Have a search on the Guy Croft site as this subject is discussed there at length. My engine has the thermostat in the head. I believe the housing in the head needs to be enlarged slightly to take the thermostat. You must make sure your thermostat has a small hole in it to avoid air locks. The thermostat in my car is from a Ford Fiesta. According to people on Guy's website the best thermostat to use is a Unipart item. I can't remember the part number
![Undecided](http://131mirafiori.com/smf/Smileys/default/undecided.gif)
. As far as plumbing goes, the radiator bottom hose connects directly into the water pump and the T-piece at the top, fed from the head, needs to have one end blocked so it simply connects to the radiator top hose. Ideally, instead of blocking off one end of the T-piece, it's better to have a curved connector from the head to the radiator as water flows better round curves than right angles. My engine has a custom made curved copper connector at the head connecting it to the radiator top hose.