Amal

Amalgamated carburettors (known as ‘Amal’) began in the 1920s and continued to supply British machines with carbs up until the 1980s. The original Amal carburettors had brass bodies and separate float chambers, and were known as types 4, 5, 6 and 29. They were fitted from 1929 until 1933 when the body material was changed to a zinc die cast alloy. These were known as types 74, 75, 76, and 89, and can be distinguished from the later types because these have four air holes around the base of the body which the next type do not. In 1939 types 274, 275, 276 and 289 were introduced; these have two internal primary air passages in the base of the jet block. A later version with an ‘R’ suffix denotes that the primary air passage hole was moved to the air intake.
1955 saw a completely new carburettor being manufactured that had the float chamber cast in one piece with the mixing chamber, which is why it is called the ‘Monobloc’, these are types 375, 376, and 389.
1965 saw another complete redesign which produced the ‘Concentric’ carburettor which as it’s’ name implies has the float bowl concentric with the mixing chamber.
For overhaul and re-sleeving details and charges, see here.
For BSA and Ariel carb settings see here.