Venting covers?

[Trevor Pippin]

Getting ready to set up the crankcase breather system on my 2332 and 'am wondering if it's necc. to vent both valve covers or just the 1/2 side. I have heard the talk of  #3/4 side filling up under high RPM and pushing oil into the breather hose. I'm running the CSP breather/filler on the alt stand. Would it be advisable to just vent the 1/2 side and also put a filter in one of the breather tower ports? BTW, I'm running an FI case so I don't have a fuel pump hole to vent from so the valve covers are my only source to vent from.

[Ohio Tom (DdK)]

It is best to vent both sides or you will likely suck a valve cover gasket in and have oil leak issues.

[Glenn]

Do both.

[bowen71]

Is venting really needed?  Its rare for me to rev over 5500rpm. 

[neil68]

Hey Trev,

For a couple years, I got away with only venting the 1/2 cover to my tower breather (not CSP though).

Then when I increased the shift points to the 6,500-7,000 rpm range (Web 86C/226), 44 valves, etc, I added a CSP box on the firewall and tapped the 3/4 valve cover...problem solved.

Your CSP tower is larger than mine, so it might be able to handle both vent hoses.  Hope to see your 2332 cc in action next season

[BeetleBug]

Why would you vent your valve covers? You should vent where the pressure is created - your crank case. If you choose to vent your covers you will only open up a "highway" for the oil to move freely up to your heads. When the head(s) are filled up the oil will continue to follow the easiest route which is..... your breather line. Why? because the oil is not allowed back to the engine case through the 4 lines it should use (pushrod tubes) due to the pressure inside.

I stopped venting the valve covers and instead I`m venting the crank case where it is vented originally + from the fuel pump cover. You could modify the engine case inside for it to vent more effiecently but that is a much longer story. Oh... 2332 turbo/efi engine.

Best rgs
BB

 

[Mike Lawless]

I'm with BeetleBug on this. Read his post carefully, think about the physics of it all, and that is exactly what happens.

Bottom line, vent where the pressure comes from and you will keep the oil where it will do the most good. In the sump. Vent the VCs and you will provide a low resistance path for oil to go where it does no good at all. Up the vent lines and into the breather box and NOT in the sump.

I know there are a lot of guys who swear by venting the VCs and that's OK. I reckon people gotta make their own choices. In most cases, you won't see the detrimental effects until you are up past 8000 rpm, at which point the oil pump will be sucking air and not solid oil because all the oil is in the heads and breather box.

[Trevor Pippin]

I do see what he is getting at.
So would I be safe with JUST the baffled CSP breather tower with a filter on top so it can breathe?? Like I already mentioned I can't vent the case from the fuel pump hole cause there isn't one, and it's too late to drill a hole there cause it's already assembled.

[Mike Lawless]

I would think you'd be OK with that Trevor. That's the only outlet I vent my case from, (#10 from filler tower to 2 qt box with breather hose attached to one way check valve on the header collector) and I'm going 8500 rpm.

The only drawback to having a breathing apparatus that vents into the engine bay is the potential for oil mist. I'd imagine the breather tower is baffled, so it shouldn't be a problem.

[1836vw]

It's pretty hard on valve cover gaskets when there is no venting.

[BeetleBug]

Glad to read that we agree Mike.

[BeetleBug]

It's pretty hard on valve cover gaskets when there is no venting.

I would have to disagree. If you experience issues with your VC gaskets then I would say you have a problem somewhere. If you do not have enough ventilation you will experience oil leaks but remember, the oil will always take the easiest way out and my guess would be the front pulley, flywheel seal etc etc. It will not climb UP to the heads and cause the gaskets to leak - unless you have a breather line there.

[BeetleBug]

I do see what he is getting at.
So would I be safe with JUST the baffled CSP breather tower with a filter on top so it can breathe?? Like I already mentioned I can't vent the case from the fuel pump hole cause there isn't one, and it's too late to drill a hole there cause it's already assembled.

I`m using the CSP tower breather and I`m very happy with it. But I have opened it up as much as absolutely possible where the filter is (40mm). Please note that on the picture I have not sealed two of the inlets.

Best rgs
BB

[1836vw]

I would have to disagree. If you experience issues with your VC gaskets then I would say you have a problem somewhere. If you do not have enough ventilation you will experience oil leaks but remember, the oil will always take the easiest way out and my guess would be the front pulley, flywheel seal etc etc. It will not climb UP to the heads and cause the gaskets to leak - unless you have a breather line there.

I would think that you would have equal pressure on bothsides of the piston rings.  How would you size the pistons backside pressure?

[BeetleBug]

I would think that you would have equal pressure on bothsides of the piston rings.  How would you size the pistons backside pressure?

Not sure if I understand you correctly but my point is that you have equal pressure all over the line, heads and crank case. That is until you "mess" up this balance by adding a breather line. Do you think you can have too much ventilation in your crank case? I don`t.

[Bugorsh]

So with a dual carb'd motor if you leave the vc's alone and you're venting from the fuel pump hole to the breather tower and from inside the alt stand.  What about running hoses from the CSP breather tower to the air filter cover plates so the carbs are creating a reduced or negative pressure inside the case.

[Mike Lawless]

That would be a good way to go to keep the engine by cleaner as any mist would be drawn in and burned rather than oiling up your engine bay.

[superdrag]

So with a dual carb'd motor if you leave the vc's alone and you're venting from the fuel pump hole to the breather tower and from inside the alt stand.  What about running hoses from the CSP breather tower to the air filter cover plates so the carbs are creating a reduced or negative pressure inside the case.

Thats how my Kads are on my street car.

[martin]

What about running hoses from the CSP breather tower to the air filter cover plates so the carbs are creating a reduced or negative pressure inside the case.

This would be good for emissions, and bad for performance. Oily mist doesn't burn well.

[Ohio Tom (DdK)]

I'm with 1836 on the valve cover gastket issue.

I hear what you are saying about keeping the cover un/vented. And it all sounds right to me.
However, I see the issue as something different.
It's not the pressure blowing the gaskets out, rather it's the vacuum sucking them in. Without the vents, the valve cover is subject to the crankcase pressure. Whether on, or off the throttle.
I believe that this back and forth pressure works the gasket in and out.  
Take your foot of the gas at high rpm and the valve covers will see vacuum.
This sucks gaskets inward. Then, they leak.
Even stock bails with good surfaces.
I have battled this issue on many motors in the past before settlings on venting them.
When I vent, I don't see gaskets getting sucked in any more.

Now if you are running some autocraft heads with cast valve covers with 6 studs holding things in place, then no need to vent.


I am a strong beliver in case porting. The ability of the botom end to "breath" greatly reduces pressure fluxuations and oil misting.
This seems to keep the oil in the sump better than any other trick I have done.

[BeetleBug]

Interesting, I have never had a issue with sucking the gaskets and I have used a lot of different covers. Currently using original ones on my CE head. The gaskets are mounted dry and have not leaked one single drop of oil.

[bugnut]

Venting the case at the fuel pump location is only an option if one seeks or is able to run an electric fuel pump.  For my engine combo, I'm electing to keep the stock mechanical pump, so realistically the only option is to vent the valve covers and the oil filler, but I also won't be turning upwards of eight grand, either. 

Seems to me there's solutions for street cars and also applications for race cars.  Opinions vary, of course, but for me 8K RPMs isn't a realistic range for a street motor... at least not for very long.  Lol.

[Mike Lawless]

Well, like I said before, everyone has different ways of doing things and valid reasons for doing so. All one can do is weigh the different options, try one and see what happens. If it don't work out, try something else. All it is, is a little bit of work. It's not like anything you try is irreversible.

I have a set procedure for everything I do...
Try the simplest solution first.

[neil68]

Venting the case at the fuel pump location is only an option if one seeks or is able to run an electric fuel pump.  For my engine combo, I'm electing to keep the stock mechanical pump, so realistically the only option is to vent the valve covers and the oil filler, but I also won't be turning upwards of eight grand, either. 

Seems to me there's solutions for street cars and also applications for race cars.  Opinions vary, of course, but for me 8K RPMs isn't a realistic range for a street motor... at least not for very long.  Lol.

My situation as well, I run the stock fuel pump and was using a breather tower vented to the atmosphere, then later added the 1/2 valve cover vent.  This was fine into the 14-second range, but once I started winding the revs up to 6,500-7,000 rpm, I needed to vent the 3/4 as well.   No problems ever since.

[bugnut]

At this point, my plan is to vent both valve covers plus the atmospheric vent of the oil filler to a Clyde Berg breather box.  Hopefully that will suffice for my application for the time being... if I ever get the damn thing built.  Lol.

[Bugorsh]

Does anyone have picts of the case porting?  I am about to do some mock ups for final assembly on my 2332 and would like to port the case before final assy.  I have an idea as to where to port it, but seeing some picts would go a long way toward doing it correctly.

[Alexander_Monday]

It's not the pressure blowing the gaskets out, rather it's the vacuum sucking them in. Without the vents, the valve cover is subject to the crankcase pressure. Whether on, or off the throttle.
I believe that this back and forth pressure works the gasket in and out. 
Take your foot of the gas at high rpm and the valve covers will see vacuum.
This sucks gaskets inward. Then, they leak.

How about an old and cheap trick we used in the 60's & 70's on the FE ford big block?

The FE did not have anything to hold the cork front or back intake to block gaskets except sealer and invariably they would blow out with a good backfire.  If you have ever worked on an FE you know what a pain it is to remove and reinstall the intake.  So, we would drill small holes about 1" apart along the length of the block front and back surface, pound a short piece of coat hanger in, and cut off with side cutters leaving just enough point sticking up to hold the gasket in place.  ( Credit to my old man, he knew a trick or two  )

[javabug]

breather hose attached to one way check valve on the header collector)

After I saw Damon Lieutia's (sorry for the spelling) oval in HVWs with the header/breather setup I've been curious about that method.

[The Inspector]

  you could always go with a Vacuum pump......

[Sam]

I ran clear hoses on my engine for a while and no oil goes up the valve cover vents.....    The most oil I could see was a constant spray up the vent where the fuel pump used to be. 

Valve covers fill with oil all the time, haven't yall seen the guy that cut a hole and put plexi glass so you could look into the valve cover?   

THink about this, besides not leaking oil adding the vent lines to the valve covers is like haveing a tank vent, it helps the oil flow back into the block better. If your crankcase vent is nice and open it should be the path of least resistance for air to escape.

I would agree though that VC vents are useless if you not going to rev past 5500, unless your going to hang out above 4000 for long periods of time

[superdrag]

Valve covers fill with oil all the time, haven't yall seen the guy that cut a hole and put plexi glass so you could look into the valve cover?   

I believe that was Mike Sheldon.  He posted pictures at different rpms.  Like "This picture is 3000 rpm, this one is 4000", etc, etc.

[1836vw]

Old school on a steel valve cover.  Use a center punch and make dimples down the center of where the gasket surface is.

[John P]

Interesting discussion. I can only comment on own experience.

I ran a mild 2017 with IDAs for 10 years without any additional venting, aside from running a stock line from the breather to the right side carb intake.

6 years ago the 78.4 mm crank was swapped out for an 82 mm crank and a lightened flywheel (along with a cam change), and things changed. My first pass at the track nearing 6K at full throttle created a mild, James Bond effect. My theory was that, with the longer stroke crank and lighter flywheel (quicker acceleration), more crankcase pressure was created. I needed a solution.

I run my stock fuel pump, so the top of the case was not an option. I run stock, vented valve covers with stock VW cloth breather line to a Berg breather tower. The breather is then vented to the velocity stack on the #1 intake on the IDA.

No oil is getting up there, and I no longer emulate James Bond. No leaks. 

My 1.5 cents.

JP

[BeetleBug]

Interesting, so you "blame" the bigger crank for increasing the internal pressure. I attended the JPM dyno day event last weekend and I noticed that he did breath from both the valve covers with huge hoses (18-20mm) together with even bigger hoses from the fuel pump cover and the alternator tower. I asked why and he told me something I found very interesting. He said that he believed that the springs would last longer due to more oil/oil "steam" inside the valve covers and that was the only reason. Mind you that he build street engines that revs 9500 - 10 000 rpms. His 1915 dyno'd 248 hp at 9600 rpms (NA)

The original alternator tower have a 16mm hole + the 10mm hole on the original oil filler "box". That equals 9 AN6 hoses or 5 AN8 hoses. in other words, it is very hard to match the original breather system.

[John P]

It's a theory, but all 4 pistons are physically moving further each stroke, increasing the pumping action inside the case. Plus, with the lightened flywheel, bigger cam and more compression, the engine accelerates MUCH further. It was the same engine, otherwise.

The simple fix solved the problem.

247 HP out of a 1915? Insane.