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MG MGA - Fitting cork seals for carburetor jets

My understanding is that the traditional way to fit these seals is to soak them in oil for 24 hours prior to fitting - my supplier suggested that I boil them in water for a few minutes to soften them, then coat with Vaseline and fit. I tried this way and seems to work fine, the proof will be if they start to leak later. Has anyone used this method?

Also I found that the jet centring button in my carby tuning kit didn't fit the piston - it was about 0.003-4" larger than the shank on the needle - needed to be emery paper down to fit - anyone else had this issue? (I have had the kit about 6 years but first time I used the button.

Mike Ellsmore

Have you considered switching to the teflon seals as discussed by Barney, here?

In addition to being available from McMaster-Carr, the O-Ring Store also carries them.

You need a total of 8 for two carburetors, since it takes two to replace each cork seal. It's a good idea to buy extras (they come 25 to a package from MCM, or individually from the O-ring store), because it is easy to damage them upon assembly. But you get a set installed without damage, they are supposed to be very long lived. I installed them in my carbs, but the car is still apart, so take the preceding for what it is worth.

Edit to add: I used the jet centering tool from Moss, and while the fit was good, I found that I had to polish the tip to keep it from damaging the teflon seals. It would probably have been okay with the cork seals as-received, however.

D Rawlins

Del, the centring button in my kit only goes into the jet bearing and doesnt extend in enough to damage the seals or o rings. I was thinking of the o rings but elected to go with cork seal as they came in the gasket kit and the old ones have given good service. I will end up getting a pack of MCM o rings to keep as spares
Mike Ellsmore

When running my old TF and MGA 1600mk2, I used to keep a complete set of the cork seals in a little jar filled with oil waiting for the day when I next stripped and rebuilt the carbs, which I used to do about every 2 years. I would then get a new set of seals and stick them in the jar for the next time! Nowadays I have a 1959 MGA 1600 which has a 1950cc MGB engine, complete with the MGB carbs (without cork seals) - haven't needed to rebuild them yet .... AB
A Bennett

I am wondering why anybody needs a jet centering tool when its not needed. With the dash pot and needle fitted you simply offer up and loosely fit the whole bottom jet assembly (minus the mixture adjuster nut and spring) with the jet pushed up as high as it will go. Then as you tighten up the assembly the jet will centre on the needle higher up than normal at what is a larger needle diameter. Draw the needle out and refit with the adjuster nut and spring. The jet will be in a lower position and must be clear of the needle.
Soaking the cork seals in oil overnight works perfectly but will leak where ethanol is present in the fuel. Barney's PTFE O-rings will certainly be ethanol resistant and I found the equivalent to his US ones is our UK standard BS10 size.

The issue I have with your method that requires removing the mixture adjuster nut and spring, means after you have centred the jet you then need to remove it completely to refit the mixture adjuster nut and spring. With new soft cork seals these will collapse inwards when unsupported by the jet tube due to the pressure from the internal jet gland spring. While you might get away with removing and refitting the jet tube if the cork seals are old and hard you are likely to damage new cork seals. I reckon it would be impossible to refit the jet tube if O rings have been used.
I reckon this is why the centring button and more expensive Moss alignment tool have been developed.
Mike Ellsmore

I replaced my carb jet seals with the standard cork items (AUC2120) from Moss Europe in 2006, and some 16000 miles later they are still not leaking. I just squirted some oil on them when I fitted them and did the standard jet centering procedure, entailing removing and re-fitting the jets to re-fit the jet adjusting springs.
I wonder if soaking the seals in oil for a length of time makes them swell too much, making the removal and refitting of the jets problematic?
I am using UK premium fuel, I never use the 'super'stuff.
Lindsay Sampford

I used the cork seals soaked for 24 hours. I found that the (new) jets were sticking open occasionally after using the choke. Took them off and polished them and all was well!
Neil MG

Mike - I know what you're saying but it seems to work for me. I guess a quick in and out of the jet while re-fitting the nut & spring is OK.
Neil - I agree with the polishing; they look great after a good polish up with the old 'Brasso' and I've never had any sticking of the jets either.
Love your carbies chaps!

This thread was discussed between 31/01/2015 and 02/02/2015

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