Hi all! This is my first post as I tear into my new-to-me '73 F100 Custom with the 302 and auto and I'm already overwhelmed by the wealth of knowledge just by reading!

The truck runs okay but the vacuum system has been hacked and moved around all sorts of ways, so I'm trying to get my bearings and get it as close to factory as I can, within reason. I bought the Engine and Emissions Factory Manual off of eBay and, upon looking at the diagram, noticed that my truck doesn't seem to have the PVS (DVCV?) valve with the three stems coming off of it. There is what appears to be the Temperature Controlled Vacuum Valve with the two stems, but no PVS. The factory manual shows two diagrams, one for AC and one for non-AC (me) and both show the PVS but only the AC diagram shows the Temperature Controlled Valve (which I have). I couldn't spot a place for the PSV or any indication that it was ever there, but the manual says that it is, "always present." So, really, I have two questions:

1) Is it normal to not have the PSV? Are there variations to the vacuum system that the factory manual isn't showing or am I missing something? I've heard of people with Mustangs not having a PSV, so would the same be true here?

2) If the PVS system isn't supposed to be there, what's the best way to route the vacuum lines as if it were bypassed?

Any help is appreciated, thanks so much!

 

I hate to see a thread asking for help just lie there, even if I don't have anything helpful to add.

You used PVS and PSV interchangeably and then added DVCV into the mix...I'm not familiar with these abbreviations. Could you clarify?

 

Not that I have much more, but here is some interesting info on the PVS stuff. https://www.ford-trucks.com/forums/1...ml#post3652727

 

PVS= Ported vacuum switch, that's those temperature controlled switches that have two or more vacuum lines going to them.

 

Some pictures of what you have would be helpful, but yes, there are variations in the emission controls systems. That's what 90% of the typical vacuum lines are for. Other than factory A/C (which you don't have) and timing advance, just about everything else vacuum is emissions related.
As a (very) general rule, the PVS will be mounted either in the thermostat housing or in the water passages at the front of the intake.

 

AhHa...I figgered it was probably some kind of vacuum-operated emissions gizmo, my brain's vacuum switch wasn't working.

My F150 is blessedly devoid of prehistoric emission-control contraptions.

 

Thanks everyone very much for your help. I'll see if I can get a picture uploaded tomorrow to help. I can't remember exactly, but whichever this is has a coolant line at the top of it. The shop manual is contradictory, so that on top of my lack of emissions know how leaves me scratchin my head at some of this. I've got a new purge solenoid on order and now I've also got to put in the temp gauge sender switch the PO took out of the intake manifold AND figure out what goes in this mystery hole on the front of the block, driver's side. It's what I get buying a farm truck with a lot of "that'll do" reengineering in it.

 

I think you'll find, like most of us have, that one of the worst things that could happen to our trucks is a "previous owner".

 

TYPE 2 = C8AZ-12A091-A

 

Thanks, that's a big help! It definitely has Type 3 but not the others.