Abstract: A combustion engine carburetor has a control valve assembly that generally controls flow through a fuel-and-air mixing passage extending through a body of the carburetor. The control valve assembly has at least one valve preferably of a butterfly-type having a shaft that extends transversely across the fuel-and-air mixing passage and journaled for rotation in the body about a rotation axis. The shaft has opposite trailing and leading end portions that project from generally opposing sides of the carburetor body. Axial movement of the shaft with respect to the body is limited by an axial retention feature that preferably has a radially enlarged end cap formed unitarily to the trailing end portion and a coupler snap fitted to the leading end portion.