PROFORM Header Bolts Grade 8 Wedge Locking 3/4" GM V6/ SBC 265-400



  • Direct Fit Upgrade
  • Locking Bolt Design
  • Complete Set
  • Grade Eight Durability

PROFORM Grade 8 Wedge Locking 3/4" Long Header Bolts for GM V6 and 265 to 400 Cubic Inch SBC.

Installing new headers on your small block Chevrolet or V6 engine? These high-quality PROFORM header bolts (66751) are the perfect addition! Their locking design will securely hold them in place when installed.

Features and Benefits:
- 3/8”-16 thread diameter
- ¾ inch long
- fits GM V6 and 265-400 small block
- set of 12

Grade 8 Header Bolt is permanently assembled with a pair of special washers. When the bolt is torqued to 28+ ft-lbs, the washer's 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. Because this simple wedge-locking method uses tension instead of friction, contact with oil facilitates the wedge effect.

When changing headers, PROFORM Header Bolts can be untightened with a normal wrench, lubricated, and reused.

Vehicle Fitment: 1960-1987 C10

California Residents: Proposition 65 Warning

Vehicle Fitment

This product will fit the following C10 years:

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