Big Block Chevrolet, Big Block Mopar 413, Small Block Ford 3/8" Diameter x 3/4" Length. black oxide. 16/pkg compatible: GM BB 396-502 (348 & 409, Ford 5.0L, SBF 289-302-351W, excluding Mopar 413 3/8" bolts) Note: 3/4" long bolts are commonly used with cast iron heads. 1 inch long bolts are recommended for aluminum heads.

Each PROFORM Grade 8 header bolt is permanently assembled with a special washer. When the bolt is torqued beyond 28 feet, the washer's super-hardened external teeth bite and grip the bottom of the bolt head and the top surface of the header. After self-locking in this manner, bolt loosening rotation is blocked by the wedge-locking action created by the washer interface, matching cam. Uphill Climbing: Vibrations can loosen the bolt and actually increase the tension on the wedge lock, further securing the bolt. It's a simple wedge-lock system that uses tension instead of friction, so contact with oil actually adds a wedge effect. When changing headers, PROFORM header bolts can be untightened with a regular wrench, lubricated and reused.


Manufacturer: ‎Proform
Part number: ‎66752
Item weight: ‎308 g
Product size: ‎15.24 x 5.08 x 12.7 cm; 308.44 g
Material: ‎Alloy steel.
Head Style: ‎Hexagonal
Batteries included: ‎No
Batteries used: ‎No
Product dimensions (Length x Width x Height): ‎15.2 x 5.1 x 12.7 cm