Unleaded Cylinder Head 5 port 940 Alloy for Road/Rally
 
Hi spec all new alloy 5 port gas flowed head. The use of large valve seats and spacing means that the rocker cover might need modifying at the back to clear rockers..
 
A machined rocker covers are available for clearance problems but valves are in original centralized positions so usually no problem. Manifold studs with UNC thread for alloy type heads only are included (6 of 53K547) This 5 port std type alloy head based on the 12G1805 "S"940 casting with fully modified porting for fast road /rally use. Combustion chambers are original 21.3 to 21.5cc Beryllium valve seats with 35.7 inlets with 29.5 mm exhaust EN214N race quality valves, bronze guides with safety clips, ported and flowed to performance specification.-Weight approx. 5.7kg.
 
Machined to use with spring height valve springs with shims underneath. All heads are hipped and heat treated (annealed) from the foundry and pressure tested before machining and again after they are assembled. In the 60's the SPEEDWELL 850cc head had 1.1" x1" std valve sizes, 998/1100cc had 1.22" to 1.25" x1" and the race head had 1.32" x1.156". 
 
With modern technology and heat treatments creating a head better than most standard modified heads available with valve sizes for 1275/1380cc.
 
Ensure the use of high quality flat washers for head bolt nuts as competition head stud.
 
Suggested torque setting procedure in workshop manual sequence as follows 1st stage 15lbs/ft 2nd sgage 30lbs/ft 3rd shage 40lbs/ft final stage 45lbs/ft ===if using copper head gasket you can re torque to 45lbs but there is no need on cometic or multi.
 
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Please note: This part is bulky and may attract additional freight charges