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Unread 11-20-2008, 07:06 PM   #1
NTL1991
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1991 XJ Cherokee 
 
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1979 AMC 258ci Vacuum Questions

Hello, I'm new here and I think this site would be the best for my question about vacuum lines for a 1979 258ci engine.

In auto shop at school we have a 1979 AMC Concord with the 258ci and the Carter BBD carb. It has 50K original miles on it. The car was donated along with another 1979 Concord to the school for use, and now only one Concord is left... Someone, unfortunately, messed with the vacuum lines and nearly disconnected all of them... I have found various vacuum diagrams online and I have ordered the 1979 AMC Technical Service Manual and I'm waiting for it to arrive... I plan on purchasing this car ($350) once its up and running but I need some help getting the vacuum lines right before I fire it up.

I have most of the vacuum lines connected to where I think they should be including all of the lines to the charcoal canister, I connected the stubby vacuum hoses and metal lines to the CTO under the intake manifold, the lines to the distributor from the Non-Linear valve. (I think it's the non-linear valve)

Is the non-linear valve a plastic bowl with a metal cap with three vacuum nipples coming out of the bottom of it? The valve is about an inch or so in size. If so, all three of those lines are correctly attached.

What I don't understand is:

1) The "Thermal Vacuum Switch" inside the air cleaner assembly that connects to the CTO under the intake manifold and to the EGR valve. Where is it located?
2) To the right of the PCV filter in the air cleaner assembly (if your looking at it installed in the engine bay) there's a hole with a little notch in it. Does anything go here? I thought the Non-Linear valve fit in here, but it doesn't. It's zip-tied to other lines/cables behind the air cleaner.
3) The air pump diverter valve has a vacuum line coming off the side of it but it's only about 4 inches long and it ends. I believe I need a tee here to connect to another vacuum line (maybe coming off the carb?)
4) Inside the air cleaner assembly at the bottom there is the TAC switch with a fitting inside the air cleaner. Does this connect to anything? On the bottom side there is one nipple that connects to the vacuum motor on the front of the air cleaner and another nipple with nothing attached. What connects here?
5) In all of the pictures of these air cleaner assemblies, I see two delay valves on the vacuum lines attached to the air cleaner. There aren't any attached on the cleaner. Are these needed for proper operation of the vacuum motor or will it be OK without them?
6) The car has an Automatic Transmission. Are there any vacuum lines going to the transmission to set shift points or kickdown or anything like that?
7) On the bottom right of the carburetor (installed on the engine, looking at it straight ahead) there is a vacuum fitting. There is an orange (newer) vacuum hose connected to it (about 4 inches long) but the line doesn't go anywhere. Should this fitting be capped off?

Sorry for all of the questions, especially on my first post. I would appreciate any help I could get.

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Unread 11-21-2008, 04:35 PM   #2
ctm
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1990 YJ Wrangler 
 
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here's a bunch of links I found, not concord specific , but some Eagle and CJ.

http://forums.amceaglenest.com/index...pic=8109.0;all

http://www.n0kfb.org/homepage/amc/te...agleVacDia.gif

http://www.n0kfb.org/homepage/amc/te...VacDia3_54.gif

http://www.jedi.com/obiwan/jeep/misc/vacuumhoses.html

http://home.sprynet.com/~dale02/list.htm
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Unread 11-21-2008, 06:21 PM   #3
NTL1991
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Thanks for the reply. I've used some of those already, and I've confirmed that I am in fact missing the Temperature-Controlled Vacuum Switch in the Air Cleaner.

I've also noticed a metal vacuum line that is directly behind the carburetor and has a metal bracket holding it in place. It drops down under the intake manifold, but I can't see where it goes from there. Could this be the transmission vacuum line? If so, would I connect manifold or ported vacuum to it?

Nick
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Unread 11-22-2008, 05:55 PM   #4
ctm
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try these autozone repair guides too.....this may be something related to what you are talking about, figure 2 shows some kind of line going down under the manifold

http://www.autozone.com/az/cds/en_us...rInfoPages.htm
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Unread 12-07-2008, 08:03 PM   #5
NTL1991
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Thanks for the guides. I now have the service manual which has been of great help too, but I have one vacuum fitting I cannot find any information on...

On the back of the BBD carburetor, above the choke plate, there is a hole on the inside and a nipple on the outside (back) of the carburetor... This is at the very top right in the middle. Where does this connect to?

Thanks,
Nick
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Unread 12-07-2008, 11:42 PM   #6
Saltydawg1
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If it's above the choke plates then it isn't getting a real vacuum signal, which means it's part of the fuel vapor system. Probably a carb bowl vent and is tied into the evap canister.
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Unread 12-08-2008, 05:33 AM   #7
NTL1991
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Thanks for the reply! I had a thought that it wouldn't be a source of vacuum...

Nick
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