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TR2/3/3A Vacuum connection at Carb

Dr_Mike

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I started two reassemble my H6 carbs, and found that, using the the kit from Moss, the vacuum connection at the front carb was stripped and only made a very tenuous connection. I have had several suggestions and thoughts about this, and thought I should look or more experience. My favoured idea at the moment is to glue in the connector from Moss with its compression fitting, and a stub of tubing and then use an end to end compression fitting so I can disconnect the line to the Distributor if the carb has to be removed (which history says is certain to happen!), I could try teflon tape on the "thread" but doubt it would hold for long.

Any thoughts experience will be most welcome!
 
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TR3driver

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Perhaps I'm misunderstanding you. Doesn't the adapter from Moss have bare threads on one end, and a compression fitting on the other? So you could glue the bare end into the carb port, and still remove the tube by undoing the compression nut.
IMO that would be better than having a union in the line. If you do use a union, make sure the line is well supported next to it, so it can't vibrate.
 

mastaphixa

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Randall is right about supporting the union. I installed a union out where I could get to in easily when I removed my front carb. I think most of the damage to the threads and fittings on the bottom side of the front carb is due to the difficulty of getting to it in the first place.
 
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Dr_Mike

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Thank you. The "kit" was just the tube and end fittings, so I was not very clear. And I did not know about the adapter. That is an elegant solution. JBWeld will have to be used as the threads are well and truly stripped. I shall have to acquire a new compression fitting from a parts shop. Hopefully , even in this country, that will not be too hard. I guess that this has not been an uncommon problem!
 

TR3driver

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Only problem I've had (with my earlier setup that used the adapter as original) is that the threads on the adapter are British. Takes a certain amount of dexterity to turn the nut when you can't see it clearly, but not too much. I've only had the adapter off maybe twice in some 40 years; but of course the line has to come off much more often. For a while there, I was pulling it roughly once a month trying to deal with various leaking gaskets.
 

CJD

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Thank you. The "kit" was just the tube and end fittings, so I was not very clear. And I did not know about the adapter. That is an elegant solution. JBWeld will have to be used as the threads are well and truly stripped. I shall have to acquire a new compression fitting from a parts shop. Hopefully , even in this country, that will not be too hard. I guess that this has not been an uncommon problem!

This is one of the few times that JB Weld has my approval. It is a relatively cool location and no significant stress placed on it. The only other option would be to find a Whitworth helicoil!?!
 

TR3driver

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The only other option would be to find a Whitworth helicoil!?!
I've not had occasion to try it yet; but I think it could be done by fabricating the special tap and using an SAE insert. Wouldn't be perfect, but I suspect close enough that it would be at least as strong as the original threads. (A properly installed Helicoil is actually stronger than original threads, because the insert can roll slightly and distribute the load better.)

Another option would be to weld up the hole, redrill & retap.

But I agree, in this case, JB Weld is at least worth a try. It does get pretty hot there (radiant heat from the exhaust manifold) but not, I think, too hot for JB Weld (which is supposed to be good to 500F continuous, 600F intermittent).
 

sp53

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JB is ok, but yes it still glue. I would be concerned you do not plug the hole with the stuff. You could always run a drill bit through there when you are done if that is a concern. If the carb is off, I would probably fiddle around more with the threads and try to strip a sleeve or adapter in there. But after that and I broke it then use the JB. I am not familiar with HS6, so not sure where the port is, but one thing I have learned the vacuum advance on the distributor end can be a big problem if it is not working at the distributor. It seems to hold the timing from moving to freely wether it is hooked up or not.
 

Snowkilts

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I've heard about this fitting, but my carb has a compression nut machined into the body of the carb. No separate fitting required. Do I have something special?
 

CJD

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cM69aAg.jpg


Here is one fitting...a separate brass that screws into the carb throat. My TR2 used this. Some later carbs used just a machined boss cast into the carb side, thus eliminating the brass fitting. It sounds like Doc is working on one with the brass fitting.
 

TR3driver

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I've heard about this fitting, but my carb has a compression nut machined into the body of the carb. No separate fitting required. Do I have something special?
There were two different configurations used on later cars; some of them had a male nut that screwed directly into the carb body. I don't know of a change point, or even if there was a change point; but I have seen both.

According to Revington's web site, it should be from TS12820E; but that doesn't match with what I've seen. TS39781LO; TS42xxxL and TS13986E all had the adapter. But Dad's TR3A was somewhere in the TS50xxx range, and had the male nut without the adapter.
 
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Dr_Mike

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My car is TS60014. GOK if the carbs are original after all these years: they have different coloured damper ends, one black, one gold. It seemed to have had a female thread in the body, with was stripped, and the male fitting from Moss did not engage. Hence the conversation about gluing a male-to-male fitting in the hole, which will then need a female compression fitting. Does this help?
I plan to follow this path. I certainly do not wish to have a stress point hanging in space. Just debating whether to replace the jet sealing washers before I try it out or wait to see if it leaks!
Then it is on to the distributor. Ha!

Thank you all for the thoughts
 

TR3driver

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You posted above that they are HS6, which would not be original. All TR3A (as well as TR3, TR3B and early TR4) used H6 carbs.
 
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Dr_Mike

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Ooops. I am sure you are right: I don't know where I got that misinformation from. It certainly does not help with communication!. Thank you.. I have corrected the entry so others will not be confused
 
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Dr_Mike

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Much Thought. Finally decided to use the fitting that John shows on his TR2 Carb,(available from Moss). It means tapping the hole which should not be a problem. BSF thread. If needed the adapter can be "glued" in.This will avoid a lot of concern about stuff coming loose, and i will be able to disconnect from the adapter ( with a lot of fiddllng) if i need to.
Many Thanks again
 
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Dr_Mike

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closer! But I have been "close" for while. Need to actually check that the vacuum advance is working ( this afternoon ) and then wait for the necessary bits to arrive. (2 weeks?) Can set up the carbs next week, and put new seals around the jets, rather than waiting to see of they leak. Otherwise I think I am ready, and quite anxious!
michael
 
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Dr_Mike

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I tried to reply yesterday but I do not see it!
Dizzy is a mess, full of crud and advance is inoperative. Have lost my mity vac, probably in a sale as I have not used it in 25 years. Will substitute syringe and see if vacuum is intact. then big clean up.

Wet and windy outside; kept awake by the sea even though we are not waterfront: just near enough to hear it

Sunday: Dismantled and cleaned , now moving freely. Found the Mityvac ( no pressure gauge) which moves the diaphragm connector, albeit sluggishly, but does not hold it, so the diaphragm probably has a hole. I shall take it to NAPA in the morning and see if they can check it out. Replacement from Moss is about $100 CAD.
 
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Dr_Mike

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Just to add a challenge, the adapters have been retooled to metric threads on each end, but Moss only sell compression fittings with Imperial threads. More thought being applied.
 
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