This is the turned aluminium choke top piece, that holds throttle cable adjuster on original Amal TT and RN carburettors. These are CNC machined to a high standard and should fit onto any original Amal 10TT/RN carb body. Price is each.
The threaded/knurled top ring then fits over this top piece and screws down onto the carb body.
This is the later TT carb design, which used a leaf spring against the knurl to retain it - which we can also supply, that being item 0139. They are also threaded to take the later design cable adjuster and locknut - which again we can supply (although most later throttle cables already come fitted with this common design), item number 0145.
Notes on Original Amal TT and RN Top Piece Design:
It should be noted that earlier (particularly pre-war) Amal TT and RN carb design had a different type of choke top piece, made from brass and identifiable by a vertical square headed screw, next to the cable adjuster. This type used the square headed screw to lock the brass knurled top ring in place - when it was tightened it pushed out a small ball from the side, that locked the ring in place. Because it was very difficult to see if the square headed screw was tightened (or owners did not understand its purpose), these were often not loosened before trying to remove the top ring - therefore damaging and denting the top ring. Therefore this later design simplified the top piece design, to prevent unnecessary damage - but if fitting this type - it requires a leaf spring (Item 0145) is fitted behind the bellmouth lockring to prevent the top ring moving.
The earlier design also used distinctive, wider diameter throttle adjusters - which we can provide, (Item 0874), which are very pretty and distinctive of those earlier TT/RN models - but remember you will need to bore and re-thread the top cap throttle cable hole to accomodate this earlier type.