Pontiac 350-455 cid, uses 3/8" socket. Stainless 300 with a 12 point Head. 3/8" x 16 thread Prevent intake manifold leaks and are rated at 170,000 psi and precision machined for optimum thread engagement. Wide under head flange and companion washers provide even load distribution. ARP Intake Manifold Bolt part number 494-2101
Precision rolled threads prevent galling while promoting more consistent torque loading. Facilitates optimum sealing of gasket surfaces Washers are included.
