1940 for temp gage

[flathead 53]

my 40 coupe runs at 160-170 degrees on a 90 deg day, temp gage goes all the way to hot, changed gage to brand new NOS gage,and NOS temp sender two pole type. gage doesn't work at all. installed my old single pole temp sender. after running about ten minutes it goes all the way to hot, I'm thinking it has to be the sender , not sure why the two pole sender did not work, again i check the engine with inferred temp gun still running at 160-170 ,