[G.M.]

Driving in warm temperatures much over 75 degrees with any modern thermostats I have ever seen that fits 32 to 48 Fords will cause higher operating temperatures. You might as well use washers with about a 3/4" hole because that is how a modern thermostat will work in warmer temperatures. It will open at say the 170 degree rateing of the stat and do NOTHING after it opens, it will just stay full open all the time and act like a washer or restictor the size of the stats opening.The stats have nothing to do with cooling they only control the minimum temperature. In cold temperatures stats are required to bring the coolant temperature up to the stat rateing of say 170. If the coolant drops below 170 the stats will close until the coolant gets above 170 and keep cycling to hold close to 170. In the winter with cold ambiant temperatures and even a higher wind chill factor of the forced air the restriction of the thermost flow allows enough coolant to handle cooling under the cold ouside conditions. In the summer they open and stay open and the temperature only go's up. Stay cool. G.M.