Vacuum System - Album on Imgur

I don't think it's correct as is and I'm lost.

I'm not sure how to hook up the carb to the system.

Number 1 in the image is not hooked up at all. I'm missing the line to SOL V (Vac Solenoid?). I don't see either VDV (Vac Delay Valve?) or V REST(?).

I could really use some help.

 

You are probably right about 1 & 2 being VCVs,, those things are located in the water jacket. But it looks like somebody partially "cleaned up the engine bay" or tried to "make it run better" by "removing all that crap" leaving you wondering "WTF is this?"

I say "partially" because your smog (aka AIR) pump is still there and the EGR valve is on the spacer plate.

What are you trying to do?

 

What am I trying to do? Good question. I'm not sure if it's best to try to put everything back in order or finish removing it.

The truck was running horribly when I bought it so I rebuilt the carb. My immediate goal is to get that properly installed so I can get the truck running again and do some tuning.

It looks like an Edelbrock 1406 with a Carter AFB name tag on it. I'm not sure what the port under the choke is for (Nothing I've Googled shows it labeled). I'm also unclear as to which of the front ports (timed vac and man. vac) I should use. Would connecting one of those directly to the distributor be correct?

Thanks for the help.

 

Yes, the "Timed Vacuum" port is generally the one that goes to the distributor, cap off the others (but make sure the PCV and power brakes are connected, those are kinda-big, almost thumb-sized hoses).

Do you know which ignition system you have? IOW is there a sandwich-sized silver/gray box on top of the front driver's side wheel cover under the hood? It's the silver box with a white label in this picture:







Alternatively, you could have a TFI module on your distributor, it's the gray module with all the colored wires right next to the SPOUT connector in this picture:

 

I have the Duraspark.

Do you have any idea about the port on the carb. by the choke? I must suck at Google because I couldn't find out what it is.

 

No, I don't; my guess would be it either has full manifold vacuum or it doesn't, e.g. it's another "timed" port (which means it doesn't have vacuum at idle). I would cap it off for the time being unless you find a use for it.

Others here may chime in, too, I'm only giving my opinion....

 

Thank you so much for all of your help. I'll just cap it for now. Should I cap the VCVs or leave them open. I really have no idea how the vacuum system works.

 

This is why I asked you what you're trying to do.

If this is the original carburetor that you started with, and the only thing you did so far is rebuild it, then I would put everything back exactly like it was and see if & how that changes the behavior/how it runs.

In general, the VCVs control high & low vacuum signals to the timing advance mechanism on the distributor; for example, increase the advance (which raises the idle speed, which draws more air through the radiator) when the engine is running warm. There are a few other uses, too, you'll need to study that diagram on your radiator support and learn what is there, what you physically have at this point, and what you want to change. It looks like a lot of that stuff isn't hooked up at the moment which I can't say is going to help you... if you want, draw out on paper what you have connected to what and post a picture of it here and ask questions.

In short, change one thing at a time - in this case, the carburetor rebuild - so you know what change has what effect.

@Gary Lewis or @85lebaront2 or @LARIAT 85 or anybody else may be able to offer more....

 

Changing one thing at a time is solid advice. Sometimes I get carried away and want to change more when I know it's not right.

Tomorrow I'll draw what is connected to what and post it here.

 

I'll look tomorrow, it's 11PM here on the East Coast. 84 F-250 should be a pretty straight forward system. On question, can you read a label on either the left valve cover or in front of the radiator? If not, does your truck have a full floating rear axle? that will tell if it is under or over 8500 GVW.

 

Ditto on that. I have the 8600 GVW VIN code G (2 bbl carb). It has the Duraspark II ignition and is non-catalyst. If that's the same as yours, I can look mine over and get back to you. Might be Sunday, though, before I have a few hours free during daylight hours. As requested, post the emissions calibration code from that sticker.

 

I'm following this, but don't have anything to add. You are in better hands than mine.

 

Ok, first item, on the vacuum diagram, red lines are all manifold vacuum. The original system, other than the Holley 4180 carb, looks to be intact and it appears you have the 351 HO engine.

Items in your post/picture

1 - Distributor vacuum advance control, bottom port is manifold vacuum through a restrictor (delays response for emissions), center is distributor vacuum advance, make sure it is good, not leaking. Top is manifold vacuum with no restrictor (switches at high engine temperature).

2 - EGR vacuum control, use timed vacuum port on your carb to bottom port, EGR to top port. If it has direct vacuum, it will open and stay open, and it will run like crap!

3 - air BPV, looks to be correctly hooked up as long as it has manifold vacuum to the port.

Sol V, was connected to a throttle kicker, to hold the throttle open slightly, probably during deceleration or with the AC on.

EGR, check the plate, valve and manifold to plate gasket for leaks. Make sure you have the correct gasket between the plate and manifold.

Set timing per the label value with the vacuum advance line disconnected and plugged. The nipple on the front of the plate, if it is not connected then either cap it, or replace it with a plug.

Port on side of choke, if Gary Lewis can't identify it, I have no clue, I don't have an Carter (Edelbrock) carb, every thing I own is EFI now and mine had a Holley 4180 before then.

The bowl vent (large top side port), if you can't hook it to the original evaporative system, cap it or you will be rich at part/WO throttle.

Good luck with it!

 

Thank you all for the information and help.

It is 8600 GVWR and here is the full sticker https://i.imgur.com/SUdRfDx.jpg?1

I installed the carb and put everything back the way I found it. It runs the same or possibly a little worse. I can't get above 12cm Hg on the manifold port under the cowl (Is that the correct place to take a reading?)

I didn't draw the connections yet. I do know the EGR Vacuum Control is getting full manifold vacuum. Also the bowl vent was capped with a piece of hose with what appears to be a cigarette filter stuffed inside (I guess PO thought it was an intake).

I'm going to head out and buy some hose and plugs. I'll be back in a bit. Thanks again for all the help. I love you guys.

 

EGR vacuum control needs timed vacuum, the only ones that get full manifold vacuum are the computer controlled systems. They have manifold vacuum to the control valve and the EEC regulates how much is delivered. Disconnect it for now, it will never run right with the EGR open all the time.