For BBC CHEVY 454 Fabricated Aluminum Valve Covers Polished 427 Big Block Chevy 396 They are Big block Chevy fabricated aluminum valve covers Fits 1965-95 Big Block Chevy 396 427 454 502 engines Fabricated anodized aluminum smooth finish. Constructed with 1/4" thick billet rail.3 11/16" Tall style to clear most roller rockers. One 1.25" Hole on each valve cover,Will clear almost all valvetrain combinations