Insert for IC engine inlet manifold - has internal and external spiral profiles to improve homogeneity of fuel air mixture

The insert has a cylindrical body (10) with a flange (16) by means of which it is bolted inside the suction manifold between the carburettor and the enqine. The inside of the insert has a venturi profile which accelerates and then retards the mixture flowing through it. This action improves the homogeneity of the mixture. The outside of the insert has spiral grooves (24) into which spiral tongues (26) are inserted. The tongues continue inside the manifold beyond the end of the insert. Their projecting portions have serrated teeth which induce turbulence and prevent condensation of fuel droplets on the wall of the manifold.