Needle, needle jets, and the Amal Concentric
The Amal concentric carburetor was introduced as a cost saving measure dictated by
the British companies to IMI Components, owners of Amal carburetors LTD. The first
of these came fitted to the BSA Spitfire MK 3 in 1967 and most of the factories followed
shortly after. The first Concentric had a removable pilot jet threaded into the
base of the body. They also used the shorter 622/063 needle and early non-cross
drilled needle jet 622/079-106 along with the short needle jet carrier 622/080. These
components were changed for 1969 to the updated parts needle 622/124, needle jet
622/122-106 and the needle jet carrier 622/128. Amal sold these components as a set
to update older carburetors as Amal number 622/235 conversion set.
Wear and corrosion take a big toll on these components and it is good practice to replace
the needle and needle jet as a set when they have been in service for more that
10,000 miles or even less under dirty conditions. It is amazing how much these components
can improve running and mid range throttle response. The early and late
components are never to be mixed in service.