Davies Craig Mechanical Thermal Switch 0401

[lombardi]

Anyone fitted one of these to a 105 2lt , my 1974 spider has been set up has the fan constantly runs , so have bought one of these , are they easy to fit and what temp should i set .

[Colin Byrne]

Sorry haven't fitted one of these, never been a fan of jamming the probe in between the radiator hose and the outlet, although I see that they DC now make a plastic adapter so you don't need to do this.  However they should be pretty easy to install.  I'd be putting the sensor on the top water outlet after the thermostat before the radiator so you're controlling around the temp of the engine, rather than the outlet of the radiator.  I'd also put the probe at the bottom of the pipe, to make sure it is actually in water flow in case the water level drops for some reason.
As for the temp setting, your aim is to keep the water temp around the opening of the thermostat, I think the standard thermostat opens at 85 deg?? (I've got a low temp one 77deg in my car) so you want it above that.  Not sure if the this switch has any hysteresis in it (hopefully it does) if so you want the off temp just above 85 deg as well.  It's a bit hard to give exact details as your settings will be determined by how effective your fan and cooling system are.
I've got an DC electric water pump it ramps up its speed from 50deg = %50 to 80 deg = 100% my fan then switches on at 82 deg and switches off at 80 deg.  With the ali radiator, big 13" electric fan and the electric water pump, even on very hot days, at idle the fan only needs to come on for 30 seconds or so to keep the temp under control

[lombardi]

Thanks Colin, will follow ur instructions