I'm working on a motor that uses a vacuum and electrical harness from a 1986 Mercury Cougar 3.8L with EEC-IV. I have an unused vacuum line from a solenoid and I'm not sure where it goes. It's labeled as "Intake heat control valve (31)". In the description, it says it warms the heat riser in the intake manifold.
The motor does have a preheater, but it is controlled by a bimetal valve (23) attached to the main vacuum line. So I'm guessing it's a completely different system than that.
What exactly is this valve for, and what do they normally attach to? How is this system different than the other vacuum controlled preheater?