Hi everyone,
Really appreciate this website. I have had my 79 F-100 for a few months and I'm just getting around to some vacuum line questions. Namely, it's missing a few vacuum lines and want to make sure I know where to connect them. I removed the air cleaner and took some photos to illustrate:





So there there are two ports missing vacuum lines - "E" on the left and "S" on the right? The vacuum schematic I have says "S" goes to distributor and "E" goes to a tree also connected to TVS and WOT ("WOTever that is"). Can anyone verify if this is correct?

Second:




Whatchall call this, and to what should it be connected? Any help is greatly appreciated!

 

 

The item in the 2nd photo is called a ported vacuum switch (PVS). Typically it's placed in series between a ported vacuum source on the carburetor and the EGR valve. For a 2-port PVS, it doesn't matter which port goes to what.

One of the ports shown on the carburetor should be manifold vacuum; the other ported vacuum. Ported is typically positioned higher on the carburetor, but you can check with your finger. Manifold will have vacuum at idle; ported will not. Both will have vacuum as you open the throttle, and then the signal tapers off.

Ported vacuum on the carburetor typically goes to the EGR setup (see above) and/or the distributor vacuum advance, and in some cases the purge valve for evaporative emissions. Manifold vacuum on the carburetor, if used, may go to a dual-port vacuum advance. Other small-diameter loads like air cleaner door or transmission modulator are typically sourced off the vacuum tree on the firewall, even though the signal is the same.

EDIT: just refer to red's diagram (I type too slow).

 

I believe that, at idle, more gas leaks out of the "S" port than "E." There's also no open vacuum line from the distributor. It's already plugged into something else (I can take a photo and post it tomorrow).

I have the Chilton's manual, which contains the vacuum schematic. Your explanation was way more helpful - I guess I should have said I'm kind of a N00B with carbs/vacuum stuff.

 

front one goes to the pvs mine is on the bottom plug

back one goes to distributor so would need to see the pic

also just cause i knoticed the big black hose just below where the air cleaner goes
mine is missing

 

Thanks to everyone for the help! So here we go with another round of photos to suss out where these lines are supposed to go. I just moved from New Orleans back home to VA, so it's taken a few days to get back out to the truck . Dead battery and no time meant that my friends & I pushed the truck onto the auto trailer (we had some crucial help from a neighbor and his heavy-duty ratchet straps), but it was quite the workout.



Now, without further ado:



Here's the line from the distributor (sorry for the bad photos - iPhone not the best camera). It runs up and behind the block and has a little plastic piece in it as seen here:



I kind of think this T or whatever is unnecessary, since it just connects two shorter lines that I could replace with one new longer line. Anyway, after the plastic bit, the line from the distributor runs into the back of the carburetor, shown in the orange rectangle. I thought that it was supposed to connect at the smaller orange oval ("S" port) instead.



And for an extra puzzler - there's what looks like a vacuum line port on top of the air cleaner:


As I said before, I'm a bit of a novice with these lines, so I really appreciate any help and/or corrections you can offer. I'll try and dig out my Chilton's manual from the storage unit, and the truck's at an outdoor storage lot while I sort out a place to stay, so I'm trying to get over as often as I can in the hopes of driving it to the new place. Thanks!

 

I won't guarantee what I'm about to say because I haven't tried/seen it with my I6. The valve on top of the air cleaner is for that flap in the hole(opens and closes it). I was told by a mechanic buddy to just to leave it off and not worry about it.