Garages often indicate that dual carburetors (Weber, Dellorto) must be provided with F11 emulsion tubes to replace the existing F67 emulsion tubes. Is that really necessary?
Our personal experience shows that F67 emulsion tubes at least perform excellent in 40 mm Webers (Venturi 28 mm). Both the F11 and the F67 versions were tested for power and torque on a dyno tester. No difference was observed.