The Italian bred original WEBER 2 stage, twin barrel carburetor designed by Edoardo Weber in 1920 has a long history of fueling the most exotic street and race cars in history. Ferrari, Fiat, Alfa Romeo, Aston Martin, Lamborgini, Lancia, Lotus, Porsche, BMW and Triumph have rolled to the winner's circle many times sporting WEBER carburetors. Prior to fuel injection Weber has been the quintessential, ultimate street and race carburetor for power, reliability and efficiency. Not only was it adopted by VW, Toyota , Datsun and Ford, it was also, cloned by other manufactures such as the Holley 5200.
In 1990 production moved from Bologna, Italy to Madrid, Spain. Also, Magnetti Marelli in the UK, Redline and Interco in the US had licensing rights to build and distribute WEBER carburetors.
Granted, for authenticity and originality and aesthetics, a shiny pair of SU's HS4s look great on a British motor car. If they are relatively new and meticulously calibrated, synchronized and tuned they give adequate performance appropriate to their vintage era. Twin SU's HS4s certainly still have a wonderful place under the bonnet of the chrome bumper MGBs and other Brit cars of the late 60's and early 70's. The rubber bumper MGBs are another story. Burdened by heavy bumpers, raised ride height, power robbing emission controls and the marginal Zenith Stromberg carburetor, the 1974 to 1980 MGBs suffered in both the handling and performance area. These cars are the perfect candidates for the WEBER upgrade.
After total detox (per John Twist, University Motors publications) including removal of the pollution control devices, the air pump, gulp valve, EGR valve and catalytic converter and an engine rebuild, the Weber 32/36 DGEV or the 34/34 DGEC are perfect mates for the 18V engine. The side-draft DCOE should be reserved for race applications. The rebuild should include a overbore of +40 or +60, mild port and polish, a new stock cam, new high performance pistons to increase CR from 8.8:1 to 9.4:1 and new stock valve train with 1.625 inlet valves. These upgrades plus a Pertronix ignition system and K&N air filter will increase performance beyond all expectations. The Weber carbs must be tuned to the new engine displacement, and the main jets replaced or reamed taking into consideration the use of 93 Octane fuel with 10% Ethanol.* This may require both main and idle jet changes and a slightly rich A/R ratio around 13.5/1 with CO < 5%. In order to pass emissions testing, lean out the mixture prior to testing. Some states may require adding back a low restriction catalytic converter to meet the NOX standards. Making a good thing better with new technology will make our loveable MGBs even more enjoyable.