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MG TD TF 1500 - Carb overflow tube routing

When I got my overflow tubes from Moss (PO had cut old ones off), I never figured out how to route them properly; I ended up just running them both straight down and then giving each a right angle turn. But today, I wondered what the "right way" was.
Luckily, I thought before I started a thread on the subject, I'd search the archives.

OUCH!!!!

Looks like there's entire volumes devoted on the right way to route these tubes!

Forget I asked :)
Geoffrey M Baker

Geoff,

The factory deliberately routed the overflow pipes away from any possible hot exhaust. In the case of the TD and the TF, they are routed FORWARD and through an oblong hole near the bottom of the engine plate, so that they exit on the front side of the plate, and are secured there, with a clip.

I'm not convinced that that is the safest, and have routed mine pointing backwards and as far away from the exhaust manifold, as possible.

In doing this, I made sure that the pipes wouldn't squirt raw gas directly onto the actual exhaust pipe.

I'm sure everyone will have their own way to plumb this.

Gord Clark
Rockburn, Qué.
Gordon A Clark

Geoff, see http://www.ttalk.info/td_pipes.htm for some ideas opn the subject. Bud
Bud Krueger

Thanks for the link Bud! Very helpful
Geoffrey M Baker

Buds pictures are pretty correct until the clip. Its actually attached to one of the water pump bolts.

As Gordon states you can either stick them through the hole (not sure why and its a pain to do but I have seen SOME cars that have it this way originally) or you can just have them bend over the edge of the engine bearer plate and both go straight down (this is also an acceptable factory routing).

Either way they get stuck through the clip that Bud shows and trimmed off just a little below the clip.
Christopher Couper

The images came from Ed Kaler of JustBrits. Bud
Bud Krueger

There has been debate on the routing through the hole..I cannot see an assembly line operation fiddling around running the pipes through the little hole. In the archives there is a definitive image of an untouched car..the pipes do not go through the hole. Over the top of the plate and through the clip. Regards, Tom
tm peterson

I agree with Tom. Cheers
Peter TD 5801
P Hehir

Mine go thru the hole. Then the brass clip. 51 TD.
Brian W.
ZBMan

brian, probably not worth the effort to make it factory correct. just leave it in the hole. regards, tom
tm peterson

A few months ago Frank Cronin posted pics of a virgin TF. Here is a closeup of that pipe routing. Looks like they go through the "hole" and then looks like a pipe, perhaps rubber, is stuck on the ends.

Tom
'54 TF

T Norby

Tom, pics in the archive show an untouched TD with the pipes over the top. Really cannot imagine a production operation, where time is money, paying a worker to fiddle around running the pipes through the hole..no justification for the extra time on the production line. Regards, Tom
tm peterson

Thanks for posting this thread I have mine on the back side of the engine load plate which is obviously wrong..
CJ Henderson

Studying the carb overflow pipe debate and seeing both methods on untouched cars -- thru the hole and over the plate -- I went over the plate using the same simple logic Tom mentioned.

As for the rubber hoses on 9052, the owner stated these were original if I recall correctly. There is also a hose attached to the drain tap to the radiator on the car. There is a period drawing / photo somewhere showing a hose attached to the drain tap to the radiator but I can't recall exactly where. WSM? Factory drawing? Sorry, my memory is blank right now. I think Rob Grantham saw such a pic. Maybe he can chime in.
Frank Cronin

Two comments:
First, I can appreciate securing the tube(s) with some form of clamp. We had a nice, new straight tube that came with the supercharger, and I made a few smooth bends via tubing bender. Looked really nice while it lasted. Now there's just the cast banjo fitting with a copper stub sticking out. The copper tube broke off and disappeared.

Second comment is there an obvious reason why the tubes run down past the exhaust under the car, and that's in case the needle sticks open. There's another not so obvious threat and that is the release of gas vapors, starting with the most volatile compoents in the fuel which evaporate easily, and lots of them when the engine shuts off and exhaust heat rises up to the carbs. Under extreme conditions, the entire contents of the floats and fuel lines from the pump can boil dry, (I know, there are those that don't believe in vapor lock) and that can constitute a significant volume a gasoline vapor.
JRN JIM

The Workshop Manual in Section D (Illustrations D1 and D2) show the carb overflow lines going over the front plate (D1) and the drain pipe fitted to the radiator drain tap(D2). This is a metal pipe that secures to the drain tap via a threaded nut. I have seen this on 2 TDs - I imagine many of the drain taps have been changed over the years - I don't think the proper type is supplied by Moss or Abingdon.
DLD

I got a correct rad drain tap and beautiful drain pipe from Abingdon when I restored my TD around 2006, so they had them then. No clue if still available now or not. I think the TF tap was different, with no threaded on copper drain pipe. Carb pipes? Who knows, over the plate makes more sense. There is a factory picture out there somewhere of a TF motor/tranny that clearly shows the pipes going through the hole, I will try to find it later. Back years ago, the few T-series cars in town including my own had the overflows either missing/broken off or about 6" long. Never had any fires that I recall. George
George Butz

Page 46 of the Driver's Handbook (AKD 618E) also has two illustrations. The top sketch clearly shows the radiator pipe & the other has the fuel overflow pipes going over the top of the plate. Both the WSM & the Driver's Handbook are in agreement. That's good enough for me. Cheers
Peter TD 5801
P Hehir

Couldn't find the factory shot, but found this: Unrestored TF from Chris Couper's TF site, clearly through the hole. Seems TD's may have been over, TF's through the hole? George

George Butz

My TF and Jim Hokcombs unrestored TF both had them thru the hole and clamped on the front. This gives a steeper slant to the tubes and increases the possible flow rate
Don Harmer

I don't have a pic, but I also put the ends of the overflow pipes in a rubber tube to stop vibration,,,
I routed mine over the top of the plate to make it easier to remove/replace them during carbie work, and then through a 3 inch length of rubber tubing which I "Spiral Cut" from one end to the other. The spiral cut allows the rubber tubing to wrap around the two OF Pipes and fit tightly around them,,

SPW
Steve Wincze

This conversation assumes the overflow pipes actually carry away unwanted fuel. There are two important assumptions here:

- The overflow pipes are not accidentally blocked (with crud or whatever)

- The tickler pins on the top of the fuel bowl are sealed.

A posting from 14 Nov 2005:

The overflow pipes will only work if the tickler pins in the fuel bowl lid have been sealed. The tickler pins are lower than the height of the overflow pipes and will allow gas to spill out the top of the fuel bowl lid if the fuel bowl overfills.

I have heard the problem described as a design error that was rectified in later lids, where the hole is sealed. I corrected the problem on my TD by cutting the tickler pins shorter and bedding them in epoxy putty in the fuel bowl lid. They look proper but fuel can't leak around the pins.

Larry
Larry Shoer

Larry: I wonder if O rings would solve the problem while allowing the pins to still tickle the floats.
Christopher Couper

Chris,

I suppose, in theory, yes. I'm not sure how to secure the O-ring in place so the pin moves up and down and the seal is maintained. Also, the friction between the pin and the O-ring could keep the pin pressed into the bowl, so that the pump runs continuously.

Recall that the factory decided that the tickler pins were of marginal utility so simply removed the tickler pin and plugged this hole in the fuel bowl lid in later models.

Larry
Larry Shoer

Does anyone have any documentation showing the factory really had such negative thoughts about the tickler pins? Or, was it just a ££ issue? Bud
Bud Krueger

Bud: I think you are confusing MG with GM :-)
Christopher Couper

No, Chris, I'm just having a lot of difficulty separating the 'factory decision' from an urban myth. Bud
Bud Krueger

Some years ago, the available tickler pins had a nifty flat washer with some type of flexible sealing washer above it, so the spring pressure would seal the opening. For many years, I had floats stick open, usually on start-up, and used the pins to flush out. So they really did work. George
George Butz

Bud,

While one may debate the factory's motivation for discontinuing the overflow pipes, it is true that fuel rising in the bowl will reach the tickler pin before it reaches the overflow pipe.

George's comment about a washer system that seals the tickler pin is interesting. Barring such a system, the ability of fuel to leak out the tickler pin is a preventable safety risk that I consider desirable to address.

Larry
Larry Shoer

George,

If the float on your TD was sticking open, am I to understand you to mean that the needle valve was sticking open? If so, an incomplete seal or more likely non-existent seal on the tickler pin is exactly the problem my posting is concerned about!

Larry
Larry Shoer

Larry, back years ago (starting in the 70's), the TD's tank had a lot of rust and gunk in it. For many years, one of the original type needles would get gunk in it, often at start-up and the pump would click away and run gas all over the place. Pushing the pin would clear the debris, etc. Probably lucky it never caught on fire. Eventually, cleaning the tank, an inline filter, and grosse jets cured that. It was maybe 15 years ago that the supplied silver/gray color tickler pins were supplied with the sealing washer. At restoration, I used the now available brass pins and epoxied sealed the pins/holes. George
George Butz

Right then you lot:

As ever, I'm rather late in dropping my thrupnee bit but here goes.

The overflow pipes, routing saga: The Works plan for the aft pipe, being passed alongside the full length of the block, above the exhaust pipe, always seemed a bit "iffy" to me. But then who am I, eh ?

Furthermore; to bend them both, forward, through a hole in the engine bearer plate also seemed weird, well, to me to at least.

Now. as I am not in the least interested in "concours d'élégance" battles I do not worry about the way the pipes leave the tops of the float chambers. My only concern is that they lead away from the block and other heat massing areas as well as possible.

Therefore; I have routed them as follows:

The aft pipe; drops straight downwards, secured by a clamp, using the outward starting motor bolt hole (I have a three bolt flange starting motor as per a TC). The outer hole is vacant when using a two holed TD motor. The lower end of the pipe, when found to be well clear of the sump, is bent outwards or to the right, towards the frame.

Similarly; the forward pipe, drops downwards, clamp secured to the aft side of the engine bearer plate and the tip bent outwards, towards the frame, as per the aft pipe.

However; somewhere in all of the above submissions, I reckon I missed where and how the "tickler pin" relationship, to the overflow pipe, was introduced. ?

I also read that the tickler pins, being situated below the over flow pipes, may be a cause of possible petrol leakage. I have them in place on both the TC and TD carburetter assemblies. They mounted through the tops of the float chamber lids and as of yet, I have had no problems with leakage. (Just lucky I suspect)

I have seen carburetter set ups, on other British makes, with tickler pins placed near the bottoms of the float chambers. I wonder what problems, if any, that positioning may create with leakage ?

I know, enough written; awaiting the return barrage:

Emdall, TC6768/TD3191. Halfmoon Bay, British Columbia, Canada


Jack Emdall

This thread was discussed between 14/06/2014 and 19/06/2014

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