Crankcase ventilation

[speED]

Despite all my efforts, running a PCV valve just will not work. The engine is a BBC with a stud girdle .400 from the valve cover. I have tried different baffles, grommets, and restrictions. I used to suck 1 qt. in 50 miles. With the current baffle system I now consume 1 qt. in 150 miles. To run an air/oil separator would mean I would have to basically drain almost every time I take the car for a ride and there is no easy way to have it self drain. When I run breathers my oil level stays at full. In order to end the frustration I was thinking of running a hose from each valve cover to a catch can with breather. Is there anything out of the ordinary i should know - never used one before.
Thanks,
ED


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[rchaskin]

Man your motor really sucks......lol, I had to say that.

I ended up doing that very same thing.

It does work, and catches some nasty water gunk. It smells horrid.

The only drawback, is that it realy gets the area around the canister nasty. I have to wipe it off pretty frequently.

You will also need a 1/4 turn ball valve like this to make draining easy.
http://www.compressor-source.com/3_8...8mf-single.htm

Here is my setup.

[cluxford]

Yep, 632 BBC baffles and stud girdles, I run same set up, twin catch cans one from each rocker cover. It smells a LOT, especialy when driven spiritiedly but never have an issue

[nokones]

On my old L98 the pressure use to push the dip stick up and blow oil out of the tube. Also, the throttle body would suck some of the oil. I also had a breather catch can installed with a hose from each valve cover to the breather. The PCV had to be scrapped. After the installation of the breather, the problem was resolved and the breather catch can pretty much stayed dry.

[speED]

Thanks guys, greatly appreciated.

[LemonTwisted]

Here's a good read on high performance crankcase ventilation:

https://www.shophemi.com/images/medi..._ccv_bible.pdf

[speED]

Steve,
Excellent read. I just don't understand why they did not address in more depth how the stage 3 setup works. What I'm referring to is they moved the location of the vacuum source from behind the throttle plate to in front of the throttle plate. This functions totally opposite of the original factory design. Ported vacuum and manifold vacuum are not the same - the systems are actually working opposite of each other. I never thought of plumbing it this way, I think it may actually help my oil consumption a lot.
Thanks,
ED

[yellow1098Greg]

Great thread and right on time....I was thinking about running one hose from my valve cover to the catch can and leaving the other with fresh air...would this have any benefit? I thought having fresh air on one side would have a benefit...just a question...prob a stupid one...thank you!

[speED]

Great thread and right on time....I was thinking about running one hose from my valve cover to the catch can and leaving the other with fresh air...would this have any benefit? I thought having fresh air on one side would have a benefit...just a question...prob a stupid one...thank you!

I don't see any benefit to run a breather on one side only, pressure should basically just be exiting from both sides due to lack of a vacuum source. I believe the outside of the valve cover will get dirty on the side not plumbed to the catch can. I have decided to run both valve covers to a catch can. I was going to try the stage 3 plumbing mentioned in the article but after some consideration it raised more questions. For example the article mentions the importance to circulate clean air into the crankcase, but there is no accommodation for that in the diagram??????

[yellow1098Greg]

So does just running a catch can with hoses from the valve cover breathers nessisary help with anything besides catching oil coming from the breather? (Which I will still do) I was hoping to add some additional crackcase relief to the PVC system I'm running now. I have the pvc with fitting in the front on my intake plumbed to my carb along with the breathers. Would incorporating the catch can to breathers alone help? One scenario I was think about this... would putting one hose from the catch can to the carb and one hose from the breather to catch add some additional relief? (Pontiac 400)

[kimosabi]

Also important to note that all engines does not have equal amount of blow by. If you have an engine from a meticulous build with great ring seal, you won't have much blow by.

[woody80z28]

Great timing! As I'm finalizing my firewall mockup I'm looking at breather tanks and looking for real world experience.

I've read the crankcase bible and I can understand why vacuum in the crankcase is ideal. In theory, I should run a puke tank between the valve cover and the air cleaner on each side (stage 3).

Here are my ideas/questions...

It seems like a large AN-12 line from the pass valve cover to the tank to the air cleaner would be sufficient for all the crankcase evacuation. AN-12 should be even more flow capacity than dual 3/8 hoses. Just seal the hole on the driver side and pull all the vacuum through the pass.

Is the vacuum in the crankcase really necessary in the real world? I do plan to beat on my car (drag, autocross, etc.), and when I do, will it generate pressure in the crankcase with just venting to atmosphere? It sounds like Kenny has gone this route and seen less pressure than when stock with a PCV. Maybe that is really enough and the vacuum generated at part throttle and idle is not all that helpful because there is less blowby at that point.

[yellow1098Greg]

So you would just have one hose going from the passenger valve cover to the catchcan....then a hose from the catchcan to the aircleaner. And leave the driver side can open to the air?

[woody80z28]

I would seal the driver side to try and keep vacuum in the crankcase. If the driver side was open air you'd be pulling air through and still be at regular atmosphere. However, even in that case, under high load you're going to have little to no vacuum when you need it the most.

That's why I wonder if its worth the extra complication. I'm a fan of simple.

[yellow1098Greg]

The other thing I see a lot of is one breather having a hose connected to carb...pulling vacuum I assume...with the other breather open....how does this setup compare to the catch can setup?

[kimosabi]

The other thing I see a lot of is one breather having a hose connected to carb...pulling vacuum I assume...with the other breather open....how does this setup compare to the catch can setup?

That's a standard setup without catch can. That's it.