carburettor overflowing

[David.H]

The (FZB) carburettor on my 1929 RK saloon (engine M101897) insists on overflowing. When I got the car it had 2 fibre washers (each ~ 1mm thick) under the needle valve seat. I put the overflowing down to worn needle/seat and as the weights were quite worn I reversed them so that the unworn part was against the float and lapped in the needle/seat. this reduced the overflow to an occasional event. The float does not leak.
At the Beaulieu day I lashed out £24 on a new (sharp) needle and new unworn seat. Replaced everything "as was" (including 2 washers) and once again fuel again poured out of the choke/air intake and squirted out of the carb top vent hole and the needle did not shut off the flow. I removed one fibre washer...no difference.
The car starts easily, runs well and there is no sign of any overflow when the engine is running - even ticking over-. I have had the new seat out & it is clear. If you balance the needle in it and blow, it seals beautifully. Pushing down on the needle does not  shut off the fuel when it is on the car. The needle does seem a bit "sticky" ....there  is no real feeling of the weights being pushed up by the float, but as I say- the float is not losing air & there is no fuel sloshing about in it!
What is the next step? It is doing nothing for the fuel consumption, not the tarmac and is a significant fire hazard (What induced Edge to put the carburettor directly over the exhaust pipe.....?)
David Harrison

The obvious answer is that the level of the fuel in the float chamber is too high. Try following Zenith's own advice in their maintenance booklet for this situation and move the collar on the needle '....a shade further from the point'. They say you should unsolder the collar first. I think you might find that the collar isn't soldered to the needle on a repro needle it just being an interference fit. 

Steve

Thank you Steve. I had read that instruction & shuddered, my soldering skills are minimal, so I hope it is an interference fit! I imagine that the idea of using more washers under the seat was to achieve a similar aim. how many should there be & how thick!? I love the accuracy of that  instruction...."a bit" ...& if doesn't work unsolder it! & try again!
I will first of all compare the collar length with my original blunt needle. Then try & move the collar without putting a flat on the point....it will go away from the point (which is good) without having to touch the point, but if "a bit" is "too much".....getting it back may be interesting!
David