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Triumph TR3 - SU Carb Leaks No More

On the topic of unwanted gas...

Here's an update on my persistently leaking carburetor for which I posted an SOS last year. I finally got it to stop leaking and wanted to share what I think did the trick.

To recap, my front carb was leaking gas both during operation and after parking. The leak was coming at the base of hollow bolt that connects the float bowl arm to the underside of the carburetor body. The carb would leak until the float bowl dumped the majority of its load of gas (i.e., for quite some time after parking. Not pleasant, and, I know, not safe.

I rebuilt both carburetors. No impact.

I replaced the washers (both metal and fiber) and the hollow bolt that mounts the float bowl to the carburetor body. I was convinced the leak was coming through this union. I even installed the alternative hollow bolt available through Moss. No dice.

With the carb body once again on the workbench last weekend, I noticed how rough and uneven the surface was on the carb body where the hollow bolt mates up against it with a fiber washer. Willing to try anything, I proceeded to file this surface down until it was perfectly smooth and flat, with no gaps or ripples. With that done, I bolted up a new "traditional" hollow bolt and fiber washer, installed new rubber washers for the float bowl arm, and put the whole mess back in the car. (Having the carbs out provided a perfect opportunity to finally address the contacts on the balky starter motor which now works "smooth as silk.")

Voila. Leaks-no-more.

Ok...I also rebuilt the jet assembly again, this time using two of those rubber o-rings in lieu of the cork ones. It went together much more easily, and the jet lowers and raises much better in response to the choke cable. But I don't think this was causing the leak, given where the gas was accummlating.

Domestic life is greatly improved with the smell of gasoline no longer permeating our garage. I feel much, much safer, and, hey, mileage should increase dramatically!

Bill Stagg
1961 TR3A (which leaks-no-more)
Bill Stagg

This thread was discussed on 24/11/2003

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