Jeep Enthusiast Forums banner

Knox's Definitive Cater BBD (No stepper) Vacuum Line Help Thread

3K views 28 replies 7 participants last post by  KnoxButler 
#1 ·
I posted another tread on the forum, but was in to much of a rush to do a good job giving details and providing images for you guys to help me out so I'm going to give it a second shot.

Background: Im doing a bit of a restoration to my 81 CJ7, the PO messed around with it a lot and when I bought it, it was running rough at idle and at certain rpms. I fixed the idle by cleaning out the carb. idle tubes and doing a "team rush" on the distributor cap. However upon following a combination of a diagram (http://i58.photobucket.com/albums/g270/Bird-o-Prey/82Mod-1.jpg) and another thread (http://www.jeepforum.com/forum/f8/n...carburetor-vacuum-port-identification-614214/)
I tryed rerouting the vacuum lines to no avail.

The problem I ran into is that I have no or cant locate my cto valve, when I called up my local parts store they said that my jeep didn't come with one.:confused:

My goal is to get the vacuum lines routed correctly so that I can eliminate that as a variable in my rpm flutter as well as properly hooking up the egr valve.

Misc. Detail, for one reason or another although I have an 81 the Carter carb. that I have has no stepper motor or place for one to be put in. Also no computer to be found. So I believe that it is one from an older jeep put on my newer one.

Here are the pictures: http://www.flickr.com/photos/98174118@N08/

I need to know what A,B,C,D,E,F are supposed to go to.

Any and all help is greatly appreciated! :2thumbsup:
-Knox
 
See less See more
#8 ·
When I get more time I will try to help more specific. Have a little one and I have a hard time posting alot.

But start with this. There is no right way per se to hook up vacuum lines. Many different stock set up you will see. Google adventures under the hood and do everything not controlled by computer. Thats what I did. I have same carb no computer.

All that matters is you have right hose to right source of vacuum. Manifoild vs ported.
 
#9 ·
Ok I sort of gathered that, i often thought it would be helpful to know which port on my carb is ported vs non, and then to go with that find out what parts need ported vs non.

Are all the ports on the carb simply multiple ported and non ported, or are some specifically for one thing?

-Knox
 
#12 ·
KnoxButler said:
Ok I sort of gathered that, i often thought it would be helpful to know which port on my carb is ported vs non, and then to go with that find out what parts need ported vs non.

Are all the ports on the carb simply multiple ported and non ported, or are some specifically for one thing?

-Knox
I thought John posted the vacuum diagram for your year engine?
 
#13 ·
C- is ported I have it attached to CTO- that runs EGR and ported signal from evap canister
B- is manifold have hooked to air clear dampners
A- is capped on mine- I think it is manifold
D runs is a thermal switch I think and runs from the dampner on air cleaner that controls the exhaust coming in from the tube
E is a thermal switch the comes from CTO then to EGR
F is the dampner that open to let exhaust in during start up. Cant tell but mine has another dampner on air cleaner that block off intake to filter when engine is off-
both air clearner lines T together then tie into port B on mine
My dizzy advance is on manifold off the brake booster line. I think sometimes it is hooked into C.
COuld use A maybe?

Get a Vacuum pump/gauge it will help a lot
ported vacuum= 0 at idle and increases with throttle. ports located above throttle pplate
Manifold Vacuum= should be 18-20 at idle and falls with throttle- located below throttle plate

that all for now.

check out Advneture under the hood- esp for air cleaner operation
 
#21 ·
UPDATE: I bought a new fuel filter (just because im already messing around with it) and rotated it so that the return was 12 o'clock.



The way that my Jeep is now:
A- Goes to a canister of some sort that is connected immediately after the air pump.
B- Goes to the "Purge Signal" port on what I think is the vacuum canister.
C- Goes to the dizzy advance.
Everything else is not connected to anything.
EGR is capped

Does the EGR do anything except improve emissions?
 
#18 ·
-86CJ7 are you talking about this?
Yeah, don't even try to match up a BBD with a stepper BBD. there were a lot of changes in emissions laws between those years. Plus the added bonus of infant computer control.

Do you have an aluminum intake or steel intake? Makes a difference.

Here is a great link.
http://www.autozone.com/autozone/re...ageId=0900c152802523e0&CJPID=6146822&cmpid=cj

Here is a picture from that page:


Notice this was one of those years that the distibutor vacuum advance switched between maifold vacuum and ported vacuum depending upon engine temp.

Basically the thing to remember is, the EGR has to be connected ported vacuum and the CTO.
If so do the M, S, and E, mean somthing to that effect? M would stand for manifold but S and E?

Inowunderstand- do you mean that i should rotate the fuel filter or change the places of the hoses? Also what does the air cleaner dampener look like?

Thanks everyone this is really helping!
-Knox
 
#19 ·
On the filter rotate it around. The center nipple should go to carb. The return line nipple should be on top. This keeps gas from siphoning off down return line.

The air cleaner has these little trapdoors. One covers the exhaust tube coming in from the bottom and should open when cold to let in exhaust to warm up. It then closes. The other trapdoor was close to the filter and hung closed until you start motor and was sucked up to open air flow. The silver cup looking thing is what pulls the trapdoors open. They are just little metal door things
 
#24 ·
KnoxButler said:
Is it possible that having the EGR not hooked up could cause a flutter in the engine at high rpms? Kind of like its loosing a little bit of power?

-Knox
Not unless its leaking by. If your choke is not fully open when warmed up it will cause a rich condition. Its the first thing you should fix.

The EGR is 100% serviceable. As long as the diaphram isnt ripped, You can take it completely apart clean everything up and put it back together.
 
#25 ·
The choke is open all the way when I get the flutter.
When I start the engine from cold, the idle is smooth but rpms any higher start to make the engine "flutter" or shake. After the engine warms up it only happens in the higher rpms, just before I shift into a higher gear. Maybe that's a clue to the problem.
I don't think its the EGR, iv moved the diaphragm back and forth and it felt solid. Do you think it would be worth messing with it just in case?

-Knox
 
#26 ·
UPDATE: I rebuilt the carb as Jon In Tucson advised and it worked beautifully! Smooth idle and smooth at high rpms.

However I still have yet to do a full replacement of the vacuum lines because of a lack of a CTO or "ported vacuum switch" as a great deal of the important things were routed to it or from it. So I have ordered the part from Autozone and as soon as it gets here ill set to work on replacing all the lines.

-Knox
 
#28 ·
Great to hear Knox!
I have a 2 port CTO that was on my '83. I replaced it with the 4/5 port CTO when I did the TBI upgrade. You're welcome to it if you want it. Glad to see you are a member, best money I ever spent on my CJ. God bless.

Jon In Tucson
 
#29 ·
83vert- Im going to try and search for that thread so I can read it as well.
Jon-Thank you as well! I'v ordered the 4/5 port CTO but I appreciate your offer! Im happy to have become a member too! So much more usable now. Im sure ill be needing your help with something once i start working through the vacuum lines.

-Knox
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top