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MG MGA - vapour trap

Hi all, in the middle of the vacuum pipe that goes between the carbs and the distributor, is a vapour trap,which is held in a small bracket.Can anyone let me know exactly where this bracket is supposed to be bolted on to?.
Regards,
Steve Ash.
S Ash

Hi Steve on my roadster it was bolted to the exhaust stud nearest the bulkhead in a little bracket as per the photo


regards gordon


g c pugh

It goes on the next to last exhaust manifold stud (see photo). Even with the engine out of the car I found the vacuum pipe to be a real SOB to fit. It is 1/8" steel tube which makes it difficult to bend and fit correctly fron carb to dist.

I even bought 3 ft. of 1/8" COPPER tube with the idea of brazing that in place of the steel. After a couple hours of struggle and many four letter words I managed to get the steel tube to fit. I still have the copper as a backup.



H Speer

Every one I have encountered has it where Gordons photo has it - on the last exhaust stud. With the bracket 'up' and the capsule fitted above.
Barry
BM Gannon

Aside from being original, does the vapor trap really do anything useful? Mine was replaced by a rubber hose years ago and nothing seems to have suffered. I don't recall having such a trap on any other car I've owned.

Ken
k v morton

If we take Clausiger as gospel then it goes on the next to the end exhaust stud. However having struggled to fit mine on there I can well understand why most people say "Oh what the ..." and put it on the end stud which is much easier to do.
David
D C GRAHAME

Steve, I believe it originally went on the next but last manifold stud per Henry's photo, although it's far harder to install there unless you put it on before you install the heat shield. I also think it's more of a vacuum anti surging device rather than a vapour trap. It prevents instant changes in vacuum at the distributor by acting like a vacuum holding/storage chamber.

Andy
Andy Preston

Actually, it is a vapour trap. It is filled with metal wool, similar to steel wool. Its function is to prevent fuel accumulating in the vacuum line and reaching the diaphram of the dist vaccum advance. Raw fuel could do damage to the diaphram.
H Speer

I understand the intended purpose of the vapor trap; I just have never seen one on any other car, and wonder if it really functions as intended, and if it is really necessary. Is the MG diaphram more prone to trouble than one on, say, a Triumph, or Volvo, or Jeep? I have been without one for years on my MGA, though I haven't covered a lot of miles recently.

Ken
k v morton

This thread was discussed between 15/02/2009 and 16/02/2009

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