temperature sending unit

[Randalla]

Well I have the gauge out and apart and don't see any way to calibrate it. It appears to be just a bi-metal strip that contracts and expands based on resistance. Pictures to come

[Randalla]

Here you go

[steve_car]

Steve, good to know. My fuel gauge works, but has a very small range. When it's full the gauge sits at 3/4 and when it's empty it shows 1/4 full. Do you know whether this is a gauge calibration issue or a sending unit issue?

You might want to pop out the sender. Then move it to both extremes while watching your gauge and see how it behaves. If the gauge still reads screwy, see what the resistance range is.
I see that you have a 67.5 gauge. I only looked at 66-67 ones. What are the holes in the back for?
The 65-67 1600 fuel, oil, and temp gauges have two adjustment wheels each. The 65 1500 fuel doesn't have any, but the oil and temp gauges also have two each.

[Randalla]

Good eyes to see the remainder of the sticky stuff. I had hoped that was where the adjustment was but it wasn't. Probably just to keep the dust out.

[Phred58]

This thread had me interested so I pulled a NOS gauge I have (67.5 temp / oil) and those slots on the back do seem to allow for adjustment. If you look at the inside of the gauge, you will notice that the metal legs with the slots in them are "pinned" in place but the holes are elongated which means they were meant to be able to move.

From what I could tell, it looks like both "legs" of each gauge (hence the four holes through the back of the housing) are adjustable. I have no idea what difference it would make adjusting say the left leg of the gauge vs. the right leg of the same gauge - someone with more mechanical knowledge than I may be able to determine that or you could just try making small adjustments to one leg at a time and check the results. I would put a reference mark on the gauge housing and also on the leg before you try adjusting it so you can return it to the original position if moving the leg has no obvious result.

[Randalla]

Update on my inaccurate temperature readings. I did a lot of experimenting to see if an in-line resistor might solve my problem. I started with a 2K resistor and worked my way down till the reading was correct. In my case the proper resistor ended up being about 50 ohms (yours may be different). I added a male and female connector to either end and shrink wrapped the three components. It ends up just being a short link (3") between the gauge and the dash harness.