Our 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 our 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.