Thanks Bob, I wonder what's different about mine, is it the rear head bleeds? They reduced the cruising temperature 27F, and that will be because they bypass the thermostat. They are only small bore but had a dramatic effect. With the thermostat out I didn't think they would be significant, but now I wonder if there is some thermosyphon effect going on. I will need to try blocking them or putting an orifice in to see what happens.