Author Topic: Vacuum Diagram 1977 GMC K10  (Read 6008 times)

Offline tlsmikey

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Vacuum Diagram 1977 GMC K10
« on: January 12, 2006, 02:15:00 PM »
I'm desperately trying to find a vacuum diagram for my 1977 GMC K10, but my haynes manual doesn't have anything.  Does anyone know where I can find one?  I'm trying to figure out which lines go the carb and to the little charcoal cannister...etc.


Offline Lt.Del

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> Vacuum Diagram 1977 GMC K10
« Reply #1 on: January 12, 2006, 08:36:00 PM »
There should be a rectangular sticker visibile once you pop the hood, near the hood latch, on radiator support.  It is silver in color.  It will give you the vacuum schematics.  

I have a 79, and it should be similar.  Can you take a digital pic of hose (s) in question and post.  I am sure I can tell you where it goes.

SgtDel


Offline tlsmikey

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Re: > Vacuum Diagram 1977 GMC K10
« Reply #2 on: January 13, 2006, 12:18:00 PM »
Unfortunately, my hood was replaced with a fiberglass panel and the whole engine bay is completely void of factory stickers now.  

I rebuilt the motor and neglected to take pics of the "pre-smog" setup.  

I need to know where the following hoses go:

1) vacuum port from advance can on distributor
2) all of the carb ports
3) charcoal cannister on firewall
4) two ports on the air cleaner

thanks,
Mike


Offline Lt.Del

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Re: > Vacuum Diagram 1977 GMC K10
« Reply #3 on: January 14, 2006, 11:04:00 PM »
I will look at my truck tomorrow and get back with you...I do know...


the air cleaner has two hoses.  ....

One little one attached to the base of the cleaner connects to a small T vacuum connector leading from carb to another part of the carb. Next to connector as auto trans modulator, if  i recall correctly.






The fat hose goes to the valve cover.  It should only be about five inches long.  It pushes into a hole in your valve cover.    

There should be no charcoal cannister on the firewall, but behind the left headlight.  

SgtDel

Edited by: SgtDel at: 1/14/06 11:13 pm

Offline Lt.Del

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Re: > Vacuum Diagram 1977 GMC K10
« Reply #4 on: January 14, 2006, 11:25:00 PM »
Vacuum Advance





Charcoal cannister hookup





charcoal cannister....










SgtDel

Edited by: SgtDel at: 1/14/06 11:34 pm

Offline Lt.Del

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> Re: > Vacuum Diagram 1977 GMC K10
« Reply #5 on: January 14, 2006, 10:40:00 PM »
Another carb hose goes to pvc valve in valve cover...





SgtDel


Offline Lt.Del

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> Re: > Vacuum Diagram 1977 GMC K10
« Reply #6 on: January 14, 2006, 10:45:00 PM »
How's about this hodge-podge of vacuum lines?



Offline adamrx7

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Re: > Re: > Vacuum Diagram 1977 GMC K10
« Reply #7 on: February 11, 2006, 12:25:00 PM »
Hi guys Im having a problem with my vacuume lines also. It's the last thing I need to do to start this turck. Heres is a pic of what I have, can you tell me where each line goes?

img.photobucket.com/album...7/carb.jpg

Adam
93 RX-7 and
89 Colt(4g63)

Edited by: adamrx7 at: 2/11/06 12:29 pm

Offline Lt.Del

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> Re: > Re: > Vacuum Diagram 1977 GMC K10
« Reply #8 on: February 11, 2006, 03:40:00 PM »
Adam

You may want to post a new thread next time, but here are some pics that should help you if your vehicle is stock...egr, charcoal canister, etc....I have a 79, but it should be similar to yours...  They are calling for 6 inches of snow here in Va, so if you need more pics, I'll have to sweep the snow off the hood.













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Edited by: SgtDel at: 2/11/06 3:48 pm

Offline adamrx7

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Re: > Re: > Re: > Vacuum Diagram 1977 GMC K10
« Reply #9 on: February 11, 2006, 09:02:00 PM »
Thanks Del I think I got it. Hopefully tomarrow I'll start this puppy.

Adam
93 RX-7 and
89 Colt(4g63)


Offline 83silverado

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Re: > Re: > Re: > Vacuum Diagram 1977 GMC K10
« Reply #10 on: February 12, 2006, 10:39:00 PM »
These pics are a big help to me as well.  I have an 83 with a Quadrajet.  Almost no vacuum lines are currently hooked up.  Only the largest line is currently hooked up to the cannister.  Also, my carb has an electric choke- at least there is a wire and a connector hooked up there.  I have real problems with fast idle kickdown, so mabe it's not working.

I don't have any of the little check valves or t connectors that I see in most of these pictures, and I also don't have that thermal vacuum switch.  Can those check valves be purchased somewhere, or can I do without them?

Next, in the very first picture posted, there is a line coming out of the top back of the carb- looks like rubber to start, and then steel.  Where does that go?

Lastly, in the same picture, there is a dashpot on the carb right next to the vacuum advance on the distributor.  Mine has a port sticking straight out the back with no hose on it.  Where dose that go?

I know this is long, but I appreciate the help.

Edited by: 83silverado at: 2/12/06 10:45 pm

Offline Lt.Del

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Re: > Vacuum Diagram 1977 GMC K10
« Reply #11 on: February 13, 2006, 10:53:00 AM »
That hose you refer to is one of two things.  There is a rubber hose, changing to metal from the intake...that goes to the transmission modulator.  But i think the one you refer to is the rubber hose changing to metal that goes up under my choke coil.  That simply loops inside the intake for an inch or two then coomes back out.....it is to warm up the air. That new metal lines simply comes from the intake to the hot air choke....you shouldn't have that if you have electric.

About the TVS thermal vacuum switch....yes, you can purchase those at any good auto parts store.  I bought a new one for my new 383 when i installed it.  The one coming from the thermostadt housing should have a few little plastic stems on it to hook up the rubber hose housing...it just pushes on.  There's another one that screws into the intake manifold next to the thermastadt housing. I used my old one there that came off my old motor. I am sure you can replace that too.

As for the check vavles....i guess you can get those from the auto parts store, or rip them off an old vehicle from a salvage yard...I used my original ones.   I think all they do is ensure vacuum goes only one way.  I could be wrong.

  Q:   "Lastly, in the same picture, there is a dashpot on the carb right next to the vacuum advance on the distributor. Mine has a port sticking straight out the back with no hose on it. Where dose that go?"    

  A:   I think you are talking about the line that just goes to the bottom of the carb.  There is a T in it that branches to the air cleaner housing.

SgtDel
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Edited by: SgtDel at: 2/13/06 7:34 pm

Offline 83silverado

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Re: > Vacuum Diagram 1977 GMC K10
« Reply #12 on: February 13, 2006, 09:48:00 PM »
Any sense of whether my truck will pass emissions without having all of these lines connected?  I bought the truck in Arkansas, and they must not have to pass emissions there.  Right now, there are almost none of these hoses attached, and yet it runs well without them.


Offline Lt.Del

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Re: > Vacuum Diagram 1977 GMC K10
« Reply #13 on: February 14, 2006, 08:44:00 AM »
You can plug up a lot of these vacuum ports and it will run very well, probably better gas mileage too.  But w/ the egr and charcoal canister and tvs activations and choke, etc, you need these things.

It really depends on what state or even metro area you are in whether or not it will pass.  In Va, there are several areas within this state (Norfolk?, Va Beach? area and norhtern Va near D.C.) that requires emissions testing.  Right now, Richmond does not require emissions testing...just better have your catalytic converter on for the state inpections.   We may change here, so i kept all of my stuff on it when i put the new 383 in it. It is better to be safe than sorry.

I know many people who took all the "smog" stuff off.  It is a federal violation but whether you get caught is another story.  

SgtDel


Offline 83silverado

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Re: > Vacuum Diagram 1977 GMC K10
« Reply #14 on: February 14, 2006, 10:28:00 PM »
Well, that's just it-  I don't seem to have a EGR, TVS, or most of my vacuum lines.  I also found out tonight that there are no catalytic converters, either.  Just straight pipes and mufflers, so I am assuming at this point that there is no hope of passing emissions- In fact, probably shoudn't even take in in without the cats on it.  Sooo...not sure how to proceed at this point.  I need to be able to legally drive this truck...


 


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