Need Vac Diagram

Dano78

Founding Member
Nov 1, 1999
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Vancouver, WA
I'm in dire need of a good vacuum diagram for my '78 2.8L v6 Ghia. I've combed my Chiltons, Clymer, Haynes and Glenns as well as a factory Shop manual set for 1975 and couldn't find squat. They are all just to vauge. I'm trying to hook up the smog pump and need vacuum to work so it'll dump the injected air when decelerating. I'm thinking that maybe a Mitchell book or something may have the answers. Or any other source??:shrug:

I'd surely appreciate it. Thanks- :nice:
 
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I looked in my '77 electrical/vacuum schematic book, but there was nothing there regarding emissions, just the other vacuum systems. The shop manual set (also '77) has some info in Vol 2 regarding the thermactor system, but no real vacuum diagram to speak of. From what I can tell just quickly looking it over, the bypass valve is supplied vacuum from the intake manifold, and uses the sudden drop in vacuum to dump the air pump supply. It appears that there are 2 basic types of bypass valves, a vac differential valve, and a "regular bypass valve. It appears the vdv type simply uses a delay valve, whereas the "regular" valve uses a retard delay valve, along with a rather elaborate vacuum circuit. I'm not familiar with what is on the 2.8, so I'm no help there.

We had a mishap with the scanner power supply, but I might be able to take a digi pic of the appropriate pages if you don't have them.
 
Mark- Yeah we do but its a rotating 25 years or older. The Ghia is exempt but I'm gambling on a possible buyer from Oregon too. Oregon's emissions is froze at '76. If i didn't having all the goodies to put the system back together, I would waste my time. But depending on the buyer and the fact that I'd like to learn how this junk worked and to troubleshoot it a bit. :shrug:

Cobraman- Yeah like I was saying, even in all my other books it is very vauge. I don't understand why they'd be vauge or leave that stuff out of even the factory shop manuals. if you could try to get pics of those pages, we;l see if they are usable. The bypass valve (from my understanding what is called the bypass valve is the larger soda can sized unit inbetween the air pump and the steel tube assembly that injects the air)on my V6s has two vacuum nipples, requiring two vacuum sources. I do have the VDV valve (a saucer shape smaller unit that has in and out nipples) aswell, which does come off of one of the two nipples on the bypass valve. And then off of that is a smaller fuel filter looking plastic unit connected after the VDV. (i assume this is a one-way check valve)
I just have no idea where to pull the vacuum sources for this thing. If it goes into "bypass" full time, who cares. Just as long as the main hoses are hooked up and that pump's turnin.

Also, on this same rig, the charcoal canister has two lines that run into the engine. One from as much as I can tell goes to the 2nd smapper nipple on the PCV valve and am i right by assuming the other line goes to the nipple on the top of the float bowl of the carb? If not, where? (I would think it'd be the same for the V8 too)

Thanks alot for your time, I really do appreciate it. :hail2:
 
Sounds like you have 2 mixed systems. The bypass you describe sounds like the integral diff valve version, but you also mention the seperate vdv.

This illustration shows the integral valve
http://img68.imageshack.us/img68/5875/dsc018344fk.jpg

This is the standard bypass.
http://img114.imageshack.us/img114/1734/dsc018442dm.jpg

Layout with the seperate vdv
http://img114.imageshack.us/img114/2069/dsc018353xf.jpg

Snippet about delay valve
http://img145.imageshack.us/img145/1488/dsc018463bx.jpg

Corresponding illustration
http://img145.imageshack.us/img145/2913/dsc018379fu.jpg

The equipment list
http://img145.imageshack.us/img145/3347/dsc018470qm.jpg

There are other illustrations that mostly show the different modes of the bypass valve. Looks to me like the simple plan is to source one line to the manifold vac tree, and the other to the thermostatic switch on the aircleaner housing, and throw in a check valve to make it look good.

The PCV setup changed for '78, I think, but it does seem to make sense as you described. It would allow burning the stored vapor through introduction into the intake via the PCV valve. Earlier versions had one line that attached to the fuel tank vent line, and the larger paper corrugated tube ran to the air cleaner housing. They didn't "capture" fuel bowl vapor that I recall. Seems like one of the '78 302 parts cars had the bowl vent teed off into the PCV tube, but it's been a while.

I never bought the '78 manual set, guess I should have.
 
Wow, that about the best set of diagrams and info I've gotten yet! Thank you very much! :hail2:
I talked to a few of the older equip mechanics at work to see if they could shine any light on the subject. The concensus was that Ford pretty much has a one-off system each year until fuel injection came out. At that point the smog systems were all streamlined. So they all said that i pretty much have to have a '78 book to be 100% correct about things. However those pictures you sent are really, really close. I may be able to do some damage now. My last resort was to scour the library for factory vacuum manuals or if I get lucky, old mitchell manuals. Or atvery best find a super low mile V6 car that hans't been tampered with and trace and photograph the heck outta that sucker.

Anyhow, thanks again, I rally appreciate those pics and I think I'll do some expiramenting to see what it'll do. :nice:
 
Dano,
I have a 58 page Ford 1979 training manual titled "Emission Control changes for 1976-1979."
Way too much information (of which I'm certainly no expert at) to get into here, but definatly has a lot of great info that would be pertinent to this topic. While not alot of specific info in regard to the 2.8, there's more then enough general info in it to allow you to solve your problem and probably make you an expert of sorts on the systems if you are willing to study it in depth. LOTS of useful vaccum diagrams and (component internal cutaways) too!

In brief, and in addition to general EGR and Thermactor system info for all 3years, some specific areas of content for 1978 CHANGES include the following:
Thermactor System, Air bypass valve, Backfire-Supressor valve, Air Control valve, Thermactor II System, Feedback card Electronic Control System, Three Way Catalyst System, EEC Control System, Evaporative Emission SHED System.

I am not able to scan or photo all this, but I can obtain and send you hard copies of the pages if you like within a day or two. Send me an email with your address if you are interested. Mike
 
Yes I agree 100%. There hasn't been too many topics where any number of us couldn't come up with good answers or resloutions. Lots of knowlege and resources between all of us.
An speaking of which, I have here in my hand, a Mitchell Manuals titled"1975-82 Vacuum Circuits Domestic Cars and Light Trucks"! One of the elder mechanics brought it in today. Appearantly the shop had a bunch of books like these and they had tossed them out. Well, he grabbed a bunch of them and rat-holed them in his basment. It is LOADED with vacuum diagrams! THe really funny thing is that all the Ford diagrams in '75 are drawn out schematics while the '76-'78 are pictures of the engine with arrows pointing to the components. THe '79-'82 are back to drawn schematics. :shrug: This may be why vacuum diagrams are non-existant after '75 because these pictures are kinda hard to read. But this book shows stuff for AMC, Chrysler, GM, Ford, and Jeep too.
So between this book and Cobraman's schematic, I should be in good :nice: shape. That is unless I'm missing some parts.... :(

LXXVICOBRA- I'd still be interested in those pages if you're willing. Most people read magazines on the crapper, I read manuals and tech books. (The crapper is about the only place I get any real reading done. :D ) I suppose I'm some sort of info junky or something. I dunno. But yeah, you bet I'd be interested and I'll flip you an e-mail.
 
Just wanted to let you all know I got'er functioning... at least I think so. I had enough spare parts from 6 different V6s to get all the right pieces that I needed. Boy it'd be alot easier if all those temp controlled valves, check valves, VDV and and so on were still available. :rolleyes:

But it's not popping through the exhaust like it was. It does just a teeny bit but it's hardly noticabe and probably because I hollowed out the catylatic converter. (it was pretty plugged) I'm not so sold on how they were going about what they were doing with all that vacuum crap, but after dealing with it and racking my brain with all those pictures, diagrams, and articles I have a much better understanding of what they were trying to accomplish with those systems. You could just about label it as a vacuum operated 'computer' if you will. After you start figuring it all out, you have to admire the nutbags that designed these systems! :crazy:

Anyways, thanks again, guys.:nice:
 
No, sure don't. Newest I have in front of me covers up to '82. The vacuum setups in the foxes ahve to be 10x easier than the 70's Mustang IIs. Have you looking in a Chiltons, Haynes, or other shop manual? Try looking in a Mitchell maunal too. :nice:
 
Dano78 said:
I'm in dire need of a good vacuum diagram for my '78 2.8L v6 Ghia. I've combed my Chiltons, Clymer, Haynes and Glenns as well as a factory Shop manual set for 1975 and couldn't find squat. They are all just to vauge. I'm trying to hook up the smog pump and need vacuum to work so it'll dump the injected air when decelerating. I'm thinking that maybe a Mitchell book or something may have the answers. Or any other source??:shrug:

I'd surely appreciate it. Thanks- :nice:


Dano78 try this:
http://www.hampys.com/MII/images/IMG_1421b.jpg <-- Vac Diagram for 4cyl
Chad