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 All cylinder heads are initially inspected and completely disassembled. Then the component parts are cleaned with a hot detergent wash and high-pressure rinse. Parts are next submerged in a special de-contamination tank for 12 hours. Then a further high-pressure rinse, followed by an additional chemical dip process; to bring the components back to as new appearance. The final in depth inspection includes a pressure test to check the head(s) for casting porosity. Should any porosity defects be uncovered, and having sought the clients approval, all necessary repairs are carried out. Springs, caps, cotters and bottom retainers are checked for serviceability or replacement. Valves, guides and studs are discarded. The seat inserts are machine removed, and then all guides are removed. All guide holes are checked to ensure refitting of correct size guides. The inlet ports are examined, and any porting work required is carried out. New guides are fitted. Before proceeding with any further work, a pressure test is carried out to ensure that all guides are sealing. To maintain guide to seat concentricity, oversize holes are machined for valve seat inserts from the newly fitted guides to ensure the new high quality inserts form a perfect interference fit. High quality inserts are then frozen and the head(s) heated to set them perfectly together with perfect interference fit, totally eliminating the danger of broaching the aluminium which is often a cause of early failure. Seats are then cut to correctly position the new valves (re-designed for improved flow) to the buckets and cams. The next stage is all remaining porting work and chamber polishing using dummy valves to protect seats. Valves are then individually ground in and vacuum tested to ensure a perfect seating seal. Head mating surfaces are checked and skimmed flat, then a final pressure wash and dry. Computer analysis of each individual spring for tolerance and compatibility, the fitted spring lengths are checked and the cam lifts established on our Cam doctor then each tappet is set meticulously and the head is carefully re-assembled. At signing off the comprehensive quality control (test result documents), the head(s) are bubble wrapped and securely boxed for return or taken into engine assembly. 214N stainless steel plasma nitride inlet valves Phosphor bronze valve guides Special valve seats (to suit unleaded fuel) Nuts, Washers, Bolts and fixings Tappet shims (if applicable) Special JMB camshafts Studs: manifolds Top cover & rocker covers Cam caps Tappet buckets. |
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