1973 - 1979 F-100 & Larger F-Series TrucksDiscuss the Dentsides Ford Truck
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I have a 1978 F250 with a 400. It has a componet in the vacuum system that I have not been able to identify. It sits next to the EGR valve. I have taken some pics and posted to this album: http://pg.photos.yahoo.com/ph/traxle...bum?.dir=/a2c2
The one I am talking about is the one that I have moved to the center in pic 002.
I also don't have a good pic of a vacuum diagram for the ported vac system.
I have looked at Million's diagrams and the ones on AutoZone. None of them seem to show my setup.
Can anybody identify this componet and point me to a vacuum diagram that tells how it (and other) ported system componet systems are routed?
The thing in photo #2 is the vacuum amp. The factory calls it a Venturi Vacuum Amplifier. It controls the EGR in relationship with Venturi vacuum. If you look at it close you will see letters printed next to each port. V will go to the venturi port on the carb. M will go to manifold vacuum. R will go to the vacuum reservoir. O goes to the EGR. If you don't have a M then you possibly have a S. The S means that it has an EGR Solenoid in line with it, although I dont see an EGR solenoid in the picture. As you can see this gets very confusing and each year and engine can be completly different. As to getting a decent vacuum diagram, good luck. I was fortunate on mine because I had a smog machine at the time and made copies of my trucks vacuum diagrams before I sold the smog station. You might make friends with a smog mech and see if he will show you his books. They were pretty complete at the time I was doing smogs. If I can be any Help I will be glad to try. Give me more info and I will try to help. Good luck
I have added a picture to the album with the VVA removed. It includes what I assume to be a solenoid but I am not sure because I am used to electrical solenoids. In the picture I have identified the different ports and what markings they have. The line that goes to the 's' port on the back of the VVA has a yellow tag. The one that goes to the 'v' port has a blue tag. The one that is marked 'o' goes to the solenoid and then to the EGR valve. The port marked 'r' goes to the resivoir. I have noted that the 'v' goes to the back of the carb (Autolite 2150). The 's' goes to a tee that goes to the carb on the choke side and to the top port on the front PVS. I don't know if the inline can shaped one way valve is in the right place. I noticed that it says 'DIST' on the white side.
I can't say for sure that this is hooked up the way it should be. I have owned the vehicle since 1981 and I had a rebuilt 400 ci engine installed by a friend in about 1989. Other than that I am the only one who has ever worked on it. I have long been bothered by some irritating problems that I attribute to vacuum routing but I never have found a good source of information so I have been living with it. The problem is that, after it warms up, it does not idle smoothly. I have also noticed that it will not kick back out of 2nd gear when I let off the accelerator after flooring it. I want to get these things smoothed out soon because I plan on selling it and I hate to take a hit on the price when the problem is so small.
In this sentence: "I don't know if the inline can shaped one way valve is in the right place. I noticed that it says 'DIST' on the white side." I mean the can-shaped, inline black and white valve that is on the blue-tagged 'v' hose.
That item that you think is the solenoid appears to be a vacuum resistor. I hate to tell you this but I don't remember anything but the 460 having a vacuum amplifier. The mount studs for the amp are on the valve cover and I don't see any. Usually the 400 has the vacuum resistor going thru a pvs. This thing seems all wrong. You are going to have to find a vacuum diagram that is specific to this vehicle. A visit to a smog mech might be in order. if I get any more info I will be glad to pass it on. Good Luck Gary
I am sure that it is a 400. As I said, I got it in 1981 with about 50,000 miles and when I got the new rebuilt engine, I insisted that he get a 400 and not a 351. It is possible that the guy who exchanged the engine got things hooked up wrong. Come to think of it, that is when I started noticing little problems. It took me a while to figure out that it was probably in the vac routing.
If it is possible to take the amplifier out of the system, I would go for that too. I just need a diagram for where everything should go to make it run right. It has a c6 transmission and a Dana 61 3:07 rear end if that helps any.
Thanks Million. We were posting at the same time. I had visited the website at "Dennis' Motorworks webpage" and looked around. I found different pics there of a 351/400 but not any schematics like the one you posted. I saw some of those on the AZ site but I couldn't figure out what was what. They didn't have any index to tell you what the abbreviations meant. I see that the other address is ford-trucks.com. I will have a look.
Well I see a LCV in the diagram but no VVA. In the pictures by 2stock it sure looks like a VVA. I suspect something is amiss. Hopefully you can correct the problem now that you have the right diagram. Thanks for the help Dennis, and good luck to you 2stock. Gary
Mine is a 7-74-R10. And the calibration specs are on the sticker I mentioned. They are in that part where it says "setting info on idle, kickdown, etc." I know enough to figure out where to set the idle and such. I just don't know how to route the LCV, VCV, VVA, and EGR. And I still don't know if I even need a VVA and, if I don't, how to route everything so that it runs better than now. There are things in the 351/400 diagram that you referenced here: http://www.clubfte.com/users/mil1ion...mDiagrams.html
that I don't have (like the air bypass valve) that hook up to the VDV. Also, I am confused about the VCV's in the diagram in your post. Is a VCV the same thing as a PVS (ported vacuum switch)? If so, the ones on my engine have only three outlets each where the ones in your drawing have 4 and 2 respectively.
Ahh, I just went looking for a confused emoticon and I realized that they are not available in the quick post. So, ....confused....
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