Fits 1965-1990 Chevrolet 396-454 Big Block and 1962-2001 Ford 221-351W

Designed for make header installation easier and heat-treated for extra strength. The special washer faced, smaller-than-standard hex head is for tight spaces. These bolts are grade 5 with a 7/16 inch hex head and a protective black finish, except where noted. Set of 16. 3/8 inch-16 x 3/4 inch.