Present embodiments related to throttle body fuel injection systems intended to replace existing carburetors. More specifically, present embodiments relate to retrofitting carbureted engines with electronic fuel injection (EFI) which may be mounted on a manifold of an internal combustion engine and have bores of differing sizes and other characteristics which allow operation of such arrangement.

Present embodiments related to throttle body fuel injection systems intended to replace existing carburetors. More specifically, present embodiments relate to retrofitting carbureted engines with electronic fuel injection (EFI) which may be mounted on a manifold of an internal combustion engine and have bores of differing sizes and other characteristics which allow operation of such arrangement.