Carburettor & airfilter More sub catagories: carburettor & air filter

New products nut 5/16" UNF from 0,35 EUR incl. 19 % tax excl. spring washer 5/16" from 0,25 EUR incl. 19 % tax excl. washer 5/16" outer diameter 11/16", thickness 1.6 mm from 0,15 EUR incl. 19 % tax excl.

The original 100-Six BN4 model had two SU carburettors of type H4. This indicates that they were 'horizontal' carburettors - the air flow through the carburettor was horizontal, although the bellhousings were vertically mounted - with 4 indicating the 11/2in size of the venturi (4 being the number of 1/8ths over an inch of the size). The standard needle was AJ. These carburettors were one reason for the restricted performance of the original engine previously described they were replaced by a pair of 13/4in semi-downdraught (mounted at an angle) HD6 carburettors with standard needle CV.

These carburettors were carried forward on the 3000 Mark I models, but for a short interval (July to November 1959, chassis and engine number change points listed in 'Production Changes') they were fitted with an automatic choke device in the form of a thermostatically-controlled auxiliary carburettor, fitted adjacent to the rear carburettor and drawing its fuel supply directly from the float chamber of this. Cars equipped with this device did not have a choke control on the facia, and when the manual choke was re-introduced the choke control was moved from its original hiding place under the facia to the main panel above the heater controls.

The big change on the Mark II model from chassis number 13751 in 1961 was that three carburettors were now fitted, SU type HS4 11/2in semi-downdraught, with standard needle DJ. Later versions of these carburettors, from engine number 29E/2995 in November 1961, were fitted with nylon instead of metal floats. Also during the three-carb production run, the carburettor balance pipes were increased in diameter, overflow pipes were improved and the heat shield was covered in asbestos on top as well as on the underside - all in an effort to overcome a problem of fuel vaporising in the rear carburettor.

Although the triple-carburettor set-up gave a valuable increase in power (and also apparently permitted the installation of three Weber carburettors on works cars), they were not totally satisfactory in service as there were usually problems with adjustment and tuning. So on the Mark II Convertible model, type BJ7 with engine type 29F, a reversion was made to the twin-carburettor set-up, now with two HS6 (13/4in) carburettors, standard needle BC. Finally, on the Mark III model in 1964, type BJ8 with engine 29K, a pair of HD8 2in carburettors with standard needle UH were fitted. These are instantly recognisable with their fatter and shorter bellhousings. It is worth noting that whereas the 100-Six and 3000 Mark I carburettors had hexagonal brass tops, on all 3000 Mark II and Mark III models the carburettors had black, knurled plastic tops. On all six-cylinder cars, each carburettor had an individual Coopers pancake type air filter, usually painted engine colour.