Small Block Chevy Vortec Center Bolt Valve Covers (NO BREATHER HOLES). (FITS SMALL BLOCK CHEVY ONLY). Vortec Center Bolt Valve covers (FITS SMALL BLOCK CHEVY ONLY). Features Black Powder coated surface and NO Breather Holes! These are the CENTER BOLT design and come with everything needed for mounting. Tall style will clear roller rockers. If …