SB Chevrolet 180cc Bare Aluminum Cylinder Heads. Fits 4.00" and larger bore. 2.02" intake, 1.60" exhaust. 64cc combustion chambers. Manufactured from A356-T6 aluminum, they feature bronze guides, straight plug design and can accept center bolt or perimeter bolt valve covers. Each head comes with a detailed flow sheet. Ready for assembly and sold as pairs. Download Data here - DOWNLOAD Download Installation Tech here - DOWNLOAD