Every cylinder head is inspected for cracks. Valve guides are measured for wear and either resized or renewed to conform to original tolerances. Valve seats are machined so as to retain the correct seat angles, widths, valve heights and valve seating concentric with the centre line of the valve guide bore. Valves are replaced. All valve springs are tested for squareness, free height and compressed load length. Cylinder heads are checked for distortion and thickness. When machining the cylinder head face, particular attention is paid to maintaining the correct surface finish specified by the gasket manufacturer. On all our engines we grant with professional installation 24-month guarantee in accordance with our general terms of trade.