[Jack21]

Don't confuse apples with oranges.

The Temperature sender provided by Autometer is the temp sender for your temp gauge. It does not get wired to your fan circuit.

The second temperature sender is for the cooling fan. Some fan thermostats monitor hot air as it exits the fan shroud. I prefer a t-stat that monitors the water in the block. More accurate. In my case, I drilled and tapped a second t-stat fitting in the intake right over the water jacket outlet in the head. This is a Ron Francis Wire Works fan t-stat kit.

And if both Don, and DV are expressing second thoughts over your choice of fans, I'd heed their advice. Easier to swap fans now than after car is on street (and overheating). I'm using a 16" Scotts which works fine. They swear by Spal and could give you a good price on one. The "Mutha" of the fan install is mounting the rad bracket to the frame, mounting the fan bracket to the rad, and mounting the fan to the fan bracket so it just clears the steering rack on the bottom, and just clears the hood bracket on top in the hood down position. You only want to do this once.

Theory of operation. Bat power (directly from the battery through a separate fuse or circuit breaker) goes to the control relay, then out to the fan motor on the NO (normally open) relay terminal. The fan motor can be grounded to the frame, or grounded to a grounding bar which is grounded to the battery (per previous description).

A splice on the ignition wire is then routed to the control lead on the fan relay. The only power being used on this control circuit is the magnetic coil inside the relay. The rest of the fan control is called "complete the ground".

The relay coil is energized when the magnetic coil inside the relay being powered by the ignition circuiit is grounded to the chassis or engine. This ground is completed through the fan thermostat sender. The fan sender is Normally Open sitting on the bench. When the water temperature reaches 205 deg., the contacts inside the sender close, completing the ground to the engine block, and powers on the fan from the relay. When the water temperature drops down to 180 deg, the contacts inside the sender open, the relay then opens, and the fan turns off. A fan override switch on the dash provides an alternate means of completing the ground aside from the temperature sender. A second wire can be run from the temperature sender terminal on the relay to a switch on the dash. The other terminal on the dash switch gets connected to a chassis ground. Closing or turning on the switch on the dash completes the ground, and powers on the fan from the relay.

Control relay systems like this are used when high amperage devices are being controlled by low amperage control circuits. Cooling fan is one example. Halogen headlights, high energy ignition systems, sterio amplifiers, horn, and starter are others.