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MG MGA - overflow pipe

a time ago i saw a picture of the route for the overflow pipes from the carburettors i think it was a pdf file but i not sure .it showed an A serries engine with the pipes. does anybody have this picture ??

http://users.pandora.be/mga_world/

serge

Check your E-mail
Hope this helped
Jones

Mr. Jones
Any possability of a copy also. coupe@total.net
Thank you Gordon
Gordon Harrison

Better yet - why not email to Barney Gaylord so he can post it on his site - www.mgaguru.com
Tom Dimock

Jones, I'd also be interested in obtaining the picture. Thanks
Steve Jackson

Could you add me to the list of people for this diagram please
Shane Rossetto

Okay, I'll bite.

C.Jones, If you know the original routing for these pipes, please send it my way, and I will post it on MGAguru.com. I have my own ideas about least inconvenient routing, but original would be nice to know.
Barney Gaylord

Well that was quick. Apparently I got the same picture (without heat shield) from C. Jones and from Peter van Kester. I also find a picture with heat shield in the factory Workshop Manusl, which is closer to the truth but still not perfect. Find these pictures and my personal notes here: http://mgaguru.com/mgtech/carbs/cb109.htm
Barney Gaylord

Barney

I have not seen these pictures before. Slightly off topic but I was quite interested with the lower picture that shows the flame trap for the vacuum advance sited higher up than discussed in a thread earlier in the year. At the time the concensus was that it was attached to one of the rear manifold studs. Unless my eyes are deceiving me with the shading this picture appears to show it level with the intake manifold.

Steve
Steve Gyles

OK Barney your name in my book will be Lighting. That was quick.

By the way I saw a Roadster with rocker panel covers as in my coupe.but no weather seal retainers.

Cliff
Jones

One thing puzzles me about the SU overflow pipes as shown in the Workshop Manual picture on Barney's website.
Why do the two pipes finish at a different height? I would have thought that there would be an optimum point for them to finish and they would both use that point.
What is the optimum point? Not too short so that expelled fuel would be carried to the exhaust downpipe. Not too long, below the base of the oil pan where the high air velocity would cause a suction in the pipes, as this would act like an anti-run on system by applying suction in the SU fuel bowls.
I believe that just below the engine block to oil pan joint would be perfect.
This is where they both finish on the mga twin cam engine (even though the SU's and the exhaust pipe are on opposite sides of the engine).

Mick
Mick Anderson

Mick

I think you will find they are identical length. It's just the the rear one has further to run to the common bracket.

Steve
Steve Gyles

Steve

I guess you missed the fact (earlier in the year) that the flame trap was mounted on the manifold stud between rear carbie and rear manifold branch. I recall the pic of your own engine showed it in the wrong place as was mine...

Pete
Pete Tipping

Steve,

The point I was trying to make is that they should be different lengths. I believe that they should finish at the same point.

Mick
Mick Anderson

Sorry Mick, I misunderstood you. I guess in those days SU just produced one standard length. I suppose MG could have chopped them off to the same length for neatness.

Pete

No, the point I was making is that the flame tube appears to be set up high, about where I have my 'incorrectly sited' flame trap. The concensus earlier this year was that it should be located lower down where you described - by the manifold studs.

Steve
Steve Gyles

i had a look at my overflow pipes these are still on the shelf. i brougt them last year at silverstone from some MG club stand. i saw there was no hole on both pipes from the banjo to the pipe so i can't blow air trough the pipes so are these ment only for decoration or how do they suppose to work ???

http://users.pandora.be/mga_world/


serge

For length of the pipes, form follows function. Both are the same length to avoid the need to stock and handle two different part numbers and redundant inventory. The rear pipe has farther to run to get to the "P" clip, finishing shorter on the bottom end. As long as the difference in bottom end height does not affect function, it is less expensive in production not to trim them. For conxours they should be as pictured.

When you buy replacement parts these pipes may be longer than original, being made as one part number for various applications. For my common sense, I would like them both to terminate at bottom the sump flange. I don't like the idea of fuel spattering off the top of the sump flange to make a mist on the exhaust pipe. Otherwise I would trim the lower one to match the height of the higher one just to be neat, and maybe avoid damage in handling.

The fuel trap on the vacuum pipe is shown in the correct position. The bracket attaches to the rear most manifold stud as the pipe will skirt around the rear edge of the heat shield to the bottom of the fuel trap. The trap stands vertical so any trapped fuel will fun down by gravity to be drawn back into the venturi, and the top end tube runs to the distributor. The bracket is about two inches tall, clamping to the center of the fuel trap. In the picture you can see the top bend on tube just above the rear dashpot but well below the top of the vavle cover. Any appearance of excess height may be an illusion due to the elevation angle of the picture.

Yes Serge, the fuel vent pipes must have a hole so you can blow through them. Your new ones must be defective, possibly clogged with excess solder at the pipe to banjo joint. These parts are tricky to solder by hand as it is easy to apply excess heat and melt the brass and copper parts. If you want to try to repaie these parts I suggest apply low pressure compressed air to the pipe and, then heat the banjo solder end gradually until the solder melts and is blown out by the air pressure. Wear long sleeves and gloves and goggles when doing this to avoid personal injury by possible flying molten solder.
Barney Gaylord

Barney

I repaired the overflow pipes,but it was impossible the way you discribe it.It looked that there was no hole in the banjo at all.so i drilled a hole from 2mm from the banjo to the pipe. i saw your first picture about the overflow pipes (the one without the heatshield) i think it isn't possible to put the pipes like this when the heatshield is installed.to do it this way the second pipe should go on top over the heatshield,because the heatshield comes on the bottom halfway the exhaust manifold.


http://users.pandora.be/mga_world/
serge

This thread was discussed between 27/07/2006 and 02/08/2006

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