Curly has some good advice !! It also works best if the electric thermostat is mounted in the engine block (intake manifold) and not the radiator core. The engine block thermostats do cost a little more, but they are also much more accurate. After all your concern is the engine block temperature. Best example is having a thermostat stick shut, (and these new "economy" thermostats do it more often than the old ones) the electric fan will not come on, but you engine block will be sweatin like crazy....Randy
