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post #1 of (permalink) Old 01-27-2007, 10:39 AM Thread Starter
 
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Vac/Emissions gurus

I want to do a Nutter on my '85 CJ-7 4.2 I-6. I would like to keep an EGR on for emissions reasons. Unfortunately, EGR and canister Vac lines have all been down-sized. Pulse air sys has been altogether removed. I have a Weber 32-36 DGAV 33B1 and an Auto trans. My CTO has only TWO ports. Here is the plan, tell me what's wrong with it: EGR to outside CTO port and Tee'd to canister purge signal; Manifold vac Tee'd to inside CTO port, Tee'd to carb ported vac to distrib; Tee between PCV and carb to canister purge; carb bowl to can, can to tank. I tried to draw it but it sucked. What do you guys think? What do I need to add for it to work. Thanks, Johnny
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post #2 of (permalink) Old 01-27-2007, 06:53 PM
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Re: Vac/Emissions gurus

Well...if you took off the pulse air system, then messing with the EGR is not much use.

The EGR does not use full vac to operate....

In the stock setup, there is a temp controlled valve in the air cleaner that applies the metered vacuum to the EGR when the air temp is high enough. I think you are not going to like the results with what you plan....your going to end up with too much vacuum and the EGR will open up too much.

To be honest....I can't imagine why anyone wants to mess with carbs any more. Now that my CJ in fuel injected, I never mess with it...at least, not the engine...now I get to work on other stuff.
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post #3 of (permalink) Old 01-27-2007, 07:57 PM
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Re: Vac/Emissions gurus

The CTO is just an on-off switch with temperature, so it doesn't matter which ports you use - in or out.

The EGR and the cannister have to operate on PORTED vacuum - find it and hook it up. The CTO keeps it from operating until the engine's warmed up.

The distributor also has to be on PORTED too, but not controlled by the CTO. So tee in ahead of it for the dist.

You'll still have EGR that way, even without Pulse Air. You'll be still controlling NOx. The pulse air controls excessive HC and CO. They aren't really related.

By your explaination, the way I read it, you are connecting ported to manifold vacuum - DON'T!

If you are not in an emissions inspected area (you will be soon) then I'd go with the MC2100 carb - they work much better than the BBD ever thought about.



http://jeep.off-road.com/jeep/articl....jsp?id=261392
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post #4 of (permalink) Old 01-28-2007, 10:23 AM Thread Starter
 
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Re: Vac/Emissions gurus

"Well...if you took off the pulse air system, then messing with the EGR is not much use."

I did'nt. It came that way and I knew no different at the time.

"To be honest....I can't imagine why anyone wants to mess with carbs any more. Now that my CJ in fuel injected, I never mess with it."

EFI would cost more than I paid for the Jeep and there is no way I could afford it right now. But thanks for the positive feedback.

RRich thanks for the reply, you're right I did put manifold anf ported together, I won't hook it up like that. and if I can get at LEAST the EGR working it will be a step in the right direction. Thanks for the help, Johnny
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post #5 of (permalink) Old 01-29-2007, 05:05 AM
 
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Re: Vac/Emissions gurus

Here is what I did a one time except i didn't have a 2bbl BBD, just a 1 bbl YF so my manifold vacuum came right off the manifold. The YF has 2 ported vacuum connections.


This has a 4 port CTO but it's still Tee'd and acts kinda like what your planning. Just eliminate the EGR/TVS and put in a restrictor between the EGR and after the "T" to the purge signal. Otherwise I'm unsure how the vacuum canister will work when the EGR/TVS is operating.


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post #6 of (permalink) Old 01-29-2007, 08:07 AM Thread Starter
 
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Re: Vac/Emissions gurus

Chilton's claims there are a low and a high temp signal modulator which restricts the vacuum but neither are shown on the diagram. Does the EGR TVS restrict vac? And will the TVS work upside down? I have a wickedsmall air cleaner with the weber and I have little room to rig the TVS into it. Does the sise of the aircleaner effect carb performance or can I get an aftermarket Aircleaner and mount the TVS in it? -J
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post #7 of (permalink) Old 01-29-2007, 09:41 AM
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Re: Vac/Emissions gurus

Click on the Pic

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post #8 of (permalink) Old 01-29-2007, 10:03 AM
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Re: Vac/Emissions gurus

Great drawings LEVE! Good explanations too.

Essentially however it's set up initially - you don't want EGR till it's fully warmed up, and then only at higher speeds under load.

Cannister purge - most systems are the same way, only when warm, only at higher speeds (purging the cannister causes a slightly rivher condition till it's empty.) But then there's always the exception - some systems use the cannister purge to enrichen the system during warm-up - as a form of artificial enrichment - like a choke does.


Sometimes there are more than one ported vacuum - which to use for what?
As a general rule - of course with exceptions - put a vacuum gauge on the ported vacuum - rev it up:
- distributor vacuum will come on slowly the faster you go. - EGR vacuum will not be there until you reach a higher speed - but there needs to be something that keeps the EGR from working untill it's warmed up.


For purge you can use either one.

Many Jeeps use 1 or 2 control solenoids stock. They are operated by the computer - the computer determines if the temp and speeds are right. Then the solenoid(s) opens up, letting manifold vacuum through to the distributor, EGR, and purge. Everything happens at one - sometimes when driving it you can "feel" it all kick in. It hurts mileage but gets them past the smog laws.
When this type of system is removed, I've found folks really get things screwed up!

Back to basics - remember why, how, when each system should operate.
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post #9 of (permalink) Old 01-29-2007, 10:49 AM
 
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Re: Vac/Emissions gurus

Air cleaner housings have a big effect on carb performance.

A lot of good ones I've seen have a hump on the floor of the housing that prevents the air trying to make a right angle turn into the air horn. I think there is a book about " hot rodding your small block chevy " that realy covers the subject well but it applies to all carbed vehicals.

You can use a stock air cleaner housing on your Weber with the right adapter.

Either running one of these:
http://www.knfilters.com/Racing/plenum.htm
[image]http://www.knfilters.com/images/racing/85-1061.jpg[/image]

Or to the stock CJ/YJ air cleaner housing like this:
[image]http://forum.ih8mud.com/attachment.php?attachmentid=115310&stc=1&d =1169189961[/image]
[image]http://www.redlineweber.com/webers_are_back/All%20New%20K551%20Jeep%20conversions%[/image]
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