This billet base plate adaptor allows you to use any stock 2V/4V air cleaner (5 1/8" neck) on your stock Carter or Motorcraft YF/YFA 1V carburetor. Includes a custom made center stud, which is used to mount the base to the carb. The center stud is also used to secure the air cleaner, using a standard 1/4x20 stud and/or bolt.