TR 
  4 cylinder heads tend to suffer from severe valve seat recession; this can easily 
  be rectified on the exhaust side. The preferred solution for the inlet side 
  is to fit larger valves. It is well worth finishing the head to our Econotune 
  specification and thus make better use of the flow potential of the larger valve.
  Our Fast Road heads work very well on their own, producing a very torquey conversion. 
  To get the most from the potential of the cylinder head a change in exhaust 
  and camshaft is required. The TR4 works well with the standard twin 1 3/4" 
  SU's; however, a change to a pair of 45 DCOE Weber carburettors will pay handsome 
  dividends. 
  Our Race cylinder heads have produced 200 bhp on a fully loaded large bore engine; 
  this equates to 172 bhp at the wheels!
  The aluminium TR4 heads respond well to larger inlet valves, although this entails 
  the fitment of larger inserts for the inlet seats. Ultimately, we feel the cast 
  iron head offers more flow potential for full race use.


TR4 
  Cylinder Heads
 
  
TR4 
  Fast Road
Race 
  TR4 Aluminium head
  ..before and after!