For a long time I used to change over between a summer 82c thermostat and a winter 88 thermostat but I have not done it for a number of years. I have just put up with the engines running a bit colder in the winter.
However this year one of my cars seems to be running very cold, about a 1/4 on the temperature gauge so I am about to change the thermostat. The heater does not seem to be as hot as my other cars so I do not think it is a temperate gauge / sender problem. On getting ready to do this little job I note that some thermostats have a small hole in them with what I assume is an associated valve. See photo.
Both the official Workshop manual and the Haynes manual show thermostats with holes but I have a number that I have used in the past that do not have any holes. Can anyone advise me as to the best type to use.
I have also read in the Moss Spitfire catalogue that there is a hot climate thermostat GTS 102 (74c) is this something we should be using now to prevent overheating problems?