Replace thermostat or replace fan switch?

[64stpside]

Hi guys....
I've been working hard on my 64 s.side, (pics forthcoming). It's got a stk 305. I installed a new radiator and electric fan along with the fan wiring kit (non adjustable). The kit has the fan switch that screws in the head/intake. My intake has no provision for installing the switch in the intake and I have the sensor for my mechanical autometer temp gauge in the driver front head so I installed the fan switch in the rt rear head. The switch temp range is on at 200deg and off at 180 deg. The fan comes on right at 200 but wouldn't turn off. After about an hr trying to figure what's wrong, I realized when I did intake gaskets a few months ago that I put in a 190 or 195 thermostat....there's the problem. My 1st thought is to put in a 180 thermostat but I wonder if the fan switch being that far away from the thermostat housing will not see 180 deg coolant as it travels through the engine.
So, thermostat or adjustable fan control?

[PGSigns]

With the 195 thermostat it will never cut off and with a 180 the engine has to start to over heat before it will cut on. It also may need to run all the time anyway to provide enough air to keep it cool.
Jimmy

[64stpside]

Originally Posted by PGSigns

With the 195 thermostat it will never cut off and with a 180 the engine has to start to over heat before it will cut on. It also may need to run all the time anyway to provide enough air to keep it cool.
Jimmy

You don't think the engine will get to 200 deg before a 180 will re-open? I'm not sure I agree with that as it's only a 20 deg difference. I'm totally cool with it getting to 200 before the fan cuts on. As far as the fan having to run all the time to keep it cool, I guess I should have stated what my cooling setup is, sorry. I have a 3 core radiator and a aluminum shroud that covers the whole core area with a 16 in fan so I think I should get sufficient cooling with that setup. My issue is still if I run a 180, will the coolant temp still be 180 by the time it reaches the switch that's in the rt rear head, I just wanted opinions before I change the thermostat out.....I hate fooling with coolant

[Palf70Step]

Once your thermostat opens, it pretty much stays open. So even with a 180 thermostat, your truck is probably always going to run in the 185 range, which means your fan will probably still run all the time. Personally I would change the thermostat to 180, then see how she goes, but the head pickup might show it warmer all the time than at the intake where the sensors was set to run at, so you may want 2 options after the thermostat change:

1. Manual kill switch to cut off the fan
2. Change the senor to one with a probably a higher set of numbers, at least the shut off one be higher.