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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - SU Carburetor Throttle Shaft vacuum leak - Tip

SU Carburetor Throttle Shaft vacuum leak - Tip

If you throttle shafts develop a vacuum leak due to wear, the following may be a stopgap solution. In order for this to work, the shafts must not be excessivly worn that they wobble and they must protrude at least 1/8 inch beyond the carburetor. Find an “O” ring with an ID that is slightly less than the diameter of the shaft and with a 1/8 inch cross sectional diameter. First apply a thin coat of silicone grease to the shaft ends. Then use an epoxy adhesive (JB Weld is a good choice) and carefully apply glue to the carburetor body ensuring that no adhesive is applied to the shaft. Slide the “O” ring onto the shaft and apply more adhesive to the “O” ring where it meets the carburetor to ensure a good seal.

You can check for vacuum leaks by spraying a flammable solvent such as carburetor cleaner at all possible leak locations while the engine is running at idle speed. If the engine RPM changes you have a leak at that location.

Frank Grimaldi
Frank Grimaldi

I wonder if the valve stem seals would work? I've got a mountain of them.

Gird Clark
Rockburn, Qué
Gordon A Clark

Unfortunately, you don't usually recognize that the shafts are worn until they are too far gone for this temporary repair to work. Bite the bullet and have them re-bushed with new shafts when you see the idle fluctate.

I saw a car where the owner had wrapped Saran Wrap and rubber bands around the leaks to try to improve things. Didn't work.

My .02

Tom Lange
Bar Harbor, Maine
t lange

I know JB weld is good stuff and I use it occasionally, but it is not for anything and everything. My first TD I purchased in '74 had the spark plug wires held in place in the distributor cap with epoxy. The ignition switch was held in place with epoxy. If epoxy is your thing then use it for everything but don't spread it around.

Rob
r starnes

This thread was discussed between 29/09/2011 and 05/10/2011

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