Primarily designed for use on 1939 to 1948 Ford flathead V8 engines. May also be used on 1949 to 1953 Ford flathead V8 engines, subject to minor modification. One of the best flowing flathead V8 cylinder heads ever produced! ELCO cylinder heads require the use of a Vertex style angle drive to accommodate a 1929 to 1941 Nash Twin 8 Distributor for ignition purposes. Ford 8BA flathead front timing cover may also be used. Compression ratio: 8.25 to 1.