I have installed a Classic Industries OER console temp gauge and TU12 sending unit in my 69 350 and the temp gauge reads slightly below the quarter mark on the cold side. I installed the sending unit dry. I have grounded both 12 and 3 oclock posts, 3 oclock to pink 12vt and 9 oclock green to the sender. All other gauges are working as well as the lights in the cluster so I feel the grounds are good. Do I have it wired correctly or am I missing something. Thanks Dave

The only ground connection is the 6 oclock post. All others should be insulated from the metal backing plate.

Normal temperature reading on the guage at 180 degrees is a line above the 1/4 scale mark.

I'm getting close. The tech at Classic faxed me a hand written sketch that shows grounding the 12 oclock post and 6. Thanks

Unless their gauge is internally wired differently than an original thats not how its wired. If its wired the same as the originals you will burn up the coil that brings the needle back down to the cold side of the guage. On an original the outer terminal lets call it the 9 oclock position has the green wire from the sender attached to it, the 3 oclock position terminal has the power lead connected to it and there is a coil wired internally between those two terminals. This coil moves the need towards hot, as the resistance of the sender decreases as the engine gets hotter the current flow increases and the needle moves upscale. There is another coil hooked between the power terminal and the 12 oclock position that is wound in the opposite direction as the previous coil. There is an 86 ohm resistor is connected between the top terminal and the bottom terminal and the bottom (6 oclock) terminal is grounded. This is a fixed current flow circuit and it balances the other circuit so the needle can move back towards cold. If it didn't exist the needle would just go to hot and stay there.

The OER guage used to have an internal resistor built into it unlike the originals so it may be located between the 3 oclock and 12 oclock terminals, an if it is, then grounding the 12 oclock position terminal will work fine. I don't know if they still have that internal resistor or not, just make sure its there, or you'll be buying a new guage