Removing carb.. broke multiple vac hoses... Need help identifying (Picture included)

[Nate_V8]

So I was removing my 30 year old 85 GT carb to go for a rebuild (which is funny because it had E4 on the blue tag when I thought I read on here it should have read E5 being a 1985 mustang) and I ended up breaking a vac hose which I tracked down and ended up breaking 3 more hoses/Ts. I guess 30 years tends to make them a bit hard and brittle.

So I went to plumb some new line today and lost my diagram.


The green circles go together which is fine

The red circles I am not sure what they are and if they are required... One of them was not connected because the blue circle had a short hose that was blocked off with a golf T. I remember I tried reconnecting it (can't remember which one I connected it to) but when I connected it, the car idled funny and bucked like crazy when driving so I put the golf T back in haha. Now I'm just going to cap that blue circle off.

So can anyone could tell me what the red circles are and if I need them?



Thanks

[Walking-Tall]

Within your bottom red circle, is the EGR. Not certain of the upper. Looks like your green circled ones head (red-striped vacuum hose) to the steel tube near the firewall that heads to the transmission modulator, which answers my next question whether this car CFI. The your blue-circled looks like just how somebody connected them for your green circles with a T and blocked the unnecessary, which if not blocked, causes a tremendous vacuum leak, as you experienced.

Here is a 1985 (not sure if Mustang...) vacuum diagram if yours is missing:

[Nate_V8]

Thanks for the reply walking-tall

CFI? Is that not for an auto? Because this is a 5spd car (unless I misunderstood what CFI is!). The red striped hose does not go into that green connector, it goes into a metal tube behind it, completely seperate.

The green connector is supposed to be pointing to the passenger side. The Blue circle (which you now helped me discover what it was connected to) had a short hose with a golf T in it (very professional), I tried uncorking the golf T and hooking the hose up to the EGR which then it bucked and kicked so I put the golf T back in. I removed the short hose from the vac T (blue circle) when I removed the carb since I am not using it.

Judging how clean the nipple is on the top red circle, it was connected when I broke the tubes and Ts so I will reconnect it and I will put a cap on the EGR nipple (possible vac leak?) since I don't use it anyways and cap off the blue circle T.

That diagram tells me nothing. My last 85 had 2 Vac hoses as it was stripped.


Does anyone know what the valve is in the top red circle?

[Walking-Tall]

Oh, sorry, I see the metal upright tubing connected to a vacuum hose right behind your green circle on the right... looked like what goes to an automatic's modulator.

Top red circle valve... no idea. I'd call it excess weight, lol

Good luck with it.

[grabbergreen84]

I dunno, the CFI schematic which Walking-Tall posted might actually be somewhat close to your carb'ed car. I too have never seen that mini EGR valve looking thing. Neither my '82 nor my '84 had that. The diagram leads me to believe that is part of A/CL DV, A/CL bi-metal, A/CL CWM on the decal. What are those?
Those diagrams are actually pretty good, as they also indicate the general locations of the components.

The red striped hose goes to the flapper valve on the driver side header.

[haak60]

[haak60]

this is my 85 its missing the egr plate which i took off. the hose with the green stripe hooked to the egr valve

[haak60]

theres supposed to be a line between the diaphragm looking thing and the green vacuum switch screwed into the intake manifold. the egr line tees into that

[Nate_V8]

That helps a lot! Thank you!

What is that diaphram?

[WilliamCapri]

Hi Nate,

Here is the vacuum diagram for an 85 carb'd 302.



The diaphragm looking thing is marked as LCV. It is plumbed to a "T" that also joins the EGR port that then goes to the lower port on the green valve (VCV) at the back of the manifold.

[JACook]

The upper red circle is supposed to be fed by EGR vacuum once the engine is warmed up. (The bottom port
on the green thermal vacuum switch). That port on the LCV releases the vacuum from the exhaust heat riser
valve, along with the tee in the green circle. The branch of that tee would connect to the nipple on the EGR
valve.

The single port in the green circle applies EGR vacuum to the exhaust heat riser valve. It connects to the top
port of the green thermal vacuum switch.

The center port of the green thermal vacuum switch connects to the EGR vacuum port on the carburetor.

BTW, the CFI 5.0s all came with AODs, which do not have a vacuum modulator. The CFI vacuum systems are
completely different from the carbed 5.0, so disregard that diagram entirely.

[Nate_V8]

Alright

This is how I plumbed it yesterday.




There is 3 ports on the green thermal vac valve. I have the vac tubes in the pic (green and blue circles) going to 2 of 3 of the ports. The 3rd port, like you said, is not shown because I know it goes to the EGR vac port on the carb.

I capped the EGR because something is wrong with it as the car bucks and kicks when plugged in.

[JACook]

Where are you connecting the EGR vacuum on the carb? The 4180C has two timed vacuum ports.
The long thin nipple on the front of the baseplate is for the distributor vacuum advance, and the bent
nipple just above and ahead of the choke unit is for EGR. You would not want to get those two mixed
up.

Your blue connection to the thermal vacuum switch should be on the bottom port, not the center. The
center port is where the EGR vacuum source connects.

In addition to EGR and the heat riser, this system also controls the upstream/downstream air injection,
and vapor canister purge. So if the EGR is causing surge, you could cap it at the EGR valve end, but
still keep the other stuff working.

All of this stuff is connected and functional on my '85 Hatch, and I never get any part-throttle surge.
But multiple systems are interacting here, and for it to all come together, they all have to be doing
what they're supposed to be doing. Chances are, disconnecting the EGR is masking something else
that's not right, such as the vacuum advance system for example.

[Nate_V8]

Well I don't have the carb, I'll get it saturday and then I will take a picture to make sure everything is correct. Maybe there is a problem with the vac advance.

So with the green thermal vacuum switch, it matters which level it connects to? I didn't think each level would open up at different intervals as that strikes me as an advanced valve and that green valve doesn't look that advanced haha. I will switch them though, no problem. Can you confirm each port opens seperately?

In the picture I tried to show that I capped the EGR (white X) and used the T for the red circle. Is that ok that I plugged the red circle to where the green striped EGR tube was? I deleted the EGR hose so I figured the valve with the red circle could use that T. Pardon my advanced "red circle valve" tech lingo.

Yes I didn't show the EGR vac hose as I know it goes to the bent nipple on top of carb in front of the choke as you said.
As long as the front of the plate vac advance is connected and follows to the distributor, shouldn't the vac advance work? Is it possible a 30 year old EGR valve is doing something it shouldn't be to make it buck instead?

My last 85 was stripped down so I never had to deal with these problems.

As you can see...

[grabbergreen84]

You can test the vacuum advance by seeing if it holds vacuum. If not, it's toast. If you hit a good one with an independent vacuum, with the engine idling, you should be able to hear the difference in the engine noise.

I think the EGR valve just needs to seal up when closed, and open when vacuumed.

[Nate_V8]

After looking at that diagram in post #10, I need to switch 2 hoses, that diagram really helps!

This may be a dumb question but how do I test the vac advance to see if it holds vac?

What do you mean if I hit a good one with an independant vacuum?

[grabbergreen84]

I've always just simply pulled the vacuum advance line from the carb, and sucked on it with my mouth, like it was a large Coke from McDonalds.
If it never stops giving you fresh air, then the diaphragm is torn. But if you can only hit on it for a second before it stops giving you air, then the diaphragm is OK, and the assembly should advance your timing.
If the vacuum advance servo is working, testing it while the engine is idling should make the sound of the engine change subtly. Or you can pull the distributor cap, and watch for movement down in the dizzy.

[JACook]

So with the green thermal vacuum switch, it matters which level it connects to? I didn't think each level would open up at different intervals as that strikes me as an advanced valve and that green valve doesn't look that advanced haha. I will switch them though, no problem. Can you confirm each port opens seperately?

The thermal vacuum switches are not all that advanced, pretty simple really. When cold, the 3-port
versions connect the center port to the top port, with the bottom port blocked. Once they reach their
specified temperature, they switch the center port to the bottom port, with the top port blocked.

So yes, it very much matters how you connect the vacuum lines to them.

The grey thermal vacuum switch with the electrical connector is for the vacuum advance system. It
should have the distributor line connected to the center port, manifold vacuum on the top port, and
distributor ported vacuum on the bottom port. The purpose of all that is to keep the idle elevated
after the choke has opened, but before the engine is up to operating temperature. Once the coolant
reaches 160F, it switches the distributor to normal ported vacuum instead.

[Nate_V8]

Ok, sounds easy enough to check the diaphram.

JACook I switched VAC hoses to match the chart and capped the EGR, I'm deleting the EGR/smog pump anyways when i install the complete exhaust system on it.


But now I have a new problem. My carb primary bowl accel pump bolts apparently were helicolied at one point and they are stripped so I need a new primary bowl now. Now for my question, holley doesn't make an exact replacement now, the only replacement eliminates the front EGR tube (I think it is the EGR tube). What would happen if I eliminate that vac tube?

See pictures below

The big tube on the front gets eliminated, I think it is for the EGR. What exactly does this do? Does it just vent the gas fumes in bowl?


replacement part (no adjustable float but I'm not too concerned)

[WilliamCapri]

Yes, the big tube on your original bowl is the vent to send fumes to the charcoal canisters.

The valves to allow the fumes to go to the canisters are shut when the engine is running, open when the engine is off.

Not sure I like the idea of a non-adjustable float. Make sure the accel port aligns with the port in the metering block.

I'd try to resurrect the original. Either drill out the old threads and tap for a larger screw or seal with JB Weld and drill and tap. But I'm an originalist.

[Nate_V8]

Here is the picture, can't see too well. I'll see what I can do, I didn't think about JB weld. Would that be strong enough?

[JACook]

Those holes don't look large enough to have been helicoiled, maybe the threads were just pulled, which kinda
resembles a coil when you unwrap them from the screw. Dunno, but if they were helicoiled, you might could
still epoxy another coil in. Those screws really don't need to be super tight, as long as the accelerator pump
cover is flat.

I also would not want to use one of those newer bowls that have only the internal float adjustment. Bowl level
is an important tool to fine tune off-idle transition. It sets the timing of when the main circuit starts to deliver
fuel.

The bowl vent tubes are also beneficial, because they route vapors down to the canister, instead of having the
vapors collecting inside the air cleaner. This helps with hot starts. It's not a killer if you lose them, but they
are nice to have.

[Nate_V8]

That's ok, I figured out an easier way. With the accel pump plate installed, 2 screws would hold snug, 1 felt like only 1 thread was in and the other just spun. I noticed that the screws didn't go to the bottom because with the accel pump plate removed, the screws could screw all the way in and all of them held fine. I went to the local bolts store and picked up 1/2" allen head screws with the same thread and some lock washers and that wokred perfect! All of them completely snug and only cost $10 (minimum charge).

I swapped the primaries to 64s. Going to try that out, if i don't notice a difference, but the mileage drops noticeable, I will try out 63s.

[Nate_V8]

So I was putting the carb back on the car today and hooked all Vac hoses back up.

So I was checking the Vac advance hose and pulled the hose off the Vac tree and sucked on it (car off) and couldn't get air so I guess that means it is fine. But my problem is I am pretty sure the hose on the distributor should not just go into the Vac tree on the firewall (has the brake booster and manifold connected to the same tree). Wouldn't that mean it is getting full advance all the time??. It also isn't stock hose, it is using replacement vac/washer hose.

Where does the Vac advance hose go?? There are no capped Ts that I can see so I am lost.

[Nate_V8]

I keep replying to myself haha

I figured out the vac advance and ported vac valve by using the diagram (thanks again WillaimCapri). The vac advance was all wrong. The vac advance was plugged into the Vac tree on the firewall where the brake booster attaches to and the ported vac valve on the carb was attached to the middle port of the VCV (with the electronic connector on top) and the bottom port just had an broken hose on it. So I plugged the ported carb vac port to the bottom of the VCV (with the electronic connector) and the vac advance to the middle port. All good!!

But this part I cannot figure out and I will post pics

I will circle the area on the diagram. The hose was attached to a nipple on the bottom of the air cleaner. In the diagram the hose looks like it dead ends.

I circled the the areas in question. The diagram is crystal clear on everything except this hose. It connects to the manifold vac valve and into the T just below the huge vac line that goes to the vac tree on the firewall for the brake booster.



I circled where it conncts to the Manifold Vac valve. Where does the other end connect to?? Like I said, it was connected to a nipple on the bottom of the air cleaner