I have a 73 big block mostly orginal, the engine and trans were rebuilt in 1994 by previous owner. The block is orginial. The drivers side head has the proper one wire temp sensor, but the passenger side has a temp sensor that is two wire, not hooked up to anything. Any ideas where this may have been previously used. Have not had valve covers off.
Mitch

Maybe something for some emission control???

I just assumed it was a replacement head, but you might be right. I have the shop manual, I'll search the electrical schematic and see if I can find such.
Mitch

Just a thought,.....
The double wire sensor may be for actuating an electric fan system, replacing the belt driven engine fan. A lot of newer systems use the electric fans. You may have later modle heads.

Not sure on BBC heads but on SBC heads, they are interchangeable, side to side. So there is a tapped hole on each head.

If it's disconnected then don't worry about it, if your curious about how GM designed it then look here:
http://www.73spot.com/index_stats_files/emission/tcs.htm

Thanks for the link, I was not aware of the 73 spot. I will spend some time there. If anyone knows of 73 specific sites let me know.
Thanks
Mitch

I bought mine new from the factory and it doesn't have the thermal switch on psgr side head.

When I installed factory A/C, I had the idle stop solenoid activate when the compressor was on to maintain the idle speed w/ the additional load. Also have vacuum advance connected to manifold vacuum. I think that was originally allowed only in 4th gear but it's been a long time ago. This is on a 4-spd L-82 coupe.

I bought mine new from the factory and it doesn't have the thermal switch on psgr side head.

Hi 73shark,
That's interesting. I just looked in the 74SM (Section 6-T) and it shows the switch in the right head. What do you have in there?

Regards,
Pete.

A pipe plug. I'll bet the switch if for auto trannies.