I have 3 pics posted below and I have some questions about which parts are which and what they do. Please enlighten me. I'd like to get rid of some vacuum lines that are not doing much. Some are just dangling, some are plugged. I know the EGR diminishes NOX fumes, and I'd like to keep it working, but I want to get rid of that filter box (#5 in pics)
1980 4.9L inline 6 engine.

Part# and Description:
1) Vacuum port to carb with big hose which comes from #5 plastic filter box. Can this be plugged/removed?

2) vacuum switch mounted to water pump. A vac. hose comes from egr to this and then to some other little plastic check valves and then splits off and joins carb and another plugged line

3) EGR valve. Is this where it sucks exhaust air INTO the combustion process again? What should this connect to?

4) Oil fill breather hose: Can this be removed/plugged?

5) Plastic filter box with hose going to #1 big vac port on carb. Can it be removed?

6) Rear valve cover breather hose. Removed/plugged?


http://img.photobucket.com/albums/v1...og/vacuum1.jpg
http://img.photobucket.com/albums/v1.../filterbox.jpg
http://img.photobucket.com/albums/v1...og/vacuum2.jpg

 

This line is the vent for the fuel bowel in the carb. The fuel bowel in the carb works exactly like the water tank on your toilet. So to let the fuel in the bowel, you have to let the air out. In the old days this line was made so it came up in the center of the aircleaner. Now, they want to capture these gas fumes so they do not go into the atomosphere. So they run the vent down the large hose to box #5, which is the charcoal canister, which stores the fumes.
I have experimented with plugging this line. You can, but I noticed on the car I was working on, it made it hard to start in the summertime. It was like the engine was flooded if it was hot, and I went into the store and came out to re-start it. I unplugged this line, and that problem went away, but then another problem came up. When you hit the brakes hard, fuel will slosh out of this port, and drip on the manifold. So my recommedation is to leave it alone.

This vacuum switch only allows vacuum to pass when the engine is above about 100 degrees. The vacuum source for this switch is a ported vacuum source on the carb. A ported vacuum source only has vacuum when the engine is revved up.
The whole engine air to fuel is tuned around the egr operation. But there are certain times you cannot let the egr work. You cannot let the egr work at idle, or the engine will idle rough and stall. So this is why the switch is hooked to a ported vacuum source. You also cannot let the egr work when the engine is cold. This is why the switch is there, to block the vacuum to the egr till the engine warms up. You need this switch if you are going to use the egr. And you need the egr if you are going to use this original carb.

The large round thing on the egr is the diaphram that opens and closes the egr valve. The egr valve lets exhaust into the intake, but it does it under the valve. If you take the valve off, you can see what's going on. So the vacuum lines, and thermal switch are the "control" circuit for the egr. No exhaust gases run in the vacuum lines. While the engine is idling, you can take your fingers and press up underneath the diaphram of the egr, and the engine should run rough and may stall out.

No. This would let dirty air into the engine. The PCV valve is putting a suction on the insides of the engine.

You can, but it has consequences like everything else. This is the charcoal canister. Like I said before, this stores gas fumes from the carb. You will also see a line coming up from the frame rail. This is the breather line from the gas tank(s). Just like the carb has to breath, the gas tanks have to breath too. In the old days they had a vented gas cap, and let the fumes out into the air. Now, they capture these too. If you take #5 box out, you will have to leave the line coming from the gas tanks open, or the gas tank will not get any air. You also may get a gas smell from this, as it does come from the tank. I would leave it there. There should be a smaller line coming up, and possibly tying into the ported vacuum line that goes to the carb, and serves the egr(this may be the tee you where talking about). They usually have a vacuum line running to the charcoal canister(#5 box) so the engine can suck the gas fumes out when it's running.

This is your PCV valve. It puts a suction on the inside of the engine, to suck all the bad water vapors and junk out of the engine, making the engine last much longer. It brings air into the engine through a filter and #4

 

The diagram in the link below looks like the one for your truck.

http://www.autozone.com/images/cds/g...3d800ce64c.gif

Go to the link below if you want to figure out what all the abbreviations mean in the diagram.

http://www.autoglossary.com/

 

Dave.
Thanks.
Very good information.

To clear it up, the air goes IN through #4 (oil fill) after first passing through the air filter and then it runs the length of the valve cover and comes out #6 (pcv)?

On #6 (pcv) there are 2 places for vacuum lines. Do both of them need lines run to the carb?

I traced the breather lines back to both gas tanks. I thought maybe they were vacuum lines to help the gas gauge or something, but after disconnecting them, and finding the gauges still working, I realized that wasn't it. I'll leave them and the #1 Fuel bowl vent in place to that charcoal canister.

Would anyone happen to have a picture of any of these in the correct working order?

Basically, it looks like I need the following:
1) vacuum from egr port on carb to #2 (on water pump) to the port on the round part of the egr valve.

2) vacuum from carb to # 6 PCV (but there's two ports on PCV)...?

3) Vacuum line from carb to distributor advance

4) rubber air line from air cleaner housing to oil filler cap.

5) vac lines to dash climate control pieces and power brake cylinder.

That sound about right?

You said something about not needing the EGR if I used another carbureutor. Which type carb would I be able to put on and what all would that eliminate?

thanks much.

 

Yes, that's correct.

The small nipple on the PCV valve. Are you sure it's open? A lot of times the store will sell you one of these that have both of these ports, but the little one is plugged with plastic and you take a knife and open the end up only if you need it.

Yes, you could get an older late 60's early 70's style carb for a 240 or 300. It would not have any of this stuff on it. And it would be calibrated to work with no egr. I would always keep the PCV system, it's a good thing for the life of your engine. But everything else would go.

You could also get a 4 bbl manifold and a little 390 cfm holley and put it on there. It would not be cheap, but it would eliminate everything too. If you do a search in the six cylinder forum, you may find some guys in there that have done the 4 bbl swap.

 

You're correct. After checking, the upper nipple on the PCV valve is sealed.
I'll figure out some way to fix the hose from the air filter to the oil fill cap so that only clean air gets in there.
If that got clogged up, is that what causes "blow-by?"

I found the posts you spoke of. New 4bbl carb, intake & exhaust manifolds, and some other little stuff. I think I'll approach that when the engine needs to be rebuilt and i'll do it all at once someday in the future.

For now, I have a couple more questions about the vac lines:

1) There are multiple vac lines on the carb. Some on the upper part, some on the bottom. What's the difference? I ask because i'm certain I didn't get all the lines back exactly where I got them from originally.
The diagram link posted previously is great, but I don't know which nipple on the carb to attach things to.

2) Is that temp valve (#2 in pics) on the h2o pump directional? Right now I have a vac line from passenger side of carb to that valve and then going directly to the nipple on the EGR valve. Does it need to flow in a certain direction?

Once I get all this straight, i'm going to put together a section on my website with diagrams and pictures and explanations for other folks like myself who don't quite know how all the stuff works that's run by vacuum under the hood. So any help getting this right will go a long way.

 

If you want to see something really scary. Take a look at my gallery. Your smog stuff is simple compared to mine. And mine is only one year newer than yours. :S Although I do live in California where all the stuff has to work etc..

https://www.ford-trucks.com/user_gal...&albumid=11082

To answer question one. If you look at the diagram that franklin2 supplied, you will see the carb and egr valve etc. The nipples on the diagram carb, corespond to the vacuume nipples on the actual carb, Left to right going clockwise. The "S" nipple is the first nipple on the right side of the carb nearest to the EGR valve. Then the second nipple "E" is the second from the left. The WOT is the next one on the other side of the Carb, and the BV nipple or (bowl Vent the huge one you mentioned. Labeled #1 in your Picture) is in front.

Answer to question 2: Yes the ported Vaccume switch can be directional depending on application. If you look at Franklin2's diagram again. Look for the item labeled VCV. It's on the diagram first from left, right up front. You will see the picture of the switch has a smaller end on it. That represents the top of the switch. Hook the lines accordingly. According to the diagram, the EGR hooks to the bottom nipple.

Hope that helps.

Also I'd like to mention, if your truck had air conditioning at one time, The controls is vacuume assisted and that the heater controls require engine vaccume to operate, the heat blend door, and the vent floor defrost doors to move heat to the desired location. Even if the truck doesn't have a working air conditioner.

Hope this helps.

 

I redid all my vacuum lines some years back. I cleaned it up nicely by installing two conduits for all that rubber. Each is one inch PVC painted gray. One runs from the front of the valve cover to the rear of the valve cover. It picks up the hoses going fron the water pump area to the carb area. The other is across the back. It picks up those same hoses going to the carb, plus those on the firewall area.

 

One thing you can do also is pull these lines and check them while the engine is running, now that you know whats going on.

For the vacuum line between the carb and the water/temp switch, pull it off while the engine is idling. There should be no vacuum. Rev the engine, there should be vacuum.

For the vacuum line between the temp switch and the egr valve, pull this line when you first start the truck in the morning. There should be no vacuum when you rev the engine. Let it warm up, and then pull the line again. Rev the engine, and there should be vacuum.

You can put a fancy chrome breather on your oil fill if you want. Just so it has the filter made into it.

Blowby is caused by worn rings. Every engine has a little bit, that progressively gets worse as the engine gets older. More and more pressure goes by the rings and ends up in the crankcase. The PCV valve will suck this out, until it gets overwhelmed. Once it starts getting too much for it to handle, you will start to see a little bit of smoke coming out of the incoming air filter/fitting for the PCV system. But it can get a lot worse before it finally gets to be a problem.

 

Thanks guys.
Great explanations. 81-f150, your poor truck looks like someone spilled black spaghetti in there. Sheesh, glad i don't have that man, i'd never get it straight.

You've given me enough knowledge to make sure everything is hooked up right.
It'll take a couple days to get to it (got a test this week) but I'll run all those tests, hot and cold, and get it straightened out and then probably come back with questions about the anti-stall switch. I'll probably get a smaller air filter also, cause this big fat one is just kinda taking up toooooo much space.

Looks like i'll have the following working:
1) vacuum to distributor
2) vacuum to brake booster and climate control
3) vacuum to EGR by way of temp switch on water pump
4) vacuum to PVC valve for the head
5) breather hose for gas float and gas tanks
6) circuit for exhaust manifold heater chamber to carb and back

Will let you know how it goes. Thanks so much for all the help.
This will be a great writeup when i'm done.