|Today with a temp of only 97Deg F, I used the car for the first time with the new Big Bore Thermostat, 82C/180F.
Once warmed up on the highway, the temp gauge sat below normal, in fact just to the left of the 'M' of 'Made in UK' on the bottom of the gauge. Slower in town, it was just the same. At traffic lights there was no noticeable rise in the needle after a minutes wait and the fans did not come on.
Once home I let the car cool down for 2 hours with the engine in the sun and the rear of the car in the shade. The front wing temp was 147Deg F and the rear was 98Deg F. I started up and let it tick over at just shy of 1000 rpm with the bonnet down. When the fans eventually came on, I took the following temps with a digital thermometer, one without a laser pointer, right up against the measured item. Top hose, 177Deg F, Top of Rad, 108 to 116Deg F, Bottom hose, 172Deg F. I then let the car idle for a further 20 minutes with the bonnet shut and the temp gauge needle exactly dissected the 'N'. The fans stayed on all the time.
I turned the engine off and the fans ran on for a further 8 minutes. During this heat soak time the gauge rose to just above 'UK' of 'Made in UK'. I took further temps. Top hose 179Deg, Top of Rad 103 to 106Deg F, Bottom hose 106Deg F.
You have to bear in mind that I have an aluminium rad and Forlife coolant, but the car appears to me to run significantly cooler and when left for a long tick over, the needle would previously have gone well past the 'N'.
Time will tell by driving the car more, but my very un-scientific test leads me to the conclusion that an MGB GT V8, whose owner believes, that it runs hot, will run much cooler with the investment of 12.48UKP, and the driver will be less steamed up over it as well. In short, a good investment, which has been stated previously.