Each PROFORM 12.9 Steel (equiv. Grade 8+) Header Bolt is permanently assembled with a pair of special washers. When the bolt is torqued to 28+ ft-lbs, the washers super-hardened external teeth bite into and grip the bottom of the bolt head and the top surface of the header. After being self-locked in this manner, any bolt-loosening rotation is blocked by a wedge-locking action created by the washers interfacing, matching cams. It's an uphill climb: vibration that might ordinarily loosen the bolt actually increases the wedge-locking tension, securing the bolt even more. Because this simple wedge-locking method uses tension instead of friction, contact with oil actually facilitates the wedge effect. When changing headers, PROFORM Header Bolts can be untightened with a normal wrench, lubricated, and reused.

Features:
Grade 8 (12.9) Steel
  • Hex Head Type
  • 1-inch Length
  • Fits GM BB 396-502 exc 348 and 409, Ford 5.0L, SB 289-302-351W, Mopar 413
  • PROFORM Parts Brand Product
  • Sold as One Set of 16 Pieces
  • More From This Category

    Proform , PROFORM Circle Track 750 CFM Carburetor, E85, Circle Track Model

    Proform , PROFORM Circle Track 750 CFM Carburetor, E85, Circle Track Model

    $2,163.88

    Proform , Mini Valve Spring Tester 0-300 lbs Range, 5 lbs Measuring Increments

    Proform , Mini Valve Spring Tester 0-300 lbs Range, 5 lbs Measuring Increments

    $158.95

    Proform , Adjustable Knob Model Silver RPM Shift Light, Silver/Yellow; Adjustable Knob Model; 3000 to 12,000 RPM

    Proform , Adjustable Knob Model Silver RPM Shift Light, Silver/Yellow; Adjustable Knob Model; 3000 to 12,000 RPM

    $114.40

    Proform , PROFORM Circle Track 650 CFM Carburetor, Gas, Circle Track Model

    Proform , PROFORM Circle Track 650 CFM Carburetor, Gas, Circle Track Model

    $1,918.32

    Proform , Radiator Overflow Canister , Billet Aluminum; Natural Finish

    Proform , Radiator Overflow Canister , Billet Aluminum; Natural Finish

    $222.00