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MG MGB Technical - Valve cover breather vent

I'm rebuilding the engine on my '69B Roadster. I had earlier posted the below query on the MG Experience BBS with no replies, so maybe I'll have better luck here:

As I am retaining my "original" valve cover with the vent tube positioned on the top of the cover, at the rear with the 90 degreee turn toward the left as one is viewing the engine from the front (the vent tube with the 3/32 inch opening)...I need to consider a filtration system to allow clean air to enter the valve cover. Using OE non-vented oil filler cap.

I am not going to mount a charcoal canister, so I'm considering one of the K&N vent filters, which I assume is intended primarily for the crankcase breather. I see no reason why the filter cannot be used for intake as well as output.

Does anyone have experience they would like to share concerning some of the examples I've posted below, or other alternatives?

http://www.aptfast.com/

Vent Filters, Cleaners & Misc

62-1330 Vent Filter 1/2" ID Flange, 2"OD X 1-1/2"H, Chrome Top

62-1170 Vent Filter 1" Vent Tube, 3"OD X 2"H, Chrome Top

85-1120 Adapter,90 Plastic Elbow Fits 1/2" Hose, Requires 9/16" Hose

85-1140 Adapter, 90 Plastic Elbow Fits 3/8" Hose, Uses Grommet
g. kinslow

It is hard to tell for sure, but the two photographs on page 63 of Clausager's "Original MGB" show a vented filler cap and no elbow fitting. The lower photo, taken of the right side of the engine, from above, clearly demonstrate no elbow fitting.

The valve cover, with elbow fitting and restrictor was introduced when there was first a requirment to fit a charcoal cannister and is not correct for your car.

Therefore, you have two options. First is to find and fit the correct valve cover. Bob Schaulin at gbmg@aol.com probably has the correct cover in stock and his prices have always been reasonable. This would be the way to go if you are building a show car or a driving car that will also be entered in shows.

The second option, as you have already noted, is to fit some form of filtering device to the elbow. A short piece of hose of the proper size and some form of filter to plug into it would be all that would be needed. This would be fine if you just want a driving car. I would probably want to secure the filter to some part of the engine, heater, or engine compartment rather than let it dangle at the end of a hose, but it should not be a signficant problem to design some form of bracket to hold the filter steady. Les
Les Bengtson

I have used small filters for vents in applications other than MG and they work fine. Go to Advance, Autozone, Checkers or Pep Boys to name a few and you should br able to find a small filter that will slip on the existing vent tube. You don't need a big filter because of the small vent hole. Use a nylon tie or a small hose clamp to secure it and you're all set.

Clifton
Clifton Gordon

Is there a reson to not reinstall the charcoal canister other than to declutter the engine bay? It doesn't affect the cars performance and is easy to rebuild.
John

'69 wouldn't have had one originally.... But I agree - for cars that have them, there's no reason to remove them.

Gary, I would imagine that the filter might work, but I'd think the better solution would be to get a valve cover without the breather tube and hook everything up as per '69 specs (vented oil filler cap, etc.) I can take pictures of mine and answer any specific questions re: '69 plumbing if you need...

HTH!
Rob Edwards

Actually, I have been looking for a correct OE valve cover but one in good condition is hard to find. My mechanic recommended a new ribbed logo alloy cover as a suitable top for a complete rebuild, but I would rather keep the factory cover. To be honest, I'm not a great fan of the OE vented oil filler cap. I've seen too many instances of others' caps getting clogged up with condensation and emulsified oil, or even spitting or emulating a runny nose. Not a pretty sight.

And, here's the strange thing: None of the "vented" aftermarket alloy covers have the 3/32 opening, so I really wonder if such a tiny aperture is necessary anyway! If not, it's a simple matter to just cut the tube below the elbow and stick a filter on it. Much more straightforward and then I'll have a mini filter with a chrome K&N logo filter cover!

Rob, thx for the offer, but I'm running a Weber, so the crankcase plumbing won't be identical anyway. At present, I have the crankcase breather/flame trap venting through the Moss metal tube extension down along the side of the block to the street. I cut the end at an angle so the forward motion of the car creates a venturi effect, sucking out the fumes.

After I rebuild my dual HS4 setup and polish the carbs and linkage to a brilliant shine with a pair of K&N chrome-plated air filters, I'll reinstall thwm and return the crankcase breather plumbing to the '69 model specs.
g. kinslow

Sounds like a plan. Re the oil filler cap getting plugged -- that shouldn't be a problem if replaced following the recommended service interval (12,000 miles/12 months). If it does, then there's a problem somewhere. ;-)

Cheers!
Rob Edwards

G. Bob Schaulin will have the proper valve cover and at a good price.

John. The addition of the charcoal cannister, where one did not originally exist, would require some modifications to the mounting point. The original purpose of the charcoal cannister was as a vent to the fuel tank, which was no longer vented to the atmosphere. Hence, the purpose was two fold. First, any gas vapors were supposed to be vented into the charcoal cannister and, if there was any fluid build up, or excessive vapors, the intake from the valve cover was supposed to bring them into the engine where they would, eventually, be burned. The charcoal cannister also had an "open air vent" to the atmosphere through a hose running through the engine compartment to the front of the radiator valance. Thus, the proper installation of a charcoal cannister would be a rather complex solution to the very simple problem of not having the correct valve cover. It could be done, but there are, in this specific case, no real benefits to be derived from such work. On the other hand, I do not believe that any car that originally had a charcoal cannister should have said cannister removed. Both my daughter's 77 and my 79 were originally equipped with the charcoal cannister as part of the original pollution control system and both still have them because it makes good sense. However, in the case of "G", this would not make good sense. Les
Les Bengtson

I have been using this one for years:

http://www.aptfast.com/Images_Parts/kn/Filters_Components/62-1330.jpg

Works fine.
Richard Smith

Les, my apologies, I didn't realize the 69 didn't have a cannister originally. I thought Mr. Kinslow was going to remove an existing one.
John

Re.

http://www.aptfast.com/Images_Parts/kn/Filters_Components/62-1330.jpg

That's exactly the unit I'm considering.
g. kinslow

John. No need for apologies. We are all here to learn and to share what we know so that others may learn from us. The charcoal cannister came in with the non-vented gas tank filler caps as a method of containing gas fumes, its main function, along with venting the overflow pipes from the carbs. An excellent idea and I would never remove a charcoal canister from an existing system, nor would I recommend anyone else do so. Les
Les Bengtson

I also am running the 62-1330. It works great. No complaints.
Jeff Schlemmer

This thread was discussed between 10/04/2005 and 11/04/2005

MG MGB Technical index

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