If you do not trust your dash gauge, buy an lazer temp gun. They are great and take the guess work out. Just shoot it at your cap, thermostat housing, and valve covers to see what the REAL temp is.

 

Wow, those lasers are expensive! Luckily my uncle had one I could borrow...

It was dark when I tested my temperature, so I hope it's not too different during the day (which I'm sure it is, and I should test it again during the day).

My radiator cap tested out at about 185 degrees, and my thermostat housing was right around 200. My temp guage was just barely before the "H" though, but I thought 200 degrees was good? It means my 195 thermostat is opening up fine, etc. Right?

This morning I drove it in to work, and it was just barely over the "H"... (in between the two lines at the "H").

Does anybody know what temperature the guage is set too? What's the "H" actually in degrees? Anybody? It just seems to me like my guage is way off. I got a motorcraft temperature sending unit, and it works much better than the generic version (because the generic version just went way off to the right).

 

My 66 shop manual says that 180 is with the "Normal" band on the gauge. so 200 should be nearer to the H setting. you also need to know if the thermostat is really working or not. take it out and boil it and look for it to open. Lastly,put the water outlet back on without a thermostat, start the car and with your thermometer check the temperature. it should be much lower than 200 that you previously indicated in 3-4 minutes. If not, you have a serious cooling system problem that needs to be further diagnosed.