Carburettor adaptor / manifold connector, screws into head for spigot mount carb, Suit Norton overhead valve head. Aluminium, Overall length: 2-9/16 inch; OD mounting boss 1-1/8 inch, Threaded end 1-3/8 inch 26tpi, hole centres 2 inch, threaded 5/16 inch BSW. Allows monobloc or concentric carb to be fitted to pre 1955 headsOriginal part number9132; A3/154 - Carburetter (sic) Adaptor