there are two thermostat housing sensor. one is big and the other small. the small one is broken. what are they? what do they do? i'm assuming one goes to my temp gauge and the other to my choke? 4bbl 305.

 

Tvs check RockAuto.com
Thermostatic vacuum switch

 

https://www.rockauto.com/en/catalog/...um+switch,4604

 

One of them is the coolant temp sensor for the ECM. It has wires. Its function is largely self-explanatory.

The other is the TVS for the EFE valve (heat riser). It has vacuum lines. It sends vacuum to the valve, which is between the pass side exh manifold and the Y-pipe, to close it when the temp is below warmed up, to send exhaust over the top of the motor and warm up the intake, so that it doesn't run like it's cold for as long.

Neither is directly related to the choke. The choke is electric and has no external controls, other than the relay that sends it power.

 

OK....it's the coolant temp switch that's broken. that's why it doesn't idle down.

thanks!

 

It's not a coolant temp "switch"; it's the Coolant Temp SENSOR.

Get one that comes with a new wiring pigtail. (most do, AFAIK) DO NOT use crimp connectors on the wires, solder them and heat-shrink and tape them.

Probably doesn't have anything to do with "idle down"; but if it's fornicated, might as well straighten it out anyway. Eliminate one out of however many defects your situation has in effect at the same time. MUCH eeeeeeezier to troubleshoot things that have fewer individual problems simultaneously.

 

will do.... i balanced my tires and before i take it for a test spin i need to fix a bunch of little stuff like that sensor. THANKS!