UPDATE
I changed the 13lb cap for a 4lb, made no difference to the temp. I pulled the thermostat and it was pretty bad. I couldn't make out which range it was in. I flushed out the radiator, took out the block drain and reverse flushed the motor until I got clear water out of the block drain. I did this three or four times and rodded the block drain between flushes with a length of wire cut from an old coat hanger. I didn't get much gunk out though.I put in a 160 thermostat that I checked was working ok and had drilled a 3/32 hole in the collar. I have still to add coolant as I wanted to take it for a run with just water in it to check if things were ok. Anyway I took it for a 20 mile run and it didn't go above 180 on a long steep incline. It sat on about 160 - 170 the rest of the time. I'll keep a close eye on it though. Thanks for all the help guys.
Bob
