modified stockies
Two lines to one can?
Breather can or just sealed ? Any vacuum on the can ?

I was thinking of using a T for both valve covers , then to intake for vacuum…

there’s just so much different info out there , and guys with the older hollies seem to be sucking oil into the can rapidly
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Old Feb 21, 2026 | 02:44 AM
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Help me understand PCV ?

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Old Feb 21, 2026 | 02:56 AM
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I have those on the 427 and I just removed the hose fittings and drilled and tapped the valve covers for 3/8 NPT and installed 10AN bungs on them. I then ran two 10AN lines to a single breather can and capped off the intake manifold and throttle body ports. This is an option if you want to ventilate the crankcase and not allow the intake manifold to pull air through the engine and send the crankase vapors into the manifold. If you wish to run PCV you can leave the valve covers as-is, connect the driver side port to a sealed catch can. From the catch can run a hose to the intake port but install a PCV valve in between the can and the intake manifold port. For the passenger valve cover you can connect a hose from that cover to the throttle body. That is if it has a port for a hose and if it dosen't then you could install a hose barb into the intake elbow or the air intake tube going to the throttle body.

Those are two different ways to ventilate the crankcase. One uses a breather can or cans which has an air filter on it and is merely a system designed to relieve the pressure in the crankcase by emitting the crankcase vapors into the atmosphere and the other is a can without an air filter also known as a sealed catch can which is used for PCV systems where the crankcase vapors are sucked back into the engine by the intake manifold so it can mix with the fresh air coming in from the throttle body to be reburnt. A cleaner way to deal with the crankcase emissions but it does lead to deposit buildup inside the engine over a period of time. In that video he's incorrect. That PCV valve looks to be threaded and has an o-ring meaning the sealed can can accept that PCV valve and the nipple is where you would connect the hose to the intake manifold port not the valve cover.

Mighty Mouse Solutions has many different types of setups depending on what your looking to do so there's that option as well.

Hope this helps ..

Last edited by 01CamaroSSTx; Feb 21, 2026 at 03:06 AM.
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Old Feb 21, 2026 | 03:07 AM
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Help me understand PCV ?

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Old Feb 21, 2026 | 10:17 AM
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Originally Posted by 01CamaroSSTx
I have those on the 427 and I just removed the hose fittings and drilled and tapped the valve covers for 3/8 NPT and installed 10AN bungs on them. I then ran two 10AN lines to a single breather can and capped off the intake manifold and throttle body ports. This is an option if you want to ventilate the crankcase and not allow the intake manifold to pull air through the engine and send the crankase vapors into the manifold. If you wish to run PCV you can leave the valve covers as-is, connect the driver side port to a sealed catch can. From the catch can run a hose to the intake port but install a PCV valve in between the can and the intake manifold port. For the passenger valve cover you can connect a hose from that cover to the throttle body. That is if it has a port for a hose and if it dosen't then you could install a hose barb into the intake elbow or the air intake tube going to the throttle body.

Those are two different ways to ventilate the crankcase. One uses a breather can or cans which has an air filter on it and is merely a system designed to relieve the pressure in the crankcase by emitting the crankcase vapors into the atmosphere and the other is a can without an air filter also known as a sealed catch can which is used for PCV systems where the crankcase vapors are sucked back into the engine by the intake manifold so it can mix with the fresh air coming in from the throttle body to be reburnt. A cleaner way to deal with the crankcase emissions but it does lead to deposit buildup inside the engine over a period of time. In that video he's incorrect. That PCV valve looks to be threaded and has an o-ring meaning the sealed can can accept that PCV valve and the nipple is where you would connect the hose to the intake manifold port not the valve cover.

Mighty Mouse Solutions has many different types of setups depending on what your looking to do so there's that option as well.

Hope this helps ..
basically setup like this correct ?
no check valves ect just vent the pressure





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Old Feb 21, 2026 | 10:30 AM
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Smokie- PCV stands for Positive Crankcase Ventilation, which is NOT what you show above. You show a Passive Crankcase Ventilation setup, which is half-*** at best.
For proper PCV, you first pull fresh air from the air intake AFTER the MAF (if used). Route that line to an unrestricted valve cover hose nipple. That clean air will then go thru the engine picking up all kinds of nasties as intended, making its way to the opposite valve cover with either a restricted nipple or PCV valve. From there to either a catch can and then a manifold vacuum source OR straight from valve cover to manifold vacuum source. DONE.
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Old Feb 21, 2026 | 11:04 AM
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Originally Posted by Sm0kie
basically setup like this correct ?
no check valves ect just vent the pressure



You still need to evacuate the catch can and send that back into the intake manifold.
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Old Feb 21, 2026 | 12:40 PM
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Originally Posted by Sm0kie
basically setup like this correct ?
no check valves ect just vent the pressure



That is correct!
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Old Feb 21, 2026 | 12:51 PM
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Notice the 10AN on the passenger and the other 10AN line on the drivers side valve covers? Those both connect to the Moroso breather can shown in the image. As for the intake manifold and throttle body they are capped off.
Notice the 10AN on the passenger and the other 10AN line on the drivers side valve covers? Those both connect to the Moroso breather can shown in the image. As for the intake manifold and throttle body they are capped off.

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Old Feb 21, 2026 | 03:21 PM
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Doesn't a PCV can like a Mighty Mouse pull vapors out of the engine and then feed the clean air back into the manifold?
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Old Feb 21, 2026 | 04:59 PM
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Yes, it does.
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Old Feb 21, 2026 | 08:48 PM
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Originally Posted by 01CamaroSSTx
Notice the 10AN on the passenger and the other 10AN line on the drivers side valve covers? Those both connect to the Moroso breather can shown in the image. As for the intake manifold and throttle body they are capped off.
Notice the 10AN on the passenger and the other 10AN line on the drivers side valve covers? Those both connect to the Moroso breather can shown in the image. As for the intake manifold and throttle body they are capped off.
thanks man! I appreciate actual experience w/ photos.

question about that can. Does it have internal baffling ?
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Old Feb 21, 2026 | 08:52 PM
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Originally Posted by wannafbody
You still need to evacuate the catch can and send that back into the intake manifold.
I do my own research too and found that according to motion race works that is not necessary. It’s just to prevent the smell , which I believe will mostly be at high load. One could take the breather filter off and route it to the intake.
some say we need to pull the vapors out with vacuum, other say it pulls the oil out. With a good baffling system that won’t happen. I do think I’ll run two check valves that allow air out but none in.

here’s the proof from motion who knows better than most of us Here I’d argue

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Old Feb 22, 2026 | 12:16 PM
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I run a Mighty Mouse catch can with PCV and it's been great for my setup. 2 -10AN lines from the fronts of the valve covers into a Y and into the can, and a line out of the can to the intake. It does not consume oil, in fact the catch can rarely has any oil in it when I drain it.
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Old Feb 22, 2026 | 07:17 PM
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Originally Posted by Sm0kie
thanks man! I appreciate actual experience w/ photos.

question about that can. Does it have internal baffling ?
It has a wire mesh inside the can. I've never seen the can fill up with oil per say but it does fill up with condensation during the cold months and since there's some traces of oil that does collect in the can it looks like a light brown milky substance and you will notice water coming out of the can when you drain. This is only if you run the car in the cold because I never see anything coming out of the can during the summer months.
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Old Feb 22, 2026 | 07:57 PM
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I think another great way of dealing with these blowby gases would be to vent each valve cover down to the exhaust pipe on each end of the header collectors or after the catalysts if you're running cats. I have no problem with this as a way to get the blowby gases out and frankly that would be a much cleaner way than to use the intake manifold to suck that crap back in through the induction system, back into the intake runners and into the combustion chambers and through the exhaust. My opinion and you know what they say about those.
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Old Feb 23, 2026 | 02:40 PM
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Originally Posted by 01CamaroSSTx
I think another great way of dealing with these blowby gases would be to vent each valve cover down to the exhaust pipe on each end of the header collectors or after the catalysts if you're running cats. I have no problem with this as a way to get the blowby gases out and frankly that would be a much cleaner way than to use the intake manifold to suck that crap back in through the induction system, back into the intake runners and into the combustion chambers and through the exhaust. My opinion and you know what they say about those.
Agreed!

I have LS9 valve covers. Two 10AN breather fittings. 10AN Y to single 10AN into the side of a MightyMouse catch can. Their remote exit lid on the top going down to an exhaust extractor with a 0psi check valve in between.




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Old Feb 23, 2026 | 07:40 PM
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Clean looking setup you got there sir.
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