Inlet Valves:

35.6mm(1.401") dia. Tuftrided EN214N s/steel
P/No. C-AEG543 Exhaust Valves: 29.5mm(1.161") dia. Tuftrided EN214N s/steel
P/No. C-AEG105 Exhaust seats: Latest type Beryllium-based for lead-free fuel
P/No. TAM2069 Valve Guides: Magnesium bronze
P/No. C-AJJ4037 Valve Springs: Nominal 180lb. Max actually valve lift 0.500"
P/No. C-AEA526 Stem Seals: Latest 'top-hat' design with tensioner springs (inlets)
P/No. ADU4905 Chamber Volume: Nominal 21.0cc

Modified to give maximum performance gain for cost. Combustion chambers, inlet and exhaust ports extensively re-worked. Smoothed finish in ports - not mirror-finish polished to minimise drag. Multi-angle valve seats in head. Cooper S size valves with current maximum flow profiles and Tuftrided for durability/longevity when used with unleaded fuel (hence 'black' finish). Combustion chamber volume used to maintain standard static compression ratio because head mods employed greatly increase volumetric efficiency, boosting actual running (dynamic) compression ratio.

Where much sportier cam profiles are used, a higher compression ratio is advised to achieve maximum power potential. Seek advice on what is required - a modified ECU may be required. Before fitting to engine, ensure block and head mating surfaces are thoroughly cleaned. If fitting to a new/re-machined block, clean surfaces with a grease-free cleaning agent (cellulose thinners highly recommended). Lay gasket on block (always use a good quality gasket), then fit studs - minimising gasket damage during fitment. If fitting to a previously run engine, remove all head studs so block face can be thoroughly cleaned. Remove all traces of old gasket and carbon deposits. Finish clean with cleaning agent, then continue as previously outlined. Position pistons 1& 4 at top dead centre to minimise loading on valve gear, allowing even torque-down of head. Thoroughly clean head face with cleaning agent, then lower lightly down onto block/gasket - DO NOT DROP/FORCE IT DOWN, the gasket may get damaged. ABSOLUTELY NO GASKET CEMENT OF ANY TYPE IS NECESSARY. The proper A-series head gaskets have a coating of lacquer that adheres to head and block surfaces when hot. Fit push-rods and any relevant ancillary studs (rocker posts, thermostat housing, etc.). Undo rocker adjuster screws all the way out. Fit rocker gear to head ensuring push-rod cups line up under adjuster screw ball ends. Fit head nuts (and washers where applicable) finger tight then nip down with socket in sequence described in workshop manual. Torque down in sequence to 35lb ft first, then 50lb ft. Torque forward rocker studs to 25lb ft. Set valve clearances to manufacturers recommended settings. Turn engine over by hand to ensure no spring crush is occurring.