Abstract: A main carburetor body has generally cylindrical bores into which are precisely and removably fitted liners. The inner liner surfaces are contoured as a venturi wherein a circular inlet section narrows down to a throat after which the outlet section gradually expands in flow area. Fuel discharges into the venturi through a plurality of ports in the venturi wall, these ports being located around the periphery of the venturi and generally in the vicinity of the venturi throat. Booster venturis, which in conventional carburetors obstruct the flow path, are not used. The carburetor is readily modified by removing the liners and installing a new set of liners which may have different dimensions for the venturi and a different port pattern for fuel inlet to the venturi.