This specification of cylinder head, based on used core castings, is modified to current fast road style to maximise fast road and track day/weekend-warrior performance when used with fast road and road/rally camshaft specifications. That means optimised BHP and torque out-put through port shape and dimensions and valve throat shapes developed on airflow bench and dyno/rolling roads to work with the aforementioned camshaft types, along with suitable compression ratios given modern lead-free fuel specifications. Genuine Rover copper-beryllium lead-free exhaust seat inserts are fitted. Latest specification manganese-bronze valve guides are used along with the latest specification plasma-nitrided EN214N stainless steel (35.7mm inlet and 29.5mm exhaust) and 220lb (nominal at maximum valve lift) double valve springs to give a cylinder head capable of withstanding a maximum continual peak rpm limit of 8,000rpm and 0.500" actual valve lift. Suitable for auto-testing, hill-climbs and track day use. Combustion chambers are set at an average 21.4cc since most engines these will be used for will already be using an elevated compression ratio (CR) through either smaller capacity dished pistons and/or larger bore capacities, and their efficiency will boost dynamic CR considerably. 9-stud fitting as standard.

This head has the heater take-off port open and a by-pass hose adapter fitted.

Modified to give maximum performance gain for cost. Combustion chambers, inlet and exhaust ports extensively re-worked. Stone-ground finish in ports promotes ultimate fuel atomisation. Three-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 give slight static compression ratio increase over standard. 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.

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.

If no by-pass hose is being used, it is essential to drill 4 to 6 1/8"-diameter holes in the thermostat outer ring to allow coolant circulation prior to thermostat opening. If no thermostat is being used, a blanking sleeve MUST be fitted. Failure to use either method will result in localized over-heating, causing excessive heat leading to pre-ignition, detonation, piston failure and cracked head. Water pump port must be blanked off (can use blanking plug CAM4126 and clip 3H2963.