In the 1960s AMAL became part of the IMI group of industries before being sold in 1993 to Grosvenor Works Ltd in North London: a family run business specialising in supplying components to various fuel systems companies. Grosvenor then began revitalising the AMAL product range by commencing a programme of re-introducing some of the more popular ranges of obsolete product.
In 2003 the business was sold to Burlen Fuel Systems Limited, a company that also produces SU, Solex and Zenith, three other "classic" carburettor ranges. Burlen Fuel Systems have increased the range of popular obsolete carburetters in production.
The 'AMAL' and 'AMAC' trademarks also cover a range of products including controls (brake and clutch levers, cables, etc.), fuel lift pumps, gas jets and burner devices as well as gas safety valves.
76 & 276 Series Carburettor Types ("AMAL Standard" series) can be spigot or flange fixing with adjustment screws on the left or right hand sides of the carburetter body. The available bore sizes are 15/16", 1" and 1 1/16" diameters. The 276 type carburetter is, in virtually all aspects, identical to the 76 version, except that the main emulsion air is drawn from inside the air intake (air filter) whilst the 76 carburetter uses unfiltered air. The 76 types are of diecast zinc construction and were introduced in the early 1930s, replacing the earlier 6 series, which were of bronze construction, although basically the same design. The 276 type was introduced in 1940 in an attempt to improve the carburetter's durability in dusty and dirty operating environments. In the same design range were the 4 and 5 types with smaller bore sizes and the 29 type with larger bore sizes. These were replaced with the 74, 75 and 89 and then later, by the 274, 275 and 289 carburetter types. The float chambers for all early carburettors (including these types) were separate assemblies from the carburetters and were generally attached to the carburettors by connections made under the main jet. Depending upon the physical size and arrangement, these separate float chambers were designated types 1, 2, 3 & 4 in the main carburetter specification numbering and were assembled from components generally in the 64/ component part number sequence.
This high performance carburettor was developed during the 1940s from the earlier pre war type 27. The mixing chamber body is either of the spigot or flange type mounting. The flange type has two options of a long or short delivery choke. The bore sizes can vary between 1 3/32" and 1 7/32". The throttle slide, with its centrally mounted needle and jet arrangement, was later repeated on the later designs of concentric smoothbore carburettors. The enrichment air slide is mounted separately to the throttle slide bore and provides a simple enrichment for cold starting. The unit can be used in conjunction with either a separately mounted float chamber or with a rigid float chamber of either top or bottom feed. The flange type carburetter has a recently been re-introduced by Burlen Fuel Systems Ltd in both the short and long delivery choke. Development is currently under way to produce a replacement rigid float chamber utilising components from the 276 series. Remote mounting float bowl applications can be satisfied using the 510 ("Matchbox") float chamber.
Current production is based on the T3GP model which was made in 1 3/8" and 1 1/2" bores sizes originally designed in the very early 1950s; these are the only sizes produced now. The original range covered sizes from 1" up to 1 1/2" bores in various body dimensions. The GP design was the last in a series designed specifically for racing engines that started with the type 27 in the 1930s; was developed into the TT type with an enrichment (or emulsion) air slide located outside of the throttle slide bore; and then through to the RN (remote needle) type, where the throttle needle itself was located outside of the throttle bore. This feature of remote needle was then carried through to the GP design. After the GP design was reintroduced into production by the AMAL Carburetter Company, it was a further development of the range, which became known as the GP2 type, where the pilot circuit air supply was arranged to come from filtered air. The majority of the carburetters produced were of the flange fixing type, although spigot mounted and remote mounted float chambers were all utilised, but currently only the remote mounted ("matchbox") type 510, is used.
This range (generally known as the "Monobloc" type), was produced from 1954 in a range of sizes matching those of the AMAL "Standard" range in body types designated 363, 374, 375, 376 and 389. This carburetter type replaced the "Standard" series with the design intention of lowering production cost / complexity and reducing the major fault of the "Standard" series which was fuel surge due to the remote location of the float chamber. The monobloc (one piece, hence the name) design incorporates the float chamber into the carburetter body casting, although it is still located to one side of the main fuel metering circuitry. The bore sizes currently manufactured are 15/16", 1" and 1 1/16" diameter for the 376 body type and 1 1/8", 1 5/32" and 1 3/16" for the 389 type. The range originally supplied included a 389 in 1 5/32", and the 375 in 21/32", 23/32", 25/32", 13/16" and 7/8".
These were developed with the float bowl arranged centrally around (concentric with, hence the name) the main jet in order to remove the sensitivity to fuel surge inherent an all the earlier designs. They were introduced into production in 1967 in two body sizes (600 series and 900 series) covering bore sizes from 22 mm through to 32 mm. The design catered for both left hand and right hand positioning of adjuster screws, but only flange fixing to the engine. They still utilised the cold starting mechanisms of the "Standard" and "Monobloc" ranges, i.e. enrichment by float bowl flooding (tickler) as well as enrichment by restriction of intake air (air valve within the throttle slide bore). With its compact design, the "Concentric" design was the simplest manufacturing arrangement of the AMAL range and all the earlier "Standard" and "Monobloc" specifications were replaced by "Concentric" applications, although the timing of its introduction of the product range was such that only two or three years after its introduction the bulk of UK motorcycling manufacturing had disappeared. It therefore did not have the very large OE volume demands of the carburetter types it replaced. The more common sizes were the 600 in 22mm, 24mm, 26mm and 27mm, and the 900 in 28mm, 30mm and 32mm.
Mark 1 1/2 Concentric Series Carburettor Types - were virtually identical to the Mark 1 series, except in that the tickler and air slide cold start enrichments were replaced by a cold start system having its own fuel and air supplies, separate from those of the main carburetter. Body and bore sizes are as for the Mark 1 range. The main market for the product range was on Spanish motorcycles, although a few were used on very late model Triumph engines.
Introduced into production in 1974 and designed to replace the Mark 1 1/2 range, these carburettor types are constructed of aluminium, rather than zinc alloy, diecastings. They incorporate the design features of the Mark 1 1/2 regarding cold starting circuitry, but otherwise have circuitry that is similar to earlier products. The range is manufactured in three body sizes (2000, 2600 & 2900) and within these body types, bore sizes from 22 mm to 40 mm. Within the 2000 type body types, there is a "smoothbore" (i.e. similar arrangement to the 276, 376 and GP) arrangement with a "jet block" allowing a smooth airflow through the carburetter. The smoothbore arrangement is popular for racing applications.