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post #1 of 11 Old 09-09-2011, 06:42 AM Thread Starter
boardmaker
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vacuum question with Weber

I have been reading a very good post started by cschaible. Thanks!

Toward the top of the post mcmud posted the following image.





I am running the same carb as cschaible. I have the breather in the above image. By the way, my vac hoses were every bit as messy. Maybe even worse.

Currently, I have the vacuum advance hooked to the carb, but plan to move that to the manifold as in the image. Brake assist to the manifold. PCV to the carb.

My bowl is not vented (plugged off). This brings me to my questions.

My EGR valve is not connected and I do not have a vacuum canister. What would be my best bet for getting getting all of the essentials hooked up? I would prefer not to buy a vacuum canister, but I will if it will help improve MPG or engine performance. Also, I assume the E and S ports are on the carb. I am not looking at my carb right now, but for some reason I was thinking I only have one port. Hopefully, I am wrong on this point. Any help is appreciated.

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post #2 of 11 Old 09-09-2011, 07:10 AM
oldtime_ironman
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It depends on the smog laws in your state. If they don't inspect for smog at all, then you can get rid of the charcoal cannister and the EGR completely. And then just put vacuum clockoff caps on the pipe nipples. The cannister doesn't make any performance difference either way, but if you do need one then you could pick one at most any junkyard - it doesn't matter much what it comes out of. I would definitely unplug the bowl vent tho - it'll make it easier for the float to do its job, and make it easier to keep the carb calibrated in the future - they depend on balancing air pressure.

.
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post #3 of 11 Old 09-09-2011, 09:41 AM Thread Starter
boardmaker
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No smog testing at all in my neck of the woods. I was under the impression that the EGR did function to increase gas mileage. Maybe not. If not, then the only vac hookups I would need are the advance, PCV and brakes?

One other thing, I noticed that some folks have a vac line to the front axle. I am pretty sure that I do not. Should I? I only tested 4WD to make sure it worked when I bought it. I just made sure the front tires spun and that was it. No real test.

Last edited by boardmaker; 09-09-2011 at 09:46 AM. Reason: added 'one other thing'
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post #4 of 11 Old 09-09-2011, 10:06 AM
oldtime_ironman
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Quote:
Originally Posted by boardmaker View Post
No smog testing at all in my neck of the woods. I was under the impression that the EGR did function to increase gas mileage. Maybe not. If not, then the only vac hookups I would need are the advance, PCV and brakes?

One other thing, I noticed that some folks have a vac line to the front axle. I am pretty sure that I do not. Should I? I only tested 4WD to make sure it worked when I bought it. I just made sure the front tires spun and that was it. No real test.
Yup, all you need are advance, PCV, and brakes. You definitely need the vac hookup to the front axle tho unless somebody modified your front end. The stock YJ uses the vacuum signal to switch the front axle in and out of 4WD.

.
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post #5 of 11 Old 09-09-2011, 11:18 AM
mcmud
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Higher fuel mileage will be the result of an adequate ignition system, proper spark timing (which you no longer have since the nutter, assuming you're running with the OEM distributor), and that working in conjunction with as near optimum a fuel mixture as you can obtain, from idle through the cruise speeds.

Once you read, comprehend the content and adhere to the guidelines found in the Redline tune guide you'll have the best chance to fit the mixture to the engine and your driving habits.

Setting a pre-computer distributor OR working the existing will bring back the spark advance that the 'nutter' has cost.

Aside from helping to prevent spark knock the use of the EGR valve benefits any and all that breath, with helping to reduce combustion emissions.

Typically the the "E" nipple will have a threaded plug set into it.

There is no harm with the bowl vent nipple plugged nor is there any benefit with that having been done, if the vents atop the cover are exposed to clean air inside the filter.

You may find the need of a vented filler cap since the charcoal canister is missing as well as fuel vapors escaping the tank vent tube until it is plugged.
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post #6 of 11 Old 09-09-2011, 12:28 PM Thread Starter
boardmaker
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If I am understanding correctly, my best bet will be to follow the above diagram to the degree possible. Without the vapor canister, I will basically ignore the green, brown, and gold lines?

If I can find the hookup on the front axle, would it be best to run that off of the manifold or off of a carb port? Regardless, I will have to use a T or Y connection to make this happen. Will that be a problem?

Thanks much.
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post #7 of 11 Old 09-09-2011, 12:35 PM
oldtime_ironman
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Quote:
Originally Posted by mcmud View Post
Higher fuel mileage will be the result of an adequate ignition system, proper spark timing (which you no longer have since the nutter, assuming you're running with the OEM distributor), and that working in conjunction with as near optimum a fuel mixture as you can obtain, from idle through the cruise speeds.

Once you read, comprehend the content and adhere to the guidelines found in the Redline tune guide you'll have the best chance to fit the mixture to the engine and your driving habits.

Setting a pre-computer distributor OR working the existing will bring back the spark advance that the 'nutter' has cost.

Aside from helping to prevent spark knock the use of the EGR valve benefits any and all that breath, with helping to reduce combustion emissions.

Typically the the "E" nipple will have a threaded plug set into it.

There is no harm with the bowl vent nipple plugged nor is there any benefit with that having been done, if the vents atop the cover are exposed to clean air inside the filter.

You may find the need of a vented filler cap since the charcoal canister is missing as well as fuel vapors escaping the tank vent tube until it is plugged.
Actually, regarding the EGR - since that subject was beaten to death years ago in the hot-rod forums. What happens is the EGR lowers combustion temperatures by diluting the air/fuel mix. When the EGR is removed, temperatures go up and pre-ignition occurs especially under heavy load. This can be compensated for by using a pre-smog distributor and adjusting the advance curve, along with re-adjusting the carb. You can still get advance curve kits for the HEI, effectively converting it into a pre-smog unit. It only costs a few bucks and takes all of 15 mins. With the proper setup, angines can live just fine for decades without EGR - it has already happened.

I guess I'll have to just flat disagree about the bowl vent though. I've never seen that work in the long run, and all my experience goes against it.

.
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post #8 of 11 Old 09-09-2011, 02:15 PM
mcmud
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This may help.
Notice that it is showing the use of the 4wd vacuum reservoir plumbed to the manifold vacuum source.
If you have it use it, if not plumb it direct to the actuator???

The one thing that you should not do is to plumb the axle actuator to a ported vacuum source without having the use of a reservoir.

Both of these vacuum layouts in this thread are complements of image edited versions of forum member GuacaTex originals, thanks to him for the use of each.
Attached Thumbnails
barebones.JPG  
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post #9 of 11 Old 09-12-2011, 06:44 AM Thread Starter
boardmaker
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mcmud,

Thanks for posting the bare bones diagram. To GuacaTex, I am sorry for not giving you credit for the original diagram.

This past weekend, I began to really trace out the vacuum lines and I fear that I may have a lot of work to do. Although the PO put the jeep in 4H and left rubber on pavement as 'proof' that 4wd works, he did it with the wheels cut hard right. I wonder if the excess friction with the tires cut may have made it seem that the front wheels were engaged. I put the front on jack stands and shifted to 4H. The hubs locked together, but even though I was in first gear wiht the engine off, the front wheels would spin freely. I assume this would not happen if the Xcase was engaged? Also, I fould 2 vacuum hoses that were plugged off an zip-tied out of the way. One went to the top of the Xcase and the other seemed to go to the top of the transmission. I also found that the rear seal was leaking on the Xcase.

I felt sorry for the PO as he seemed to be in a bind, but now I am thinking he may have gotten one over on me. In the end, I suppose all will be OK as I bought this Jeep to learn their ins and outs. I suppose I will have plenty of experience with that before I have it in good working order. I just keep telling myself that the engine, body and frame are in good shape. Of course, I have not checked compression yet! I reckon I am embarking on a great adventure.
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post #10 of 11 Old 03-10-2013, 08:59 AM
YJjeep258
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Hi I have a 92 Jeep Yj with the 2.5 liter but we swap it wth a 258 with the weber 32/36 with no emisions and I saw that post for the vacuum line hook up and on our jeep there was no vacuum resivor that I could see. So my question is could we hook the vacuum lines to the manifold instead of a resivor and still run properly? Also woul hurt to tee the s port on the carb to the distributor?
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post #11 of 11 Old 03-10-2013, 09:49 AM
roadyrob
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hook the vacuum hoses up like MCMuD's bare bones diagram only with out the res, it isn't needed. you are better off running manifold vac for the distributor.

Do everything with a positive attitude, it won't always work but you'll piss enough people off to make it worthwhile.

the voices aren't real but they sure have good ideas.
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