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Posted By: 84G20HiTop Vacuum lines and EGR - May 17th 2019 5:28 pm
Hello all, newer here. Bringing an old Class B, my first Chevy, back to life. I pulled my emissions crap off, capped the manifolds, now I’m re doing the vacuum lines. I’m wondering if someone could help with a few questions:

Do I simply delete all vacuum lines that went to the emissions crap, reroute them as if they were never there?

Most of these lines are turning to dust when pulling them off, anyone know the sizes? I have the vacuum diagram but it doesn’t show them. Looks to be 2 or 3 different sizes. The only one in good shape is the brake booster.

Are the Haynes or Chiltons manuals worthwhile for this van?

Thank you. I’ll try to post a couple pics of what im looking at now.
Posted By: 84G20HiTop Re: Vacuum lines and EGR - May 17th 2019 5:35 pm
Few images.

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Posted By: 84G20HiTop Re: Vacuum lines and EGR - May 18th 2019 9:46 pm
Well reading that chart, or learning to read it rather, was pretty interesting. Going from engines that create air with a mounted air compressor (DD’s, S60’s or ISX’s) to one that creates used vacuum was fun. Chart was not hard to read. I just picked an accessory and worked to the end of the run then went to another one until they all let up at the carb. Even hoses that should’ve been there were not there before I went in. Fun. I also removed the smog pump and manifold injection valves and put in 1/2” (x18 or 20, can’t remember which) plugs from Lowe’s. I left the EGR for now because I read it may need a tune or some other cats. What I read about someone removing all but 1 or 2 vacuum lines was from a tuned and modified engine.
Thanks for the help.

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Posted By: NEmery Re: Vacuum lines and EGR - May 20th 2019 6:45 pm
i am curious to know this as well. I would love to delete as much vacuum stuff as I can. my van is a 79 with the 350 SBC and all the smog stuff pulled off the manifolds, too.
Posted By: NEmery Re: Vacuum lines and EGR - May 20th 2019 6:46 pm
what chart were you using?
Posted By: Reed Re: Vacuum lines and EGR - May 20th 2019 7:10 pm
FYI- the air injection is more important to te catalytic converter on a cabureted engine than is the EGR valve, but both are beneficial to the engine and should be left intact and functioning.
Posted By: Hasan Ben Sobar Re: Vacuum lines and EGR - May 21st 2019 2:17 am
Air injection is an emissions thing only. In 1967 Pontiac had A.I.R. on California cars , which had closed chambers heads. In 68, the heads went to a open chamber design and the "smog pump" was no longer needed and was never seen again on a Pontiac.

Pinch off the vacuum line to the EGR valve while the engine is running. If the idle changes-the valve is bad. Then pull the valve and install a block off plate. If the vehicle runs "different"-the valve is also bad but leaking externally.
Posted By: Reed Re: Vacuum lines and EGR - May 21st 2019 3:40 am
But air injection allows a cleaner burn of the exhaust in the catalytic converter and helps a converter survive longer behind a carb. Air injection helps prevent the overheating of the catalyst and the breakdown of the matrix which leads to clogged cats and exhausts.

EGR helps with controlling engine park knock and is a useful tuning tool.
Posted By: 84G20HiTop Re: Vacuum lines and EGR - May 21st 2019 4:01 am
Originally Posted by NEmery
i am curious to know this as well. I would love to delete as much vacuum stuff as I can. my van is a 79 with the 350 SBC and all the smog stuff pulled off the manifolds, too.


I believe there were some lines under the hood that were missing and not on the chart. I got the Tip In Sw with the two wires and the Trans vac switch with the green and blue(?) wire and a small vac line coming out of the back.

What I don’t have, and is not on the diagram XDK (pic) is the vacuum reservoir to the T and beyond.

Also, what else is not on the diagram is the main engine vacuum having two hoses off of it. One is on the diagram, the other goes to a T, then to the front under the hood somewhere and to the second pic I have. In this case, it broke off on a minor brush. Any idea what that is?

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Posted By: 84G20HiTop Re: Vacuum lines and EGR - May 21st 2019 4:09 am
Originally Posted by Reed
But air injection allows a cleaner burn of the exhaust in the catalytic converter and helps a converter survive longer behind a carb. Air injection helps prevent the overheating of the catalyst and the breakdown of the matrix which leads to clogged cats and exhausts.

EGR helps with controlling engine park knock and is a useful tuning tool.


I’ve never bought that stuff, no offense. Emissions are for government to convert our rights of private property into regulated, taxable privileges. And cats won’t be a problem either. With proper tuning, any engine will run better than any with restricting emissions.

Back to the topic, do you know what they are?
Posted By: 84G20HiTop Re: Vacuum lines and EGR - May 21st 2019 4:19 am
Originally Posted by Hasan Ben Sobar
Then pull the valve and install a block off plate. If the vehicle runs "different"-the valve is also bad but leaking externally.


I don’t think I have the resources available to do a complete emissions removal. Definitely don’t have the know how on this gasoline burning antique. I looked everywhere in town for a block off plate. No luck.
Posted By: 84G20HiTop Re: Vacuum lines and EGR - May 21st 2019 4:20 am
Anyone know what this is that broke when I brushed up on it?

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Posted By: Hasan Ben Sobar Re: Vacuum lines and EGR - May 21st 2019 4:21 am
Originally Posted by Reed
But air injection allows a cleaner burn of the exhaust in the catalytic converter and helps a converter survive longer behind a carb. Air injection helps prevent the overheating of the catalyst and the breakdown of the matrix which leads to clogged cats and exhausts.

EGR helps with controlling engine park knock and is a useful tuning tool.

No car uses air injection today.
Posted By: Reed Re: Vacuum lines and EGR - May 21st 2019 5:24 am
Thats right. They don't use EGR, either, because combustion chamber, timing control, fuel control, catalytic converter, and valve control technology has advanced so much since the 1980s. That doesn't mean the old engines and vans don't need an air pump.
Posted By: CatFish Re: Vacuum lines and EGR - May 21st 2019 1:59 pm
Remove the EGR completely and discard it. It was a stop-gap, half assed gesture by greedy car manufacturers to appease ignorant and confused law makers. The fact that it does very little to lower actual emissions compared to the damage it does to the engine is reason enough to chuck it. Net emissions actually increase over time from all the engines that are carboned up and running improperly with EGR.
No one ever, ever thought that recirculating burned exhaust gases back into the engine was a good idea. No Body! It simply reburned a portion of the gases on new engines, enough to say it lower emissions a faction to satisfy the inadequate standard of the day. It was a miserable failure in the long run.
Posted By: jcd74 Re: Vacuum lines and EGR - May 21st 2019 11:19 pm
Have cruise control?
Posted By: jcd74 Re: Vacuum lines and EGR - May 21st 2019 11:22 pm
Sorry 6 posts back up to pic.
Posted By: Frosty Re: Vacuum lines and EGR - September 20th 2020 12:11 pm
Thank you CatFish, you answered my question. Most of my emissions lines and such are plugged up or discarded when I bought my van. I saw the EGR and wondered what to do about it. Now I know.

I'll fabricate a block off plate and that'll be the end of that!
Posted By: kgravlin Re: Vacuum lines and EGR - February 06th 2023 12:14 am
Hello,
I recently bought a 1984 G20 also I am wondering how your vacuum system efforts came out. It's a true spaghetti party. I bought 30ft of different colors of vacuum line intending to just just follow the pieces and replace the entire mess but due to age-rot more than half a dozen lines are just laying there connected at one end at best sometimes neither end and only sometimes clear where it was connected. Although I have the same XDK diagram it's hard to see that it actually follows it as I have found multiple hose paths that do not. Can you tell me what you ended up doing and if you could correlate between the diagram/vehicle? One of the issues is that I have found no pictures that show each component of the vacuum/pollution system so I can correlate an element on the diagram with a physical device on the engine. Some times I can via the hoses/paths but not always. I would be happy to reduce it to minimum (i.e. vacuum advance line, etc) needed but don't want to accidently undo something that affects mpg or operation. Any resources you found and/or help is appreciated.
Keith
Posted By: jcd74 Re: Vacuum lines and EGR - February 06th 2023 1:03 am
Do you have 4 speed tranny? the only things you should worry about are PVC and vacuum advance. If you have the 700r4 you need to worry about the converter Best thing you can do is aftermarket carb and dizzy.
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