In "Parts to Look For" on ford-y-block.com, John said that although the 1957-59 FEK/FEH distributors have centrifugal advance, they have too much advance for performance use. He went on to recommend 1959-up distributors for performance applications. My 57 tbird tach-drive distributor is an "FEJ," which falls into the FEK/FEH category. At what performance level should the 57-59 FEK/FEH/FEJ distributors not be used?