Each PROFORM 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. Its 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
  • 3/4-inch Length
  • Fits GM V6, SB 265-400, Buick, Olds, Pontiac '79 and earlier, Mopar BB 383-440 exc 413, AMC V8's w 3/8" bolts
  • PROFORM Parts Brand Product
  • Sold as Set of 12
  • More From This Category

    Proform , Rebuild & Repair Kit for 450-780 CFM Carburetors, For Carburetors w/ Vacuum Secondary

    Proform , Rebuild & Repair Kit for 450-780 CFM Carburetors, For Carburetors w/ Vacuum Secondary

    $135.51

    Proform , MOPAR Big Block Engine Dress-Up Kit, Black Crinkle with Signature Blue MOPAR Emblems

    Proform , MOPAR Big Block Engine Dress-Up Kit, Black Crinkle with Signature Blue MOPAR Emblems

    $644.69

    Proform , Chevrolet Big-Block Slant-Edge Valve Covers, Chrome; Tall; Raised Blackfield Emblems

    Proform , Chevrolet Big-Block Slant-Edge Valve Covers, Chrome; Tall; Raised Blackfield Emblems

    $906.77

    Proform , Chevrolet Starter 4.41:1 Gear Reduction, 168 Tooth Flywheel

    Proform , Chevrolet Starter 4.41:1 Gear Reduction, 168 Tooth Flywheel

    $362.57

    Proform , Starter Shim Kit , Fits Part Nos. 66256, 66258, 66259, 66266, 66267

    Proform , Starter Shim Kit , Fits Part Nos. 66256, 66258, 66259, 66266, 66267

    $20.31

    Proform , Ford Auto Trans Starter 2.2KW; 15:1 Ratio, For Ford Small & Big Block V8 Engines; 221- 351W and 460 Engines

    Proform , Ford Auto Trans Starter 2.2KW; 15:1 Ratio, For Ford Small & Big Block V8 Engines; 221- 351W and 460 Engines

    $502.40