Holden 253 304 308 12 Point Black Oxide Intake Manifold Bolt Kit They are manufactured from cast

They are manufactured from cast aluminum and are offered with breather holes or without any holes

Speedmaster aluminum valve covers feature a classic raised

Made from premium materials and built to exacting tolerances

Provides very positive shifts for high performance street use or for competitive events

Holden 253 304 308 12 Point Black Oxide Intake Manifold Bolt Kit They are manufactured from castSpeedmaster black oxide coated chromoly intake manifold bolts are rated at 170,000 psi. They're precision machined for optimum thread engagement and have a wide area flange for better load distribution. They also feature precision rolled threads, which prevent galling, while promoting more consistent torque loading.