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MG TD TF 1500 - Carb Jet Seals

When I bought my car, the carbs worked well and didn't leak, but seeing that they were dirty I decided to rebuild them and in doing so I replaced the jet seals with the improved Moss seals. The O ring type seals I got from Moss didn't leak, but they gripped the shafts, which were highly polished, and made them hard to move, never returning to the idle position without forcing them by hand, this was no good. With suggestions from others I ordered the Teflon seals and installed them. The Teflon seals leaked like a sieve and nothing I could do would stop them from leaking. So because the old cork seals didn't leak and I have no idea how long they were in the carbs I bought new cork seals, soaked them in oil for 24 hrs and installed them. the jets now work very easy, returning to the idle position by them selves and do not leak a drop! So I guess SU knew what they were doing when the initially used cork. Lord only knows how many years the car ran with the original seals in the carbs and now it's going to have the cork seals back again. To me sometimes a new product is not the best idea. If they work for others I'm glad, but I'll stick with the old design, it seems to work very well. PJ
Paul S Jennings

Paul, I contemplated buying Burlen's "no Leak" seals but didn't want to wait for them and the ridiculous shipping. i'm thinking you saved me from a disappointing change over. My Moss kits just arrived so I will be spending tomorrow going through my H4s, again. Thanks for sharing your experience

Cheers

Bill Chasser jr
TD4834

W. A. Chasser Jr

The jets have to be mirror smooth without any scores for the Teflon to work. Glad corks worked for you. 8 years and counting with my perfect Teflon! George
George Butz

Does Moss sell the Teflons? I didn't see them when I ordered gaskets and seals.

Cheers

Bill Chasser jr
TD4834
W. A. Chasser Jr

Paul, I ran into the same thing when I rebuilt the carburetors of 'the53'. Ended up with good old fashioned cork. Bud
Bud Krueger

Since I have been running with the teflon 'O' rings from Tom Bryant for somewhere close to 20 years if not longer and have never had a leak, I have to wonder if the recent problem with the seals is not improper installation. Teflon is extremely fragile and easily gouged. They must have the item they are installed in/on properly prepared. First, the jet needs to be carefully smoothed. They don't really need to be polished, but they do need to be free of any gouges or any other sharp edges, this includes the bottom end of the jet (it needs to have the edge relieved and sanded smooth and rounded so there is no sharp edge that can cut the teflon). The same preparation needs to be applied to the cross drilled hole part way up the jet. This area is even more prone to cause damage to the teflon 'O' ring and must be sanded and the edges must be smoothed so that they don't cut the 'O' ring. I am assuming (particularly if you purchased the 'O' rings from Tom Bryant) that two 'O' rings were installed top and bottom. When done properly, the teflon 'O' rings seal perfectly and last many years. Cheers - Dave
D.W. DuBois

Your correct Dave, I bought the seals from Tom Bryant and they are installed double and your analysis of the hole possibly marking the Teflon seal is probably spot on. But, if the carbs work 100% better with the cork seals and they do, with no modifications, the cork stays in. I'm a little curious how this Teflon thing started in the first place and the rubber O rings Moss sells. I tried both and went back to cork. Trying to improve a product that has worked perfectly as was originally designed seems a little over the top anyway, but if it worked for others I'm glad. Just sayin. PJ
Paul S Jennings

I've converted to Viton O rings with the original brass gland washers and they seem to be leak tight.
Dave H
Dave Hill

Paul, Some years ago (80s?) the only seals available were a coarse, porous, dry, and crumbly cork. They were truly awful! If you could ever get them not to leak when new, they did after a short time. This was pre- internet, etc, and you just had to use what Moss or whoever sent you. I presume this is why the teflons came into play. George
George Butz

I have just installed Tom Bryant's teflon seals and would suggest that Tom include a short instruction sheet (concerning preparation of the jet) - this might help folks prepare things properly.

I eased the various edges after reading comments on this BBS - very helpful.
DLD

This thread was discussed on 14/05/2015

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