We probably all know that you can choose a thermostat that opens and closes at several temperature combinations. My L24 FSM says the stat should open (and close) at 180 F. Fine and dandy.

But now I'm putting a 3.1 L stroker motor in my car and adding a Vintage Air A/C system and a 2450 CFM Perma-Cool electric fan as well. So, I need to get a thermal switch to operate the fan (which will also be activated by the trinary switch on the A/C system).

Assuming that a 180 F turn on temp is OK for the stroker, the question is at what temp should the switch turn off and is that even important? Almost every switch I see online has a 165 F turn off point. I presume that is fine because any running engine should be at about 180 F when it gets turned off and the fan would be running.

But I want to check with folks more expert in these matters and that's you fine people. Am I worrying about nothing?

Are you trying to trigger it from your thermo housing?

Yes. My thermostat housing (no idea what model it came from) has an amazing 5 ports so one for the temperature gauge sending unit, which is already installed along with an EFI sending unit, and one for the fan switch. One port is already plugged so I'll leave that alone and plug the others as I'll have triple Weber carbs with no need for a water line as was used on the OEM SU manifold.

On another thread, EuroDat gave this info.

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I think the sizes are as follows. You should be able to find a M12 easy enough or tap the 1/4" out to 3/8" NPT.

Temp gauge: M16×1.5mm

Thermotime: M14×1.5mm

Water temp: M12×1.5mm (for fuel injection control)

Water temperature switch: 1/4" BSPT. (Not the same as NPT. Has 19 threads per inch and NPT has 18.)

Why on earth Nissan decided to use BSPT on that one port is beyond me. Some folks use a BSPT to NPT adapter to get a sensor in that port but I'm hoping it can be drilled and re-tapped for 3/8" NPT. Has anyone done this?

Edited 4 hours ago4 hr by Seppi72
additional question

Check out the housing ZCD sells. I bought this for my resto. Worked beautifully, A little pricy but has everything you need thread wise. I’ll post a pic.

Let me know if you want info on the 2pole Bosch sensor.