Whyzit so cold in my engine?

I recently replace the:
-waterpump with a Heisco
-thermostat with a high flow 195*
-thermostat housing with a high flow one from Heisco
-upper and lower hoses
-clutch fan
-serpentine belt.

I am now running really cool. The temp gauge never goes above exactly between the first mark and 210*. At first I thought this was good, but now I am wondering if I am not reaching proper operating temperature. My gas mileage has suffered a bit.

I suppose I should steal the meat thermometer from the kitchen, when my wife isn't looking, and take an actual reading. Should it be 195*?

I have the exact same problem.
new water pump (nothing special tho)
new thermostat 195
lower hose is new
I however took out my a/c and the condensor in front of the rad... so its getting much more air.
my milege hasn't suffered too greatly, but I wonder the same as you, if this is too cold and should I not get it back into proper temp range?
my only thought has been to put a dam of some kind in front of the rad to limit air flow...

Years ago a line mechanic told me you could put 10 identical thermostats in a pan of water with a thermometer, start heating the water and record temps where each thermostat opened; no two of the ten would open at the same time/temp. OK, so they were not so exact. Somehow I don't think that quality control has improved much since then.

Might be good to have a real number to associate with the perception of runing cooler. If you can, have someone with an infrared thermometer check when the engine is at operating temp. Or you could do the old pan of water, thermometer test.

WOW ,, XJ's usally run hot , I had to take out the 160 thermo that was in mine,(fouled my plugs)
and replace it with the 195. Now it runs near 200 all the time.,,
However,, here the temp and humidity and atmospheric pressure are Higher.

might have something to do with that "High Flow" thermo you got.