Stub stacks are used on SU carburettors to improve airflow and performance. Specifically, they are short, bell-shaped intake adapters that smooth out the airflow entering the carburettor by reducing turbulence and enhancing the venturi effect. This helps increase the efficiency of air-fuel mixing, leading to better throttle response and, in many cases, a slight boost in power.
By smoothing the transition of air from the intake to the carburettor throat, stub stacks reduce restrictions and improve the volumetric efficiency of the engine. They're commonly used in racing applications to optimise carburettor performance.
New.
33mm aperture flaring out to 43mm intake diameter, height 12mm.