Help me build a better pcv system

[DarkoNova]

So right now I just have an AutoZone pcv valve in the passenger side valve cover going into the carb. Along with a push in breather on the driver's side valve cover.

The pcv valve has a baffle in the valve cover. The breather has no baffle.

The breather is just a generic AutoZone breather and it really doesn't fit snug at all. It's fallen out of the valve cover numerous times. My buddy wrapped the base of it in electrical tape to make it a snug fit.

I barely broke in the engine maybe a month ago and have driven it for maybe two weeks. There's already a coating of oil on the top of the driver's side valve cover.

I've been looking into catch cans, oil/air separators, and even an adjustable/tunable pcv valve.

I'm just not sure the best way to route everything.



Pictures/opinions/advice are welcome.

Engine is a roughly 10.5:1 sbc with a solid flat tappet cam.

[Turbo6inKY]

I had huge PCV problems. I'd pressurize the crankcase and blow oil out of the dipstick tube. It made a huge mess. I conquered my PCV issues a couple of years ago. My suggestion for you is what I did. It might be overkill, but it works.

You want these grommets:
https://www.summitracing.com/oh/part...e1-_-mr-gasket

They really cut down on the oil splash from the rockers getting into the breathers.

And you want these breathers, one in each valve cover:

https://www.summitracing.com/oh/parts/mrg-2063

Run the lines from the breathers to a catch can, then to the intake tract ahead of the carb inlet or throttle body. If you're using a MAF based system, that hose needs to be between the MAF sensor and the throttle inlet. If you're speed density or carb, tap it into the intake tube after the filter or into the air cleaner if you're carbed.

Second, run the "regular" PCV circuit from the PCV valve to another catch can and to the PCV port on the intake. If you're turbocharged, put a brass check valve on this circuit to back up the PCV valve, since they tend to leak under boost. You want the check valve oriented so it's open when gas is flowing from the crankcase towards the intake.

In normal operation, the normal PCV circuit will draw air through the breathers from the intake tract, then through the OE PCV valve, and into the intake as the factory designed. When you put your foot in it, the PCV valve closes and the flow reverses. Air moving into the throttle body/carb will draw the vapors from the valve covers through the breathers, through the catch can, and into the intake to be reburned. The catch cans will get all the liquid, so you're not going to make a terrible mess of the intake tract, though you will want to clean it every few years, but you probably do that anyway.

[parsonsj]

I wrote this in my build thread about how I used dual Pro-Vents.

https://www.pro-touring.com/threads/...86#post1122886

[$Mike70Z-28]

i installed the moroso valve cover baffles in my covers cause they didnt have. i also installed a moroso oil separator

[$Mike70Z-28]

[CarlC]

I wrote this in my build thread about how I used dual Pro-Vents.

https://www.pro-touring.com/threads/...86#post1122886

The Pro-Vent is an awesome piece and works like a true OEM part should. None of draining and/or steel wool, but a real "filter" , pressure relief valves, tangential entries, etc. There's nothing like it in the aftermarket.

[Typhoon1015]

check out MightyMouseSolutions. He has a catch can setup with breather and PCV integrated that should do the trick!

[parsonsj]

a catch can setup with breather and PCV integrated

PCV systems require engine vacuum to work. Breathers along the vacuum path defeat that basic premise...

[Typhoon1015]

PCV systems require engine vacuum to work. Breathers along the vacuum path defeat that basic premise...

I understand the principals for how a PCV system works.

His setup has a weighted piece of rubber which acts as a valve of sorts, so under vac, it seals and the can is essentially a sealed catch can for PCV. Under boost or excessive crankcase pressure, it vents through the filter and the PCV is fully closed.

[parsonsj]

His setup has a weighted piece of rubber which acts as a valve of sorts, so under vac, it seals and the can is essentially a sealed catch can for PCV. Under boost or excessive crankcase pressure, it vents through the filter and the PCV is fully closed.

I'm not directing that comment to you in particular , but the many readers of this thread. I've seen many many PCV systems with a breather stuck on the valve cover or the catch can because guys think it helps, when it actually keeps the PCV from working at all.

I'll agree the MM system is certainly better than simply sticking a breather on the catch can, but ... when engine vacuum drops and/or crankcase pressure is high, the PCV valve should close, preventing crankcase vapors from even flowing through the dirty side of the PCV plumbing, which makes the breather unnecessary to begin with. In such systems, the flapper valve under the breather is just something that might fail, causing problems down the road.

In orifice systems (there's no valve that closes) when crankcase pressure overcomes vacuum, the catch can should be sized and able to remove oil from the vapor, and allow the vapor to be burned by the engine, rather than vent it to atmosphere.

Crankcase vapors will also flow back through the clean side at higher crankcase pressure (and guys stick breathers there too!) and back inside the intake tube to join the intake air. If all the plumbing is done right, there's no need to vent the vapors to the atmosphere. If one is concerned that the vapor will oil down the intake tube from clean side reverse flow then the right answer is to put a catch can there too. Again, no breather is needed, just proper plumbing and can sizing.

A final note is that allowing intake air to vent to the atmosphere through the PCV path can cause tuning problems on MAF-based EFI.

[Motobrewmaster]

John, Do you agree with the Arrington Performance CCV bible?http://www.speedtechperformance.com/...entilation.pdf

I am also a bit confused by the instructions for the ATS LS7 dry sump setup. The catch Can is a Peterson Breather can. http://www.petersonfluidsys.com/breathercan-LS7.html

http://www.speedtechperformance.com/...an_Install.pdf

This seems contrary to what you are saying.

I have this setup but have not installed it yet and would love to hear your thoughts.

PS. - I looked at the ProVent stuff. Very nice and I like the OEM design and look.
PPS - The job you did on the LS9 69 is AMAZING!

[parsonsj]

Moto, The CCV information is the same as what I thought I wrote above, in a lot more detail. Can you explain what you mean by "contrary to what you are saying"? Maybe some clarification will help?

The Pro-Vent stuff has 3/4" inlets and outlets, swirl chambers, and genuine OEM quality filters to remove oil from crankcase vapors / air. I also like the ability to remove the tops by hand for filter inspection.

[Motobrewmaster]

John,
I mean contrary as in they are recommending a breather in the PCV system. Please look at the attached diagrams they provided. I think where the Peterson Breather is connected to the PCV lines to the valve covers and the intake would not work if I understand correctly. It seems that this should be a closed oil/air separator such as the ProVent type (150 maybe).

I think the breather -12 AN line from the top of the oil sump tank to the breather would be fine. My dry sump system is a factory LS7 type on a modified LSA block using a Katech High Capacity Scavenge/Pressure Oil Pump (67-KAT-A5069-LS9). I am not sure if that pump will help to pull a slight vacuum on the block or not.

I was also wondering if I should put an oil separator into the line connecting the valley pan to the intake?

Hope I explained myself ok.

Cheers, Steve

[parsonsj]

Steve -- I don't know what the Peterson breather does... It seems as if it's operating as an oil/vapor separator, which might be useful. I would think the ProVent might be a better part, but I don't know that.

And yes: if you can make the plumbing work, an oil separator (or a catch can) there is a good idea. The space is tight, but I did that for my Z06 with its ARE external scavenge pump.

The other thing I'd recommend is a drain back to the oil pan, if you can. I've welded bungs to pans, and I've also adapted the pan drain plug to a 6AN banjo fitting for drain back. It's so much more convenient than draining your catch cans.

[DarkoNova]

John, do you have pictures of your setup? I'm trying to visualize how to apply your setup on an SBC as opposed to an LS.

Do I need a breather on the opposite valve cover?

I was always told you want a pcv valve on one valve cover and a breather on the other so that as the pcv valve sucked air from the crankcase, the engine would be able to draw fresh clean air in.

[parsonsj]

I was always told you want a pcv valve on one valve cover and a breather on the other so that as the pcv valve sucked air from the crankcase, the engine would be able to draw fresh clean air in.

Yes, that's right. And if your system is carbureted or doesn't use a MAF sensor, then that's all you need. The only minor thing is to think of the "breather" as a "filter". It's real job is to provide clean air to replace the dirty air pulled out by the PCV.

As far as pictures go -- look over my LS9 build thread. It might be overkill for a simple SBC PCV, but the basic premise is no different than what you've said above.

[DarkoNova]

What if I put a fitting in the opposite valve cover and just ran a hose to the base of the air cleaner? Basically like a stock air cleaner would have.

I'm just wondering if maybe that would be better than a tiny little breather.

[parsonsj]

That's how most of the early OEM systems did it: use the engine air filter for the PCV inlet air. That will work great.

[DarkoNova]

Which pro-vent did you go with? I don't think I saw it mentioned in your build thread, but I may have missed it.

It kind of looks like a 200, but I'm just guessing.

It looks like they all have ports on the bottom to drain, so is it safe to assume I can weld a bung on the oil pan so the pro-vent can drain to the oil pan?

[parsonsj]

Matt, yes, I use the 200s.

You can weld a bung for oil return to the oil pan, but make sure you put a Mann-Hummel vacuum operated one way valve in to prevent vacuum leaks to it from the PCV dirty side.