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Unread 11-09-2013, 12:21 PM   #1
Sherms-CJ7
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Help with Carter carburetor vaccum connections

Been searching around the forum and have found allot of info, but I'm confused about what's what and where it goes/connects to on the carb.

I've got a few engine vacuum schematics, but I'm having trouble understanding what I'm looking at on the carb. I've added labels to a few pictures here so that (hopefully) one of you can help me connect the dots to figure out what's wrong with my setup and how to correct it ...

On my '82 CJ, the hose labeled A is connected to the distributor (vacuum advance?)
The hose labeled B is connected to ... labeled it on the picture as (sadly) ... I can't think of what that's called Is that the carburetor SOLE-VAC Throttle Positioner?
There was a hose connecting C to the EGR valve, which I was getting ready to properly re-route.
The connections labeled D and E were both capped off. I've actually connected E to the air-cleaner, but now I'm not sure if that's right ...

Referring to the schematic, the carb there is labeled with connection points M, M, E, and S, but which one is which?

img_3907_hose_questions.jpg

img_3908_hose_on_passenger_side_of_carb.jpg

img_3909_back_of_carb.jpg

vacuum_diagram_82_6cyl_manual_trans.jpg

Any help or guidance here would be greatly appreciated!!


John

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Unread 11-09-2013, 12:41 PM   #2
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You're going to see some inconsistencies here, and may need to do some creative connections.

For example the diagram shows the distributor advance connecting through the CTO valve (do you have a CTO?) which is drawing it's vacuum from the manifold directly.

If you don't have a CTO (not all did) you're going to need to work around it to accomplish the same basic funtionality.

Generally there are two forms of vacuum coming of the carb, full time vacuum (same as connecting to manifold) and vacuum that cuts off at idle (this is often best for spark advance).
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Unread 11-09-2013, 12:57 PM   #3
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Quote:
Originally Posted by jay-h View Post
You're going to see some inconsistencies here, and may need to do some creative connections.

For example the diagram shows the distributor advance connecting through the CTO valve (do you have a CTO?) which is drawing it's vacuum from the manifold directly.

If you don't have a CTO (not all did) you're going to need to work around it to accomplish the same basic funtionality.

Generally there are two forms of vacuum coming of the carb, full time vacuum (same as connecting to manifold) and vacuum that cuts off at idle (this is often best for spark advance).
Thanks for your help Jay!

I actually do have a CTO, but I'm missing other components such as the Vacuum Resevoir (don't think that's there) and I'm not sure about the Vacuum Switching Solenoid (SOLE-VAC) ... and, don't have an Air-Pump.


Keith460 posted this picture ...
From: http://www.jeepforum.com/forum/f8/ai...stions-864676/
webervacuumhookup1.jpg

That one confused me because of his label for the hose that connects to the TAC system ... then again, he has a Weber whereas mine is a Carter.

Grrrr ... can't believe this is such a PIA and is so confusing ...



John
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Unread 11-09-2013, 02:11 PM   #4
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Better late than never ... I found a bunch of good info here:
http://www.jeepforum.com/forum/f8/va...ypass-1047507/

Still, if anybody can help clarify what's what as far as the pictures I posted and the M, M, E, and S vacuum ports in the schematic, I would greatly appreciate it ...
It would be really cool if somebody could answer question of what B from my photo (the port seen easily in Keith460's photo) is, or what it should connect to? Aside from that, I'm thinking that A in my first picture is the E from the schematic. Then, I think D and E from my photo must coincide with M from the schematic. And, that leaves C from my photo as S on the schematic. Can someone confirm?

Wait ... hold on, I've found an answer to one question ...

choke_circuit_components.jpg

So, in my 1st picture, B was connected to the Choke Vacuum Diaphragm, which (going by the picture from the FSM) isn't right. That helps, but what the #$%@% is that B port; it doesn't seem to be in the schematic ... and I'm probably missing something.

Thanks -
John
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Unread 11-09-2013, 02:56 PM   #5
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It is not uncommon for carbs to have more vacuum connections than are used on any particular vehicle.

A vacuum reservoir is good to have but not essential.

The one labelled TAC in the above photo is essentially the 'M' connection in your other diagram (generic full time vacuum), same as 'B' in the first picture.

The diaphragm like structure attached to the choke is essentially an unloader, at high vacuum it pulls back the choke to minimize flooding.

I don't see solVac on your photo, perhaps your carb does not have one. it would be attached to the carb near where the throttle linkage attaches. It uses a vacuum and or electrical signal to increase idle speed under some circumstances (I believe the diagram is from a YJ, yours may be a bit different)

The basic truth is this. There are only two kinds of vacuum: full time vacuum and vacuum that is closed off at idle (primarily used for spark advance). As long as you have your systems hooked up to the appropriate vacuum type, it does not make a lot of difference exactly where the hookup occurs.
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Unread 11-09-2013, 03:41 PM   #6
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Quote:
Originally Posted by jay-h View Post
It is not uncommon for carbs to have more vacuum connections than are used on any particular vehicle.

A vacuum reservoir is good to have but not essential.

The one labelled TAC in the above photo is essentially the 'M' connection in your other diagram (generic full time vacuum), same as 'B' in the first picture.

The diaphragm like structure attached to the choke is essentially an unloader, at high vacuum it pulls back the choke to minimize flooding.

I don't see solVac on your photo, perhaps your carb does not have one. it would be attached to the carb near where the throttle linkage attaches. It uses a vacuum and or electrical signal to increase idle speed under some circumstances (I believe the diagram is from a YJ, yours may be a bit different)

The basic truth is this. There are only two kinds of vacuum: full time vacuum and vacuum that is closed off at idle (primarily used for spark advance). As long as you have your systems hooked up to the appropriate vacuum type, it does not make a lot of difference exactly where the hookup occurs.
Thanks a bunch Jay!!

That's a huge help and is really good info!!

Hopefully, will have all this connected tonight thanks to your input.

Best regards -
John
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Unread 11-10-2013, 07:04 AM   #7
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John,

Here's the layout that worked great for my computer-less 258.

Matt
258manifoldvaclayout.jpg

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Unread 11-10-2013, 07:51 AM   #8
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Originally Posted by Matt1981CJ7 View Post
John,

Here's the layout that worked great for my computer-less 258.

Matt
Matt,
Thank You so much again!!

I have everything connected now, but I have not gone through the whole Nutter Bypass thing ... yet. Therefore, my setup so far differs in that ...
1.) My Manifold Vacuum Port is connected to the TAC system of my air-cleaner.
2.) My Carb M-port is capped off
3.) My Carb S-port connects to CTO and (through T fitting) to canister.
4.) My Carb E-port is capped off.
5.) My distributor is connected to the CTO (middle port out of the 3 ports)


So, I still have to test drive, but it started up fine last night. I just thought I should see how it runs stock before going through Nutter Bypass. Then again, as I'm missing components such as vacuum reservoir and diverter-valve, does that mean I have to do Nutter mod?

I have a strong feeling I will be using the schematic you've provided!! So, Thanks very much once again!!

Best regards -
John
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Unread 11-10-2013, 08:01 AM   #9
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John,

I don't see a stepper motor on your Carter BBD. That indicates to me that you don't have a computer. Therefore, the Nutter bypass isn't necessary. My 1981 was the same way.

They started the computer-controlled carb and ignition some time in 1982. Some got them, some didn't that year. You appear to be one of the lucky ones without it.

The layout I posted provides manifold vac to your distributer, which many of us prefer over ported.

Matt
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Unread 11-10-2013, 08:28 AM   #10
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Quote:
Originally Posted by Sherms-CJ7 View Post
Matt,
Thank You so much again!!
.... Then again, as I'm missing components such as vacuum reservoir and diverter-valve, does that mean I have to do Nutter mod?


Best regards -
John
The reservoir merely provides a stable vacuum level for accessories (4wd lock if equipped, heater vent etc). It will have no effect on running.
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Unread 11-10-2013, 09:06 AM   #11
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Quote:
Originally Posted by Matt1981CJ7 View Post
John,

I don't see a stepper motor on your Carter BBD. That indicates to me that you don't have a computer. Therefore, the Nutter bypass isn't necessary. My 1981 was the same way.

They started the computer-controlled carb and ignition some time in 1982. Some got them, some didn't that year. You appear to be one of the lucky ones without it.

The layout I posted provides manifold vac to your distributer, which many of us prefer over ported.

Matt
Matt,

I do have some sort of electronic ignition control unit on the back part of the driver's side fender ... isn't that the computer? Wonder if I had a stepper motor in the past, but it was removed by the PO? I'm thinking that, given your input, I probably do need to make connections as in your schematic. Thanks again for all your help, despite the fact that I didn't quite get that my setup is missing a stepper motor and didn't understand what that meant, I feel like I'm getting a better understanding of the whole system. It's amazing though, I initially thought this would be easy to sort out ... but, this is like the 3rd or 4th weekend that I've been searching through the forum, the FSM, and the sprynet site before finally getting it even close to being connected properly ... and from the sounds of it, I'm not quite done yet So, just to make all this completely clear for any who end up reading this thread trying to figure out a similar setup ... no stepper-motor = make connections for Nutter bypass?

Best regards -
John
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Unread 11-10-2013, 09:09 AM   #12
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Quote:
Originally Posted by jay-h View Post
The reservoir merely provides a stable vacuum level for accessories (4wd lock if equipped, heater vent etc). It will have no effect on running.
Hey Jay,

Thanks very much for clearing that up!! I was really curious about what it, but that was one thing left out from that awesome sprynet resource: http://home.sprynet.com/~dale02/vac-res.htm

Best regards -
John
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Unread 11-10-2013, 09:26 AM   #13
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Quote:
Originally Posted by Sherms-CJ7 View Post
Matt,

I do have some sort of electronic ignition control unit on the back part of the driver's side fender ... isn't that the computer? Wonder if I had a stepper motor in the past, but it was removed by the PO? I'm thinking that, given your input, I probably do need to make connections as in your schematic. Thanks again for all your help, despite the fact that I didn't quite get that my setup is missing a stepper motor and didn't understand what that meant, I feel like I'm getting a better understanding of the whole system. It's amazing though, I initially thought this would be easy to sort out ... but, this is like the 3rd or 4th weekend that I've been searching through the forum, the FSM, and the sprynet site before finally getting it even close to being connected properly ... and from the sounds of it, I'm not quite done yet

Best regards -
John
The ICM (Ignition Control Module) on your fender is completely different from the "computer" we are talking about.

If you have a computer, it would be located behind the dash near the glovebox, but I'm pretty sure you don't.

Try the layout I posted and see what you think. Be advised, manifold vac to your dizzy will add advance to your idle and the idle speed will increase, usually around 150 RPM. Simply dial your idle back down to where you prefer. I liked mine around 700 RPM.

Matt
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Unread 11-10-2013, 09:33 AM   #14
Sherms-CJ7
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Quote:
Originally Posted by Matt1981CJ7 View Post
The ICM (Ignition Control Module) on your fender is completely different from the "computer" we are talking about.

If you have a computer, it would be located behind the dash near the glovebox, but I'm pretty sure you don't.

Try the layout I posted and see what you think. Be advised, manifold vac to your dizzy will add advance to your idle and the idle speed will increase, usually around 150 RPM. Simply dial your idle back down to where you prefer. I liked mine around 700 RPM.

Matt
Awesome - Thank You for clarifying!!

Can't Thank You enough - really! Yeah, I don't remember pulling out a computer when I did my tear-down, so you must be right that I was actually one of the lucky ones.

I will make those connections as you so clearly laid out.

Best regards -
John
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Unread 11-10-2013, 04:29 PM   #15
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Hey Matt!!

THANK YOU, Thank You, Thank You!!!!!! A thousand times Thank You for posting that schematic. Really though, Thank You to all who chimed in here to help!!

I can't remember the last time my CJ rode that smooth. There's still some sputtering ... exhaust leak, or maybe that's just always going to be there with the original Carter BBD carb. But, it seems much smoother and I no longer seem to have to back off on the accelerator when cruising to find "the sweet spot" ... know what I mean? Before, when driving in 3rd or 4th, the Jeep would at times start spitting and sputtering, so you back off on the gas until the gasping or whatever stops, but then you're not going as fast as you wanted. Anyway, forgive the ramblings; I'm just excited! I was hoping for improvement, but it really is better than expected.

Thanks again to all for all the help!!

John
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