Part Number?

[gingerkid]

'73 280se 4.5 this is next to the water temp sensor, any idea the what it is and/or part number.

Second picture, dont need a part number but im not really sure what this knob is for... curious.

[Mike D]

Usually the knob with a white center is for rear window defrost. The sender unit is probably part of the emissions unit. Most likely a temperature sensor to activate the solenoid on the timing retard circuit. Use an ohm meter to check it cold and after the engine warms to operating temperature. It should be "open" cold and closed above about 160 degrees or so.

[gingerkid]

Hmm ok so this would affect cold idling? I had a very high cold idle speed... thats how this project started. I'll have to test this later since I'm in the middle of the project and cant run the car at the moment. thanks!