So I needed to change my temp sender and found that my gauge was always reading max at normal operating temperature.
Pretty sure its not overheating as Ive driven the car for over an hour at high revs and had no steam coming out. So i figured I would test the sender to calibrate the gauge and share the specs for everyone's benefit.
The way i did it was like this:
1) dipped the sender in an ice water bath for 5 minutes, then measured the resistance between the terminal and body with a multimeter
2) let it sit in the air for 20 minutes, then dipped it in hot water for 5 minutes
3) with the multimeter hooked up, i dipped the sender into a pot of boiling water over the stove, ensuring that the sender does not touch the pot, then waited for the multimeter reading to settle down.
Here are the results for the Minispares GTR101 sender (1970 on type)
0C - 1717 ohms
100C - 57 ohms
attached is a graph to help you guys figure out the resistance it should put out at operating temperature. I believe it should be 88C for an A+ and 85C for a standard A.
Assumption, the temperature sender resistance changes linearly with temperature (as most thermistors do)