Old idea - New design!
This Australian designed and manufactured manifold adaptor is made to suit draw (suck) through turbo applications using a Weber (Dellorto/ Solex) carburettors.
They suit a 3 intake and are compatible with 40mm to 55mm sidedraft carburettors.
It is supplied with an internal diameter of 2" and can be increased in size if required (see last image)
There is a boss underneath for the fitment of a vacuum gauge if required.