The Edelbrock #1126 Ford Flatheads feature a block logo design for Fords and Mercurys, and are casted at the Edelbrock Foundry in the USA of T-6 tempered A356 aluminum. The Edelbrock #1126 heads are rugged, ribbed internally and externally, with a large water capacity and excellent breathing characteristics. The 65cc heads support 8.0:1 compression ratio on blocks with a 3/16" base relief (stock bore and stroke), compression ratio increase is approximately 3/10 of a percent with each 1/8" stroke.INSTALLATION NOTE: • Flathead head copper gaskets for 1938-48 use Victor #3036; or Fel-Pro® #7548; or Edelbrock Head Gasket Set #7394; for 1949-53 use Fel-Pro #1055 and Fel-Pro #1056 or Edelbrock Head Gasket Set #7393. • Recommended spark plugs are Champion RC12YC or equivalent 14mm x 3/4" reach with flat gasket seat. • Head stud kit for 1938-48, use #8505 • Head stud kit for 1949-53, use #850. • Generator stud kit for 1938-48, use #8506.