Top ring retainer spring as fitted behind lockring of bellmouth on original later type Amal TT carbs, and stops top lockring from loosening. This one, as per original item, in plated spring steel.
Note : earlier Amal TT (and all RN type) carburettors used a different method of locking the top ring - this being a brass type top cap with a square headed screw in the top of it, that when tightened down, pushed out a lock pin that gripped against the inner face of the threaded top ring. These are often identifiable - because the inner top ring will often have score marks where a previous owner has tried to unscrew the top ring without loosening the square headed screw!
Sorry, but we do not offer a reproduction of this earlier type mixing chamber top cap (although we do sell the wider distinctive throttle cable adjuster that fitted in them - see Item 0874, which also shows an example of the earlier top), but we do sell the later top cap that was used in conjunction with this spring - Item 0138. If you are not sure which type of TT carb body you have - then the TT carb to accept this type of leaf spring will have a small indent underneath the main body casting at the point the bellmouth screws in, this is to accept the spring 'stop' and ensures the spring does not rotate while you are unscrewing the top. This is shown in the second photograph.
If you have the earlier type carb, but the carb top (mixing chamber) is no longer working - the small indent mechanism often jams, then it is possible to fit this later type of spring to stop the threaded ring coming loose, but you would either have to grind off the small tab at the base of the circle of this spring (my preferred method), or mill a small slot in the base of the carb body as per photo. In reality, the tightened bellmouth lock ring should be enough to keep the spring in place when unscrewing/screwing the top ring - but I know I have just held it with my fingers in the past, to stop it trying to rotate.
Update May 2020: Just had a new delivery of these, and have actually been able to reduce price slightly due to having a much bigger batch made this time