Can someone explain what this is showing

[SteveO_71]

I've read the info on the DVCV and think I understand how that operates by switching vacuum from ported to manifold depending on temp.

However, along the way, someone installed an electric DVCV in my car. The pic below shows how the electric one operates but I'm having a hard time trying to figure out what its really showing. I dont understand how the +12v comes into play for a part that is engine temp controlled.

Can anyone interpret this picture and offer an explanation of how the thing is suppose to work? I'm tempted to just replace it with a 3 port, no 12v one to make things simpler.

Thanks!

 

[mjlan]

If I am looking at that correctly, the switch used coolant temp to change the vacuum flow and close an electrical circuit.

It could be used to energize an idle solenoid at a specified coolant temp or do something else electrically at the desired coolant temp...

 

[Don C]

Are there any wires connected to it now? If not it'll probably act just like a non-electrical 3 port vacuum valve. If it does have wires connected to it, it may be part of the EGR control.

 

[SteveO_71]

Since +12 is on one of the contacts, I'm assuming its acting as some sort of temperature switch as mentioned above. The only documentation I can really find is on the 429 cougar/mustang site so maybe its only a 428/429 related item??

At any rate it doesnt look like a normal part from a 71 351 ( especially since it isnt sold anywhere ) so I can probably switch it back to the normal 3 port DVCV. Unless I can trace the wires to see where they go.

Thanks!!

 

[Don C]

The only way it would have something like that in 1971 was if it was originally a California car. Someone may have added something at some time like water or alcohol injection, to combat pinging due to the fuel that was available in the 70s and 80s, and wanted it temperature controlled.