The engines were essentially hand-built with racing in mind. Combustion chambers were fully machined to reduce variability. Nevertheless, Ford recommended blueprinting the engines before use in racing applications. With a single four-barrel carburetor they were rated at 616 horsepower (459 kW) at 7,000 rpm & 515 ft·lb (698 N·m) of torque @ 3,800 rpm, and while equipped with dual four-barrel carburetors they made 657 horsepower (490 kW) at 7,500 rpm & 575 ft·lb (780 N·m) of torque @ 4,200 rpm. Ford sold them via the parts counter, the single four-barrel model as part C6AE-6007-363S, the dual carburetor model as part C6AE-6007-359J for $2350.00 (as of October, 1968). Weight of the engine was 680 lb (308 kg).[34]