PROFORM Wedge-Locking Header Bolts ELIMINATE the need to constantly re-tighten collector bolts, and without the need for clips, pins, racing-wire, chemicals or gunk. The secret is in the Wedge-Locking Washer's super-hardened external teeth that bite into the bottom of the bolt head and the top flange surface. Vibrations that normally cause other bolts to loosen, are blocked by the wedge-locking action that uses tension, instead of friction to stay snug. In fact, contact with oil actually facilitates the effect. Installs/uninstalls with a normal wrench, lubricate, and then reuse. Each set comes with sixteen Hex Head, Grade 8 (12.9) steel bolts (3/8-16 thread, 1 long) with a black oxide finish, and pre-assembled Wedge-Locking Washers. Product Features:Grade 8 (12.9) SteelHex Head Type1-inch LengthFits GM BB 396-502 exc 348 and 409, Ford 5.0L, SB 289-302-351W, Mopar 413
