Overheating Dolomite 1850

[john_mcmaster@dpa.act.gov.au]

     Help!  I'm having trouble with an overheating Dolomite 1850 - I've 
     done all the bits that should be done - new thermostat (right one with 
     the long plug), flushed radiator and block, hoses checked and working 
     (not leaking) - timing is ok and the car seems to go alright.  I've 
     drilled a hole throught the thermostat so there's no air lock and 
     everything else seems to be right - water pump is working ok as well.  
     What's the secret with these things?  All help appreciated.
     
     John Mc
     '71 TR6 PI
     '76 Dolomite 1850
     'Fast is First'