Valve Cover Breather Pipe?

[Bret]

Hi Guys,

I need some suggestions & ideas for putting a breather pipe on an Alloy head I picked up. Referring to the picture below (compliments of www.mgbexperience.com) the pictured valve cover appears to have came with a breather pipe.

Alloy head w/breather tube

Problem is – the one I picked up is almost exactly the same as the one pictured but it doesn’t have a breather. So I guess I need to be creative, but I don’t want it to look stupid or like something the mullet brothers would do.

Any idea’s welcome?

 

[Guest]

This fix might sound a little hoky to some people but the one in my cover has a small hole in it that may have to be that size to keep too large amount of fumes from going through. So if you don't want to do this to your old cover, maybe you could find another and cut the pipe off of it and flare the end that would be inside the cover and use J.B.Weld to put it in the side of the new one like the picture you have there. You could put the JB weld on the end of the tube where the flange is and slip it through from the inside so the weld wont show on the outside and look messy. If you are not familiar with J.B. Weld, it hardens so hard engine blocks have been repaired with it. It takes 6 hours to set up so you have to take a lot of time.
If it wasn't for this small hole possibly having to be there you could just something threaded with a nut on each side like a pipe fitting if there is enough clearance on the inside to the rockers.
Maybe I am too close a kin to the Mullet Brothers.
Bob

[ 03-13-2004: Message edited by: mrbassman ]

[ 03-13-2004: Message edited by: mrbassman ]

[ 03-13-2004: Message edited by: mrbassman ]</p>

 

[aeronca65t]

Will the vented tappet cover from one of the older engines fit? This would look "factory" and would accomplish the same thing.
If not, you could buy a threaded brass pipe nipple (about 3/8" ID) at you local hardware store along with two threaded collars (these are like nuts).Drill a hole in valve cover big enough for the nipple to fit though and use the threaded collars to hold it in place. Threading the valve cover (if you could get the correct size pipe tap and tap drill) and screwing the pipe nipple into the cover might look nicer. Any machine shop should be able do this for a modest price.

 

[Bugeye58]

Bret, I can think of two alternatives for you.
Vicky Brit offers two of the aluminum valve covers with the breather tube already in place, one for '62-'63, and one for '64-'80. About a hundred bucks.
Or, have someone turn a breather tube from aluminum, and thread one end to a common thread, say, 5/8" x 18. Drill and tap the cover to accept it, and thread it in using some loctite, and you should be good to go. The side wall thickness of the valve cover in the area where the tube is shown in the picture should be in the neighborhood of 1/4", plenty to accept enough thread to be secure.
Surely you must know someone with a lathe handy that could do it for you?
Or, send me the dimensions you want, and I'll spin one up for you and drop it in the mail.
Jeff

 

[Bret]

OK I think I got it figured out.

I did a little poking around at the local NAPA parts store and purchased a generic PVC valve & grommet. Then using a small fine bladed hacksaw, I cut-off the backside of the PVC valve to remove the one-way float valve & spring. This gave me a clean bi-directional opening. Next I looked through my hardware junk coffee cans and found what looked like an old bolt crown that fit perfectly in the PVC housing that once held the valve. I then drilled out the crown with the smallest bit I had – and viola!

Now all I need to do is drill a 1” hole to accommodate the PVC Grommet, in the side of the Valve cover. It’s a shame to have to drill a hole in such a pristine aluminum valve cover, but if I want to pass smog I don’t have a choice. But I think it will look nice & clean when I’m done. So much so that I doubt that the Mullet Brothers will never know the difference.

I’ll post some pics when I’m done.

[ 03-13-2004: Message edited by: Bret ]</p>

 

[Dave Russell]

Just a quick question.Many breathers incorporate an oil separator/baffle inside of the cover. Does your application have a separate separator external to the cover or does the cover need some kind of separator in it? It prevents blowing all of the oil out the vent.
D

 

[steve99]

I agree, even a wad of steal wool as long as it is in there in such a manner that it could not fall out.

 

[Andy Blackley]

Bret: Which carb set up are you using? With the arrangement shown in the picture you posted the breather line is going to the evap cannister, which provides a filtered source of make-up air, i,e the air that will be drawn into the engine. On the earlier cars, like my 69, this is done via a vented oil filler cap. With the SU setup, from 69 onwards, the crankcase fumes are drawn through the front tappet side cover and into the carbs via the "Y" hose arrangement to each carb. If you have this type of SU all you need is a vented oil filler cap. If you dont want to use a vented cap the line from the valve cover should have a small orifice to control the air intake. The Haynes manual has a good diagram of this in Fig. 3.34.

If you have a Weber then things get more complicated. Some people connect the front cover pipe to the bottom of the Weber air cleaner, which is not really correct. A connection from the air cleaner to the valve cover, to provide filtered intake air for the crankcase, would be fine, but the Weber lacks a good PCV port to provide the right kind of suction to draw crankcase fumes out of the engine. Years ago, on 73B with a Weber, I installed a Smiths "mushroom" PCV valve on the Pierce manifold to provide correct Positive crankcase ventilation.

 

[Bret]

Shas-bot!!!

I’m running the “stock” single Zenith Stromberg set-up on my 78B. Here in California we have to be smog checked every two years until the car is 30 years old. To see what I’ve got – click on the link below to see my B’s engine bay before the alloy valve cover.

Old ZS Engine setup!

Anyway all I wanted to do was attach the breather tube in the same manor show in the previous image. However in my excitement to install the new valve cover I made too large of a hole. The grommet said it would work for a hole up to 1.22in dia. Well they lied – word of caution never believe the “stated” inside diameter of anything. But it’s nobody else’s fault but mine because I should have measured myself.

For now the Grommet fits (loosely) and will work but I now need to think of a way to correct my mistake. I’ll update you guys when I figure out what I’m going to do.

[ 03-13-2004: Message edited by: Bret ]</p>

 

[Dave Russell]

Bret,

I think thay Andy is correct. I quote a reference from the following:
https://www.mgbmga.com/tech/mgb9.htm
Carb. control system (1969 onwards)

"With the introduction of this system, the front side plate
cover outlet was now connected to the "Y" fitting from which hoses are routed to each individual carburetor. These carburetor connections are positioned between the piston and the throttle disc. Gases are drawn from the crankcase via the depression in this chamber. Increased throttle disc openings along with increased depression in the chamber allows a greater volume of gases to be drawn into the inlet manifold. The oil filter cap, as mentioned in the previous paragraph, is retained and works on the same principle. In 1970 a non- vented oil cap was introduced with breathing now taking place through a charcoal canister. This system stayed in effect until 1974, and was retained for the Zenith Stromberg carburetor equipped vehicles (1975 onwards). A redesigned front side plate cover was introduced on 18V engines to provide better oil separation and drain-back."
=============================
Also Bob is correct about the restrictor hole in the pipe:
Quote:
https://www.mgbmga.com/tech/mgb3a.htm
11/06/01 VENTING PROBLEMS

"NOTE: The 1⁄2” hose restrictor which, may or may not be supplied with your kit, allows for adequate breathing on a well sealed engine. For engines that have above average “blow-by” conditions, the 1/16” hole diameter can be enlarged to the following: 5/64” 3/32” 7/64” or 1/8”. It should not be necessary to exceed 1/8”.

Obviously, the larger the hole within the restrictor, the more chance of oil transfer to the induction system.

We recommend installing the hose restrictor with the original 1/16” diameter hole first, then monitoring for excessive “blow-by” conditions. These conditions will be manifested by oil being blown out of several locations on the engine. These locations can be the oil dipstick tube, the oil filler cap or even the charcoal cannister.

Sometimes, we find it necessary to inform customers that the only alternative to keeping the oil transfer out of the induction system is : direct the breather hose to a suitable catch tank, then direct a hose to the lower extremities of the vehicle. Directing the hose in this manner removes the offensive “blow-by” smell. "
===============================
To sum it up, the normal vent air flow path is from the carbon can through a hose & restrictor hole to the valve cover, through the engine, out the front side plate, through a hose to the carb or carbs, suction. The restrictor hole should be from 1/16" to 1/8" diameter. No pcv is needed. Under very heavy load-blowby conditions where this normal ventilation is not adequate, part of the blowby reverses direction & goes out through the restricted vent & out into the canister.

You need a hose fitting on the cover with 1/16" internal restrictor going to the carbon can & a sealed filler cap.
D

 

[Bret]

UP Date!

Ok things are working out now. I managed to get a good tight seal using some a PVC Grommet from Mr. Gasket (#6377) along with some Permatex 1 Form a Gasket Sealant. This is only a temporary set-up until I can come up with something better. Using a new valve cover gasket I went ahead and installed it and I must say it looks pretty clean - check it out.

Alloy Valve cover W/new breather.

Breather hose connections:

Again I gutted the valve components out of a common PVC valve and put in a restrictor with 0.125” hole. While it doesn’t show it in the picture I sealed the vented oil filler using self-tapping sheet metal screw along with some gasket sealant.

A surprising positive side affect: I must have been leaking (blow by) for quite sometime now. Before all of this once the engine had been running at temp for awhile my oil pressure at idle would drop well below 50psi and hover between 30 and 40Psi. Now at idle is stays at a healthy 55 to 60psi.

[ 03-14-2004: Message edited by: Bret ]</p>

 

[nedley]

Bret -

Much to do about nothing I believe. In B's with crankcase ventilation systems, the valve cover was vented into the charcoal canister for environmentally friendly reasons. The oil filler cap was NOT vented. If you've ever noticed the vent size on an original vented-valve cover, while the vent tube is rather large (adds stability I suspect), the actual vent hole in the end of the tube is very small. Now, the aluminum MG valve cover you show in the picture has a vented oil filler cap, thus negating the need for another vent. I know...I have the same setup. I replaced my vented valve cover (which vented to the engine compartment as my B was desmogged before I ever got her) with one just like yours (with the vented oil filler cap). It's worked wonderful. No issues what-so-ever.

Just my $.02 worth!

 

[Sharibopper1]

Thank guys, hopefully you, may have helped me solve my problem on my MG Midgett ( 1979 ) I just had the engine rebuilt, and a previous owner had removed the emmision control system, and put a webber carb. on, am still having problem with the oil preasurer. What I got from your chat, sound like what I'm dealing with.
Thanks Sharibopper1