What is your ambient, obviously below freezing? I imagine your thermostat full open temperature is 190F. You should have 190F just below your thermostat housing. Disreguard the top tank temp in these cold climates, most of your coolant is probably running in bypass as controlled by the thermostat. You temp gun is taking a surface temp and not an internal temp reading, so I would say your 174F surface temp means your block has reached operating temperature and is running correctly. Philip.