Author Topic: 1983 quadrajet vacuum connections  (Read 8357 times)

Offline Megacarfan

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1983 quadrajet vacuum connections
« on: March 18, 2009, 10:36:46 AM »
Just wondering if anyone could help me with this.
I have a new quadrajet for my truck and need vacuum diagrams.
I want to eliminate any unnecessary stuff but still keep it pretty stock.
Thanks in advance.

Offline Lt.Del

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Re: 1983 quadrajet vacuum connections
« Reply #1 on: March 18, 2009, 12:33:38 PM »
you contradict yourself.  You want to eliminate all unnecessary stuff but keep it stock?? ???

It is either / or, can't be both.

Mine is a 79, it may be mainly the same.   I took digital pics when i removed the old motor in prep for the new motor.  I kept min all stock including EGR, Charcoal canister, TVS, etc..

check it out www.delbridge.net/vacuum.html

Also look on your radiator support  for the silver looking decal / diagram that displays vacuum lines / routes.


Offline Megacarfan

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Re: 1983 quadrajet vacuum connections
« Reply #2 on: March 19, 2009, 08:38:15 AM »
touche' fellow truck dude...........touche'  :)
I really appreciate your feedback and the truth is, I do want to keep it stock.
The one main thing I want to eliminate is the thing that runs to my exhaust manifold, (not sure what it is called) can you tell me?
Anyway, I will check out your link.  Thanks a bunch.

Offline Stewart G Griffin

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Re: 1983 quadrajet vacuum connections
« Reply #3 on: March 19, 2009, 08:53:24 AM »


1) i also have an 83 and if you can wait maybe 1 or 2 weeks or possibly longer, i am going to get whole-hog into a 100% tuneup/checkout and possibly rebuild on my engine.  i know very little to jack at this point about vacuum lines, however i am very anal and neurotic and thus i eventually get things right;  Also, see 2a below.
So, there are two risks associated with following me:
it will probably be slow.
you might mess things up, but eventually things will probably turn out ok.



2)  Initially, it appears that(and also depending on your emmissions laws) that all you need is the vacuum going to the brake booster and vacuum advance canister on the distributor. Also vacuum to the heater and a/c controls(i think?)
a) if we get in trouble, there are nice and helpful people on here and other sites that can "bail us out."

b) i think i also have the diagrams in my service manual which i may either scan and post here or if that goes against copyright rules (i'm not sure if this even affects gm at this point), i could email to you.

3) the thing that runs to the exh manifold is, i'M pretty sure, the "EARLY FUEL EVAPORATION SYSTEM" which basically helps heat the fuel when you've just started off in the morning or whenever it's cold.  As you can see on my truck, the prev. owner's shop took it off when they swapped engines because it was a north carolina truck and apparently it never got cold enough etc.  But like i said, i don't have time to get into it too deep right now.
« Last Edit: March 19, 2009, 08:57:34 AM by Stewart G Griffin »

Offline ccz145a

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Re: 1983 quadrajet vacuum connections
« Reply #4 on: March 19, 2009, 08:55:22 AM »
The one main thing I want to eliminate is the thing that runs to my exhaust manifold, (not sure what it is called) can you tell me?

The thing that runs to the exaust manifold is part of the A.I.R. system. It really does no harm other than it's ugly and takes up space... it injects mildly compressed air into the manifold to assist in the full combustion of left over gasses, thus reducing the carbon monoxide output. It does not take a lot of power to turn the compressor.

It will run fine without it, though.

1975 C10 Silverado LWB, 454CID, TH400, 10bolt 3.42
11MPG Downhill w/tailwind (but there ain't no hills here)

Offline Stewart G Griffin

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Re: 1983 quadrajet vacuum connections
« Reply #5 on: March 19, 2009, 09:09:11 AM »
  Could you post a picture? 

Let's clarify here;  Are u talking about the "thing" that runs to the passenger side exh manifold?  Or silver metallic tubes that run to both exhaust manifolds near the plugs?
« Last Edit: March 19, 2009, 09:14:08 AM by Stewart G Griffin »

Offline ccz145a

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Re: 1983 quadrajet vacuum connections
« Reply #6 on: March 19, 2009, 11:18:36 AM »
Good question Stewart... I was assuming the second of your questions, the ones that go to both manifolds.
1975 C10 Silverado LWB, 454CID, TH400, 10bolt 3.42
11MPG Downhill w/tailwind (but there ain't no hills here)

Offline Lt.Del

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Re: 1983 quadrajet vacuum connections
« Reply #7 on: March 19, 2009, 11:26:09 AM »
are you talking about this thing on the left side of the pic?



If so, it closes a valve so exhaust won't flow through the exhaust but instead reroutes the heat through the intake to warm up the engine fast.  After a couple of minutes, the TVS line hooked up to the ugly thing opens up the exhaust valve letting exhaust go through the pipes.

Offline oldwhity

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Re: 1983 quadrajet vacuum connections
« Reply #8 on: March 19, 2009, 08:11:15 PM »
The lines associated with the smog pump?
Rob G.
81 Chevy K20 4x4 LWB stepside
I enjoy long quiet walks..........in a junkyard!

Offline Megacarfan

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Re: 1983 quadrajet vacuum connections
« Reply #9 on: March 20, 2009, 10:25:16 AM »
By the way, I hail from West "By God" Virginia, (no offense to unaffiliated religions) ;D

The one I am talking about opens and closes the butterfly type valve down by the donut gasket inside the exhaust manifold.  Upon inspection, someone has removed the butterfly valve.  Should I just get rid of the whole vacuum assembly and plug the connection at the carb?  Will I need to replace the manifold to make it perform correctly?

Also, in this one picture.....What is the thing with the big green "b"?
Mine has that too, it mounts in the thermostat housing water jacket.

Mine does not have a smog pump.

Also, regarding the tubes that run to both sides, I have not identified those yet.

I WILL post pics soon.

I want this truck to be as fuel efficient as possible as I like to drive it.  Right now, I am lucky to get 11 mpg.  VERY LUCKY!

Thanks to all who replied, please continue with the feedback, it helps a lot to know that there are others out there with me.

Offline Stewart G Griffin

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Re: 1983 quadrajet vacuum connections
« Reply #10 on: March 20, 2009, 01:03:14 PM »
1) west virginia is a decent state;  Also one of the few not really affected by the economy?

2) In that case, then it is the "early fuel evaporation system."  And yes, if someone did remove the butterfly valve then you should probably remove the complete vacuum assembly altogether.  i'm not sure exactly how to go about plugging and/or re-routing the vacuum lines because i'm too busy right now.  i don't think you'll need to replace the manifold.

3) i have no idea what the big green "b" is in my picture;  i think it is a TVS (themal vacuum switch).  And what this does is it only allows air/vacuum to flow only when the coolant temp reaches a certain level.  Or it shuts off air/vacuum at a pre-determined level.  Pretty nifty eh?   But give me time and we will both get into it big time.

4) Yes, i didn't think so;  i don't think most 83's came with A.I.R. pumps except for the california and/or above 1/2 ton models.
a) If you don't have a smog pump, then you don't have the silvery metalic tubes running to each exhaust manifolds.


5)RE: MPG  Something may be wrong as i am able to average 16mpg with a high of 17.1ish achieved last summer.  How fast do you drive and do you do alot of mountains?

Offline oldwhity

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Re: 1983 quadrajet vacuum connections
« Reply #11 on: March 20, 2009, 07:38:22 PM »
My 81 had those lines in each manifold and they were connected to the smog pump(unless I misidentified it). I removed all that when I installed headers.

I also removed the vac assy that controls the butterfly in the exhaust. Just remember to cap the open nipple when you remove the vac line to the assy.

I just went out to look at my 85 and noticed that the butterfly was not hooked up. I'll be removing that one too.

BTW the 85 is getting 13.1 mpg's. It's a 2wd with a 305(haven't checked the casting #'s yet). It has a heavy "Reading" cap on it with 2 air compressors, generator, hose reel, and misc. tools. The first tank got about 12. Hopefully i can squeeze more.
Rob G.
81 Chevy K20 4x4 LWB stepside
I enjoy long quiet walks..........in a junkyard!

Offline Lt.Del

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Re: 1983 quadrajet vacuum connections
« Reply #12 on: March 20, 2009, 09:02:54 PM »
Stewart is correct about the green B.  It is the TVS.  It controls quite a bit of stuff and activates when the thermostadt opens, signaling that the engine is warm.

I changed mine when i put in my 383.  They run about $20. The stems on these puppies break off easily and that is the source of many, many vacuum leaks and the cause for low mpg's.

Offline Dave Kay

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Re: 1983 quadrajet vacuum connections
« Reply #13 on: March 25, 2009, 11:57:10 PM »
For emmisions diagrams go here http://www.autozone.com/autozone/

I didn't do the digging for you so search your vehicle model, etc., and this may help. Sure did for me!


 


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