On my 1983 351 windsor there is a plastic piece threadded into the top of the thermostat housing. It has 3 vacuum ports labled "1", "D", and "2." What is it and what does it do? What vacuum lines should connect to those ports?

Where can i find a Chrome thermostat housing with the threaded port for this thing? None of the ones i see on the jegs website have this port.

-Jon

 

I found it in my "Rebuilding Small Block Ford's" book. In one section it says it is a ported vacuum switch for the egr valve. But in a different chapter it describes it as a Thermostatic Distibuter Vacuum Control Valve. Which is it? Doe sit have someting to do with the distributers vacuum advance?


-Jon

 

The problem is that there are dozens of ported vacuum switches that were used for dozens of reasons. having your calibration code would help, but I looked through one of my Ford manuals and believe I have your answers for you.

It is the Coolant Spark Control ported vacuum switch. The PVS for the EGR is usually mounted in a water passage instead of the t-stat housing. The purpose of this liuttle ******* is to regulate the vacuum advance based on engine temp. it also works in combination with the EGR valve and it's PVS, as well as a spark delay valve and a check valve.

It goes something like this:
The bottom port goes straight to manifold vacuum.
The top port goes straight to the Spark Port on the carb.
The middle port goes to a Spark Delay Valve, and then to a "T".
One side of the "T" goes straight to the vacuum advance port on the distributor.
The other side of the "T" goes through a one way check valve, and then to the top port of the EGR PVS.
The middle port on the EGR PVS goes straight to the EGR port on the carb.
The bottom port on the EGR PVS goes to the EGR valve.

Hope this helps.

Take care,
-Chris

 

That helped a little. The problem is i bought this engine and i never actually saw it in a vehicle, the PVS was on the thermostat housing but i don't know if they were using it, since all the EGR stuff has been removed. I guess I can hook up the middle port straight through the spark delay, and the into the distibuter and everything should work ok without the EGR. I'll have to see if the Ford dealer can give me a vacuum routing diagram for all of this.

I never thought i could say this but i think fuel injection is easier than this carburation stuff!

-Jon