[87Skier]

I did some searching and didn't see a temp sender I liked and didn't want to deal with machining a temp sender to fit or drilling out and tapping the other head to accept the older style temp senders, so I bought the 3 wire to do some testing.

If you are using the stock 67-72 gauge you know it doesn't have temperature marks, so I just did a best guess and decided to fit the lines to about where I wanted the normal running temperature to be. The picture below shows how I defined the temperatures. I determined the resistance at these points and plotted them.

The temp sender was heated in oil. Temperature was monitored with a candy thermometer. Resistance was checked with a multimeter.

The line denoted resistor network is adding in additional resistors to bring the gauge into calibration.

From the graph you can see that there is very little difference between the lines from 155 to 205, so this will be fairly accurate. The resistor I'm going to use is a 147 ohms (100 + 47), which produces the green line. See the diagram for connection.

The green line can be shifted up or down by changing the resistor. A 100 ohm resistor moves the line down, meaning that at 200 degrees, the gauge will see less resistance making it read hotter than if a larger resistor is used.