What is this in my engine?

[Jacksonrobinson]

Hello everyone! First time square body owner and rookie mechanic.

Can anyone tell me what this sensor might be? It is located in the manifold.

I have an original 305.

Thanks for your help.

You must be registered for see images attach

 

[Goldie Driver]

Thermal vacuum switch that controls the EGR and the transmission lockup, I believe.

The one on the water neck is for the EFE valve and the thermal flapper in the inlet of the air cleaner.

 

[Neal Lind]

Coolant temp sensor looks to me

 

[Trucksareforwork]

Took me a while to figure these out on mine because one was broken.

The one circled allows vacuum through AFTER the engine coolant reaches operating temperature. Believe it runs to ported vacuum.

The one above it on the thermostat housing lets vacuum through BEFORE the engine coolant reaches operating temperature. It turns off, I believe, once the engine is warm. It is run to manifold vacuum usually.