35.6 x 29.3mm steel valves with chrome stems and cast iron valve guides.
No by pass hose and blanked off heater outlet as per SPI heads
This specification of cylinder head is modified in true Road sport style to maximise on-road performance for those wanting maximised drive-ability when used with mild to fast-road camshaft specifications. That means optimised torque out-put through port shape and dimension development and valve throat shapes developed 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. High quality cast iron guides are used along with the latest specification chrome stemmed standard MG Metro valves (35.6mm inlet and 29.3mm exhaust) and 180lb (nominal at maximum valve lift) double valve springs to give a cylinder head capable of withstanding a maximum continual peak rpm limit of 6,500rpm and 0.475" valve lift. Combustion chambers are set at an average 21.4cc since most engines these will be used for will already be using a higher compression ratio (CR) and their efficiency will boost dynamic CR considerably. 9-stud fitting as standard. This head has no heater take-off port and no by-pass hose adaptor.
A surcharge for non-exchange purchase of £200 applies. Heads supplied as exchange units must be in good re-workable condition with no cracks, in completely standard form (no modifications), and complete with valves, springs, top caps and collets.
Some companies call this stage 3 but our way of thinking similar to original Special Tuning is as follows-for 1275 head
Stage1 has 33mm inlet 29mm exhaust std valve sizes and gas flowed
Stage2 has 35.6mm x 29mm ex road quality valves and ported to Road Sport spec
Stage3 has 35.7mm x 29mm ex race quality valves to Super Sport/Grand Tourer spec
Stage4 as stage 3 but with either larger inlet or exhasut valves and more modified throat and port work
For real race use ask our technical staff at York or Potters Bar.