All Raceline Duratec cylinder heads are developed in collaboration with our CNC cylinder head machining partner, designed and modelled with the latest CAD-CAM techniques and machined using the very latest CNC machining techniques. With our combined knowledge of performance engine design, together with latest testing, design and machining ideas we are able to offer superior, CNC modified cylinder heads that comfortably outperform any other comparable cylinder head on the market today.There are three basic Duratec cylinder head specifications that Raceline offers:PHASE 1 – Ford Duratec high-port cylinder head CNC port-machined and retaining the original 35/30mm valve sizes.PHASE 2 – Ford Duratec high-port cylinder head CNC port-machined for 1mm oversize 36/31mm valves sizes. Valve seats CNC reprofiled to retain original valve seat inserts. Valve clearance will be obtained using standard Ford graded cam followers. 36/31mm valves available separately.PHASE 3 – Ford Duratec high-port cylinder head CNC port-machined for 2mm oversize 37/31mm valves sizes. Lage valve seats inserted and CNC reprofiled. Valve clearance will be obtained using standard Ford graded cam followers. 37/31mm valves available separately.Please phone for further details.