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Need help with 84 CJ7 vacuum hoses!!!!

38K views 106 replies 11 participants last post by  Crazy_Jeeper_7 
#1 ·
I am trying to get my 258 4.2L amc engine to run, and the first to tackle are the vacuum hoses and where their correct locations are. When I got the jeep there were zero hoses hooked up, so thought that maybe hooking the hoses up correctly could be vital in this rebuild. Anyone have any diagrams/photos/videos that point me towards the right path. Suggestions and advice are appreciated.
 

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#5 ·
HAve a good look at what you hav ether ebefore you assume it will all just hook up and run properly.

What are the laws like in your State, do you need to get it back to original?

I would then look at the following:

What carb have you got? It does not look like a Certer BBD with a stepper motor so some of thet emissions equipment will never work unless you get one.
What air filter have you got? Some of that hooks up to the TAC. No TAC = No hoses to attach
What exhaust headers are you running? I cannot see clearly if you have the original cast headers. If you have tubular then that EGR valve is not going to work.
Do you have a brake booster? Sorry, photo is blurred and I cannot see it.

Some of the kit in the diagram posted above would be fine and dandy to have, like the Forward Delay etc but how many of those bits have you got?

If you want to see if it can run properly you only need 2 hoses, one between the distributor and carb and one from the manifold to the brake booster (if you have one). I would then stopper every other port in the carb and manifold. The port on the carb for the distributor can be ported or manifold vacuum, you need to work out what they are. Basically manifold sucks at idle, ported only higher up. Manifold may make it run better. Once it i srunning straight you could look at the PCV hose and hooking up the vacuum canister to purge various emissions etc etc

If you have the computer controlled type Motorcraft DUraspark ignition just see if it is nuttered. Basically the sensor wires from the distributor should go to the ICM and not up into the dash area to the computer.
 
#6 ·
Yeah me and two guys I know that work on jeeps were thinking it wasnt the original carb, but we cannot seem to find a brand name or anything. The PO put an edlebrock (or however u spell it) air filter on it. It does not have a brake booster either. And by the way, I live in georgia so we dont have smog tests done or anything. Im thinking the headers are original because they are more square than tubular.
 
#7 ·
Looks like a MC2100 carb. If you going to keep the carb and not worry about all the emissions stuff do the nutter bypass. These diagrams should help witht the vacuum lines. They are both the same except one if for 2 port cto the other ia 5 port cto. Yes, if the vacuum lines are not hook up or not hook up at all the engine may not run or may not idle or run correctly.
 

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#9 ·
Do search on this site ot do a google search you will find tons of stuff. But basiclly you are bypassing the computer between the Ignition Control Modual(ICM) to the distributor. You run 2 wires from the ICM to the distributor. Then you set the timing to 8* BTC. Its really easy, and puts the Jeep back to the pre computer era.
 
#14 ·
ok, i have a guy coming over to help me with the vacuum hoses first, we are going to see if we can get it back to like when it was stock. But if that goes down hill, then we will be doing the bypass.
 
#15 ·
If you have the original exhaust headers they connect to the bottom of the inlet manifold, there is a gasket etc. If they are not connected the EGR valve has nothing to do as it has no Exhaust Gases to Recirculate.

Good luck with sorting out all that spaghetti, I suggest getting hold of the Factory Service Manual which has a whole section on the emissions control.
 
#19 ·
Yes, I have Bagusjeep and Puthijeep set up that way.

Just a simple 50c length of hose from the carb to the distributor.

It will run absolutely fine and you can eliminate all other sources of issues with the engine before you add more complexity. Later on you can think about the tank vent, crankcase breather and all the other stuff that I have never connected.

With the other connections on to the carb that are currently open you can plug them by fitting a short length of the same hose but with something rammed in the end of it to stop it leaking. Some people use golf tees, ball bearings. screws, small bolts etc or the hose is just folded over and tied. They are temporary and easy to take back off.
 
#21 ·
Alright, I cant seem to get my buddy to come over to help.... so I guess its just me on this project. I have tried looking at diagrams for vacuum hose routing, but i get sooooo lost. there are so many things that are on the diagrams that I am missing so its hard to get it back right. I know if I do the nutter bypass, it will eliminate a lot of hoses, but how about I dont even have a CTO valve, so how would I go about doing the nutter bypass?
 
#23 ·
Follow the diagrams I posted in post #7. All you need there is EGR, Canister, PCV on top of the valve cover and distributor, which you have. You have posted pictures of all that in your orginal post. Now for the CTO there are usually two types a 2 port or 5 port. My 84 has a 2 port which is in the picture below. It should be on the intake manifold below the carb. If you are looking at the carb from the drives side it will be to the left of the carb.
 

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#29 ·
I don't have one, just a single hose from carb to distributor.

Seriously, start off simple and get the engine running first, then worry about the mysetries of AMC vaccumm lines.
 
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