Temperature gauge with a LS 1 motor

[David623]

My temperature gauge barely gets off the cold mark, temperature needle should be halfway on the gauge and mine barely gets past the cold mark. I have a 1999 LS 1 and we hooked the [original 350sending unit] into the LS cylinder head we retaped the threads to accept old sending unit.
I have checked and temperature 190 degrees when warmed up, so I just don't know its not reading correct [meaning needle at halfway point]
Any help would be appreciated.