Car: 1973 2.0 with dual Webbers

Issue: I have a leak from the drivers side valve cover, and poking around, I know my crank & head venting is not correct, which may be what's causing issues. I wanted to fix this first, before I change the valve cover gasket.

I have what I believe is the CB breather box already on the car. It has a hose connected to the oil filler area, one to the fan shroud, and one that is venting to atmosphere.

I have a hose port at the base of the carb intake manifold on both sides, that does seem to vent air out. I assume these are the head or valve cover vents, but am not sure. Additionally, nothing in the system seems to pull vaccuum, unless the fan shroud vent does so.

I have 3 main questions: What are the hose ports at the base of the carb intakes (front of intake on drivers side, rear of intake on passengers side)? What's the correct routing of the hoses? Where does the system pull a vaccuum?

Many thanks in advance!

Its an oil overflow system. Some people swear by them, other say that they are not needed.

oil gets pumped into the heads via the pushrod tubes. The heads can get pressurized and pus the oil up out of the vents, up the hose, and into the breather box. From there it goes into back into the crank case.

Zach

Thanks. I understand the system, just trying to figure out how it applies to a Porsche 2.0, what the ports at the base of the carbs are (I assume these are the valve cover vents), and where the system get vacuum from.

Your description is confusing. A pic is worth a thousand words.

Wait.....your breather bottle is connected to the port on the fan housing?
That port is blowing fresh air and originally used for venting the carbon cannister ontop of the fuel tank. If thats connected to the bottle and the bottle to the crank case port you are basically blowing air into the crank case. (or at best preventing the crank case to vent into the bottle)

Remove the hose to the fan housing and connect it to the carbon cannister or plug it.
Connect the crank case port on the oil filler tower to the breather bottle.
Connect hoses to the head/valve cover vents, join them with a Y-fitting and pull the
joined line to the breather bottle. Put a small air filter on the third connection of the breather bottle for peace of mind.

Hopefully this is correct otherwise I'm sure someone will chime in.

This is exactly the info I am looking for. My other question, are the valve cover vents the ports at the base of the carb intake manifolds on both the driver's & passenger's side? They come off at 45° angles?

Plug the vents from the heads. You don't want them as they will allow oil to accumulate in the valve covers rather than drain back quickly to the crankcase. This leads to lower oil pressure, especially during spirited driving.

You only need one line (1/2" is plenty for a street engine) to breath the engine, and it's best if it comes from the oil filler area.

You do not want to run a line from the fan shroud to the breather can.

Many people route a hose from the top of the breather can to the aircleaner. This has pro's and con's.

Pro's; less mess in the engine bay from the vapors.
Con's; the vapors, if excessive, can gum up the carbs and intake ports.

Len Hoffman

This is in my near future for the 2L race car. I'm collecting a half-pint of so oil per day in 2-3 sessions in my current system. Just gonna let it drain back in...

http://www.tangerineracing.com/crankcasebreather.htm

Hi Len.

I read your and Jakes research about plugging the head vents last year and figured I'd follow that advice for my stock 2.0 with EFI. While I'm not certain it was the only cause I think it may have contributed to my engine puking oil from the passenger side valve cover all over the dyno when I took it to get tuned. (the port on the oil filler tower was connected to the driver side ITB setup.)

Sounds like a leaky valve cover gasket. Warped valve cover, or gasket that wasn't glued into the cover, perhaps?

A leaky valve cover will actually act like a vented head by creating a path to atmospheric pressure, taking oil with it.

Remember that these engines have very strong crankcase pulses that range from a negative pressure to a positive pressure with every crank revolution.

Those high frequency pressure pulses challenge every seal and gasket exposed to crankcase pressure. It's why racers weld tabs in their valve covers to prevent the gaskets from getting sucked inward.

We glued our gaskets to the covers with 3M Weatherstrip adhesive, just like all of my dad's race engines.

It's a universal truth with ICE's, put the sump pick-up at the lowest point of the engine, and breath it from the highest point. Head vents just allow another path to the atmosphere and keep oil pooled in the heads.

OK, GregAmy and Ham say to plug the 45° ports at the base of the carbs, and Falcor said it was a factor in making his engine puke from the valve cover. I have new (cork) valve cover gaskets (Felpro) to put on the engine, which looks like a 10 minute job (I'm sure it's not though), so hopefully, between that, and getting proper venting to the engine, mine will stop puking oil.

Replacing gasket looks to be:
1) Remove spring clip
2) Pull valve cover
3) Remove old gasket
4) Clean both mating surfaces
5) Put new gasket on cover
6) Mount cover on head
7) Return spring clip

Can I use grease to hold gasket on valve cover, or do I need to use something stronger like an RTV? Anything I missed above? If not, it looks to be a 10 minute job.

Afterwards, I need to:
1) Cap both valve cover/head vents
2) Only have host from filler cap area to breather box
3) From there, I can run a draft line from breater to vent to atmosphere below the car, vent to carb, or vent to a K&N filter. I assume venting to carb is more environmental, venting to a little K&N filter will cause a fine oily mess in the engine compartment, and venting to atmosphere would be bad, environmentally, but would be fairly simple, and provide a slight amount of vacuum to the system.

Thoughts, suggestions or advice on what will make this simpler to complete this evening would be greatly appreciated!

You need to glue the gaskets to the covers. RTV is not a good adhesive. You need something with shear strength to keep the gaskets from sucking in. 3M weatherstrip adhesive works great.

I glue the gaskets in and clip them to clean, dry heads to set-up overnight before installing. You can do it on the car if you don't have old heads laying around.

I recommend pulling them back off after they sit overnight to make sure the gaskets didn't slip.

Len

Negative, Ghost Rider. The Tangerine kit takes hoses off each head (to properly vent the top ends) as well as a hose off the port next to the oil fill, and runs them to the container. From the bottom of that container is a drain hose that is plumbed to a fitting at the base of the oil fill box.

I decisively suggest you vent both heads and block to that container.

OK, now I'm confused.
You say vent the heads to the breather can, but HAM says plug the head vents.
Does it have to do with the type of vent can design used ???
Barefoot

I do not vent my heads.
I use the stiock breather box only and increased the size of the vent line and run it to a aftermarket breather box on the firewall (no drain back to engine).

I have never had to empty the collector on the breather box but the engine is a relatively new build with 1-1/2 race seasons on it.

I have zero oil leaks and no problem with the valve covers.

I glued my cork gaskets into the valve covers with Blue RTV (the ONLY PLACE I use RTV on this entire engine any more) then installed them on the engine with a light pressure from the bales (didnt click them all the way on).
I left it overnight like this.
Then I removed the covers and put a very thin coat of blue RTV on the outer (mating) surface of the cork gaskets and let it tack up but not dry.
I then put a coat of oil on the head mating surface and installed the covers.
I have removed/reinstalled the covers more than a dozen times and never had to replace the gaskets and never had a leak.

I asked for some pics. You ignored me. Still no pics. You are on the internet so you have a camera.

No idea why someone is recommending you not use factory breather ports. Is it because their vent/can design does not allow oil to be separated and flow back into the engine?

For example, my current design on the race car is just three 1/2" hoses going into a quart container, with a manual drain on the bottom. I collect 1/2 pint or so of liquid oil in there each day (couple session of hard running). I see no problem with that, it's part of the design. Mine is a brandy new Tangerine build with one track day and one race weekend on it.

However, if this were my street car I'd likely be really annoyed at having to keep track of that can and ensure I empty it regularly so it does not overflow and/or I do not run low on oil (even though I'm running a 10-qt dry sump system so that's unlikely).

I will be installing the Tangerine design, which includes a can that accepts hoses from all three places (both heads and the fill vent) with internal baffling to separate the liquid oil, condense the vaporized oil, and return the resulting liquid back into the crankcase through a fourth fitting added to the fill box. That, in my opinion, is the "correct" way to do it.

I'm not interested in rehashing this subject, but I will set the record straight that I don't sell breather cans.

Did not mean to imply you did (I don't know you or that you sell parts). I refer to "their can" as the one installed in "their" vehicle.

Not a challenge, simply an opinion. If the "problem" is that venting the heads collects oil in the cans, then the solution seems to be to separate and drain the collected oil back into the crankcase.

No biggie. If I did sell cans I would sell them for both configurations since opinions on this are split.

It's worth noting that VW/Porsche did away with the head vents in 75. No T4's have them after 74.

Vent/ don't vent. It doesn't matter to me.

I don't know if it's relevant (or even accurate), but if memory serves 1975 was a milestone year for implementation of US emissions regulations, including I think catalytic converters and PCV systems.

What is the reason(s) for blocking off these head vents?

Greg

http://hamheads.com/type4-test.php

This is how I setup my car. Did 10 hours at Sebring and never had an issue with oil coming out of any vents. Thanks Len!

Lately I have had good luck with a balance tube between both head vents, not connecting it to anything... Just bridging both heads together.

Thank you, that's quite useful info. I agree with the methodology, concerns, and conclusions, especially in regard to the pressure differentials and its effect on oil drainback (a concern that I share).

So (if I infer correctly) the suggestion here is to, effectively, allow the top end to "pressurize" in order to minimize the pressure differential between top and bottom end, which allows better oil drainback to the case. As a result, however, that add'l pressure can cause valve cover leaks, which is addressed by better gaskets and/or glueing.

On the flip side, the root symptom that led to this testing is collection of oil in the top end which was getting spit out into the overflow container. The alternative "solution" is to collect, condense, and drain this oil back into the bottom end.

I'm not sure I share the concerns about putting this breather oil back into the case; after all, if this is truly "oil that is pumped into the rocker chambers via the pushrods is aerated by combustion gasses" then that also exists with the oil that's being drained back when the vents are blocked.

This may be a case of "six of one, half dozen of another". My personal preference at this time for the race engine is to lean toward allowing the pressure to bleed off, then collecting, condensing, separating, and re-introducing the oil back into the case. However, I now recognize the value of the "block it" position, though I'm concerned leaving any significant pressure in the top end (has anyone stuck an air pressure gauge in there just for funsies?)

For the street, given reduced chance of significant long-term high-RPM use, I'm thinking the "block it" proposal would simplify things a ton, as long as you focus on getting those rocker boxes sealed nice and tight. Oil leaks suck.

Greg

This thread is very timely for me. I just installed a 2056 with dual carbs. I have the passenger side head vented only through a filter and the driver side head and chimney vented together through another filter. No catch can is used at this time.

I have 2 issues:

1) The passenger side head vent is dripping oil on the engine and making a hell of a mess on top of the engine and below it. Very little oil is coming out of the driver side head + chimney vents.

2) Gasses from the filters from the crankcase are being sucked back into the cooling fan and eventually into the interior when cabin heat is on. I've mounted the filters next to the carb filters to try to get the gasses to be sucked back into the intakes. Positioning the filters next to the carb intakes work ok when the throttle is open. When the throttle is closed on deaccel, I get very noticeable vented burnt oil odor in the interior.

I'm looking to solve both issues.

From Len's and Jake's findings, it sounds like I can connect both head vents together with a straight hose. Then add a filter to the chimney. Should the chimney filter also include a catch can? The chimney filter should then vent the crankcase gasses back into the carb filters to keep the gasses from entering the cabin during heating season (about 1/2 the year here in PA).

Comments? TIA

Sounds like your factory vent tubes are loose. They're very thin wall aluminum tubes that are just pressed into the heads. It's very common for them to come lose. It's also common for them to crimp and/or bend when hoses are installed and hoseclamps over tightened.

The tubes will usually come out without a fight. You might be able to pull yours out with the hose. Leave the hose tight on the fitting and yank it.

The opening in the head can be easily tapped for 1/4" npt fitting with no drilling required. Then you can install hose barbs if you want to stay with vents, or just install pipe plugs if not.

Gents
I have been running the "dog" out of a type 4 in a vintage race car for about 10 years now. It has 11.7 compression, 318 degrees of duration on the cam and is never babied. Listening to Len at HAM has saved time, effort, and embarrassment. He understands the oiling system and how it all works. After venting the heads to a fancy extra can, I closed off the heads and vented only thru the oil filler. The results were much better. He has done nothing but do right by me. Do as you please...it is your car. But, in my 66 years, listening to experience and integrity is beneficial.
old914dog

When FAT Performance built my engine this is how they set it up. A breather box high on the fire wall. A hose from the box to both head vents and a third one to the oil filler vent. I've never had trouble with this set-up but your saying I can remove the hoses from the heads and block off the head vents?

If you have a CB box, do *not* leave one hose open!
The box already has a build-in filter and venting inside the top lid.

When i had my carbed 2056, i had 3 hoses on my CB box (4th port was blocked off). One to each head vent and one to the oil-filler neck which lets the oil drain back into the filler neck.

The head vents have both positive and negative pressure, depending on the rpm and load on the engine. Meaning they do both, suck air and blow air.

I used Andy's setup for years and always had a slight oil film below the cbbox. I added another hose from the box to the carb and issue went away. Not sure if right or wrong but it worked.

I've never been one to tell someone to stop doing something that's working for them. If it works and you're happy with the arrangement, rock on.

But if you ever notice low oil pressure in corners during track time or spirited driving try pluggin the hoses from the heads and cap their inlets to the breather can and see if it helps. It usually does.

Easy enough to try and easy enough to undo.

BTW, while I recommend to all of my customers to not run head vents, I still go through the trouble to machine pipe threads in my new heads for folks that prefer that system.

To each their own.
Happy motoring