Advance - retard question

[Hicks51]

Although it runs well, my TR3 (circa TS16764) is a bit of patchwork quilt under the bonnet, with components from various years, and I'm having difficulty establishing where the end of the advance-retard tube should terminate. Currently the copper tube has a threaded brass cap that screws onto a fitting that is tapped into the far left (battery) side of the high-port inlet manifold. The tube has an olive on the end but it doesn't feel as though it's being compressed when I tighten the fitting and the pipe wobbles about, so I assume it's letting in air.

 

I have no idea what the engine number is, as the numbers cannot be read, so I don't know if it's original to the car.

 

I've tried studying photos of other cars, but cannot see where and how the advance-retard pipe should terminate.

 

Can someone help?

 

Thanks, Brian

[vic]

A photo might help identify what you've got and possibly where it should go.

My 3, running a low port head and H6 carbs sees the tube attached to a fitting tapped into the underside of the throttle housing nearest the radiator.

If the nut is too long, you could attempt to shorten it. Or take up the excess with suitable brass washers (the sort found in electrical components), and a little ptfe tape.

Does the nut display signs of a split or fracture along its length? If so replace

Is the thread on both components complete and undamaged? If not replace

If the olive is shot replace it.

My choice would be to replace the tube complete with matched fittings.

Vic

[ians]

My TR3 set up is the same as Vics. The vaccum tube is screwed onto a boss (part number AUC5100) which is fitted into the underside of the front HS6 carb which I believe is correct for the 3. See page 40 in the Moss catalogue which you can download from their website. Might help you identify what you have got!

[Hicks51]

_{Thanks Vic and Ian,}

 

_{Your replies have confirmed my suspicion that the car is even more hybrid than I first thought!}

_{This is compounded by having a later distributor (rebuilt by Martin the DD), with a rubber connection to the vacuum unit.}

 

_{I'm sure I'll be able to make it air-tight somehow.}

 

_{Thanks again,}

_Brian.

[Richardtr3a]

After reading this topic I went to the car and my tube is similsr to Vic's fitting but is moving up and down freely as if the tube nut was not long enough. I think that I may go for renewal. Do Moss, or anyone, carry stock in copper?

 

I do not want to move my float chambers, and I can only just see the fitting. Can you tell me which spanner will fit the very small nut?

 

Thanks, richard

[vic]

Hi Richard

All the major Tr suppliers - Moss/Rimmer/trShop- will supply what you need in brass.

The nut size is - 3/8ths.

Regards

Vic

[Rodbr]

Check Fleabay Item number: 160816593529

This what you need complete with the olives.

[Richardtr3a]

I tried tonight to fit the new pipe nut to the underside of the front carb but it is very hard to get the spanner to fit without dismantling anything. It would not tighten up even after a lot of twisting. It looks as if it is almost fully home but there is still movement. I am frightened that the front carb has a stripped thread.

 

How could it be repaired? Is there some way of glueing with Loctite or pfte tape? I have not got time to take it off and send it away somewhere before le Mans.

 

What do you advise?

[Rodbr]

Hi Richard,

1. At the risk of stating the obvious you are using the correct hole and not the adjacent one that the PO has managed to force the nut into.

2 Have you managed to crimp the olive onto the pipe? If not try the following:

Note if you have check how far the olive is from the end of the pipe as it should be about 1/4 an inch ish from the pipe end and if not the pipe was not in far enough before attempting to tighten.

 

Use some Vasaline and coat the threads, screw it in as far as it will go easily and then progressively wind it in and out a flat at a time till you are sure it is in as far as it will go.

Remove it.

Push the pipe through and fit the olive about half an inch from the pipe end.

3 Insert it into the orifice on the carb as far as it will go, (should enter the carb body at the bottom of the hole)

You need to make sure that the pipe is in far enough so that the compression of the olive reacts against the bottom taper of the hole and compresses onto the pipe.

Then tighten up the nut and hopefully the final nip should compress the olive, DO not grunch it up tight and overcompress the olive as it may not seal.

 

If you still find it to have a little slack remove it and put 2 or 3 turns of PTFE plumbers tape between the nut and the olive and try step 3 again. (do not overkill on the tape "just in case"!)

You can always add some more.

Hopefully it will nip tight this time.

 

Have just fitted this myself with the kit I suggested to you above and found that the brass carb nut was quite coursely cut and was tight to get into the threads and get it tight initially.

 

The above procedure worked for me (without the plumbers tape) so good luck.

 

Sorry if this sounds a bit pedantic but it is difficult to advise without seeing what you either have done or or has been done.

Rgds

Rod

Edited June 15, 2012 by Rodbr

[vic]

I agree with Rod, but don't forget that ptfe is intended to seal around the thread it will not cure the problem you describe.

In terms of access, have you removed the air filters to provide improve it and give better sight of what you are trying to do?

I don't seem to experience too much difficulty getting to this joint by doing so.

It is beginning to sound like you have a real 'Heath Robinson' solution and the only cure is to bite the bullet, remove the front carb and do the job once and for all as it should and was intended to be done. Can't help but think that it was in the wrong position in the first place because it was trying to be fitted to a damaged component.

A couple of hours work and all will be well I'm sure.

Regards

Vic

[BrianC]

Rod's advice is spot-on. Having experienced a similar problem recently when the vacuum pipe came loose because the olive wasn't fully compressed (although it had been fine for 15000 miles). I found the key to getting it to stay in place and leak-free was to ensure that the pipe is pushed up as far as possible and held in place whilst you tighten the nut which will in turn push the olive up to its rightful place and eventually seal and tighten onto the pipe. A mirror and good lead-light or torch are essential to avoid fitting to the wrong place, cross-threading, etc. Without them, I wasted an awful amount of time trying to do it blind. Finally I managed it quite easily without removing air filters or anything else, but finding a suitable short spanner that fitted the flats was the hard part!

[Richardtr3a]

My carb did not have the fitting threaded into it and the tube has the wrong end. I am starting again tomorrow after the tennis.

 

Richard

[Richardtr3a]

This job is now complete. It took me a long 4 hours and I was advised to rmove the carb and fit AUC5100 on the bench. This is the brass boss with a seating for the olive which is missing from the tapped outlet in the carburettor This was very good advice. My car had been tuned several times by carb experts over at least 20 years it was never noticed that the olive had no shoulder to sit against and that the pipe nut would therefore never be tight.

Once free from the manifold it became clear that the brass adaptor will only grip by about 3 threads and is quite delicate. I wound the pipe nut on to it a few times with one end in the vice and the threads are very poorly cut and need some force to move. Once it would wind on by hand I offered up the copper pipe and olive and managed to get a good fixing. However the copper pipe would not slide into the adaptor as it was very marginally too big. I had to use a bit of sandpaper and smooth it down This would all be impossible on the car as the copper pipe has to be absolutely straight and you can not see well. The parts just do not fit together well.

Then I fed the pipe into position and fixed the carb back on.

Finally it took 1/2 hour to make the connection at the distributor end using the same nut that came off earlier. These threaded fittings are not good quality but with gentle perseverance can work.

This means that I will have a working adv/ret for the first time in years as long as the distributor end is working. It is about 3 years old from the Distributor Doctor so is probably working OK.

Now I need a rolling road for a test. Is there anyone near me in SW London ? Thanks very much for the help on the forum without which this would never have been repaired. It is a great facility.Also it leads me to wonder what other mistakes may be hiding on my car.

 

thanks

[jean]

Big mistake on my TR3A... I,m driving now for over 12 years without the retard system and a 25D4 dizzy and this without any adverse effects. But I'm not an originality fan..

[Ashley James]

The vacuum advance works on the overrun a under light throttle, more as an aid to fuel economy than anything, so it makes sense to have it working correctly IMO.

 

http://en.wikipedia.org/wiki/Ignition_timing

Edited July 3, 2012 by Ashley James

[Richardtr3a]

I am off to CLM on thursday so we will see if there is any improvement in mpg.

 

Thanks for all the help.