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Author Topic: New to the mysteries of the Quadrajet  (Read 20951 times)

Offline Dave Kay

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New to the mysteries of the Quadrajet
« on: September 29, 2007, 01:34:39 AM »
First off I'd like to say that as a newly registered member on this site I've found an incredible amount of info here and it's Heaven sent... a sincere thanks to all for that. My current project (read that headache) is a 1986 GMC C3500 w/5.7 ltr "M" engine and a TH400. Bought it on a lien-auction for practically nothing but as things have progressed I've found more and more wierd problemms that cause money to go out of my bank account. I live in southern California where I'm attempting to get this truck smog-legal. However, it's turned out to be more work than I thought because the previous owner was a total hack.

The Big Mystery for me is with the Quadrajet carb/choke; on mine there doesn't seem to be one. Strange as this may sound, I honestly must ask what is probably the dumbest/newbie question there could possibly be; where is the choke supposed to be mounted? I'm talking about an automatic choke. On the carb body or the intake? The carb-guys I've gone to for over 10 yrs looked at my Quardajet that I pulled for them to rebuild and when I asked where's the choke (there wasn't one on the carb body) they replied it must be on the intake manifold. Ok I said and mentioned that there also looks to be some linkage that's missing too... can you guys scare that up? However, when I got back home later that day I looked and sure enough, there wasn't anything resembling a choke on the intake at all. Wondered if maybe a choke could be some kind of vacuum actuated thing... anyway, upon further review I see no choke assembly on the intake and no open holes where it might be mounted, nor is there a choke housing assembly on the actual carb itself... a mystery. Is the carb wrong or the intake? Or...?

Hopefully some kindered soul will take pity on me for my ignorance... and (gulp) help?

DK
« Last Edit: September 29, 2007, 11:04:24 AM by Dave Kay »
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Offline Blazin

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Re: New to the mysteries of the Quadrajet
« Reply #1 on: September 29, 2007, 07:12:43 AM »
Well I will give you a welcome from the other side of the country, New Hampshaa!
 I am just a lowly body man so I can't answer your carb question. Carb. and vehicle electrical are my low points. I can wire a house but not a car, go figure!
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Offline VileZambonie

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Re: New to the mysteries of the Quadrajet
« Reply #2 on: September 29, 2007, 10:48:10 AM »
So I gathered you need a carburetor with a choke? Other than that I got lost reading your post... lol

You can buy a reman Q-jet electric choke for around $250 bucks from Autozone.
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Offline Dave Kay

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Re: New to the mysteries of the Quadrajet
« Reply #3 on: September 29, 2007, 11:19:10 AM »
Thanks Mr VileZambonie and pardon my rambling... (YEEESH!) Revised the post this morn to make it understandable... too much Tacate beer does strange things to the brain in the middle of the night...

And so I can't figure out what I have here: a wrong intake manifold or a wrong carb? That's the mystery. Not sure I want to go the Autozone route justt yet because from what i can see under the hood there doesn't look like an electrical connection for a choke either... another point here is I'm pulling the intake because it's been determined  there's a leak at the head and so wondering if it might be easier to just locate another intake w/choke mounting hole... anyone know how the intake numbers affect model year, etc.,?
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Offline VileZambonie

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Re: New to the mysteries of the Quadrajet
« Reply #4 on: September 29, 2007, 11:21:13 AM »
Wiring up an electric choke is a piece of cake.

Take a pic of the passenger side of the carb and the intake and post it here. We'll tell you what you have.
« Last Edit: September 29, 2007, 11:23:07 AM by VileZambonie »
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Offline Dave Kay

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Re: New to the mysteries of the Quadrajet
« Reply #5 on: September 29, 2007, 11:27:12 AM »
Quote from: VileZambonie on September 29, 2007, 11:21:13 AM
Wiring up an electric choke is a piece of cake.

Take a pic of the passenger side of the carb and the intake and post it here. We'll tell you what you have.

Roger that! Will post Monday when I get it back from the rebuilders, Thanks!
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Offline Captkaos

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Re: New to the mysteries of the Quadrajet
« Reply #6 on: September 29, 2007, 11:38:39 AM »
The choke for a Q-jet is mounted on the primary side.  Yours if it is Computer controlled should look like this:


Non computer controls look like this:
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Offline Dave Kay

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Re: New to the mysteries of the Quadrajet
« Reply #7 on: September 29, 2007, 11:01:43 PM »
Ok, attempting to post image of passenger side of carb... let's see if this works....
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Offline Dave Kay

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Re: New to the mysteries of the Quadrajet
« Reply #8 on: September 29, 2007, 11:15:48 PM »
Cool, it worked! So as you can see there's some stuff missing on the carb like a vacuum pull-off for the butterfly and linkage for the choke coil assembly which, if you look closely, there isn't anything there below the carb body on the manifold. The other pic of the intake after I pulled it; Only an EGR header, and hopefully you can see the second view with casting numbers... any help on identifying this intake would be appreciated.. it had obviously been replaced on this truck sometime in the past. Will post carb pics when I get it back from the builder on Monday. Ciao~!
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Offline Dave Kay

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Re: New to the mysteries of the Quadrajet
« Reply #9 on: September 29, 2007, 11:19:52 PM »
OOOPS! here's the other view of intake showing passenger side w/EGR header.... ;D
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Offline Dave Kay

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Re: New to the mysteries of the Quadrajet
« Reply #10 on: September 29, 2007, 11:24:09 PM »
And by the way, thanks a heap for your pics CaptKaos, I can now see what my carb is missing...
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Offline Dragon

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Re: New to the mysteries of the Quadrajet
« Reply #11 on: September 30, 2007, 12:49:54 AM »
Dave, looks like someone has replaced your Carb with a Non-Computer/Electric Older one that doesn't have a Choke.

Your '86 should have one that looks like the one I have on my '82 Olds Cutlass Wagon(If not a Manual Carb mounted Automatic Choke, which still looks like the pic, but minus the electrical connector to the side of the choke).
Not My Carb Pic, but looks like it.

The Round Object on the Left with the Connector going to it, is the Electric Choke, and the Vacuum Canister infront of it, is the Choke Pull-Off Valve.
1980's Electric Carb, with Automatic Manual Choke:


Your Current Carb, is the exact one I have on my '77 GMC, it is refered to as a '74-77 Quadra Jet Model 4MV with an Automatic "Divorced"(Means has a small choke mounted on the Intake Manifold and connected to the Carb via a rod).

Personally I prefer the Non-Electric Quadra Jets, for their ease of rebuild, but it looks like I have to add an Automatic Manual/Electric Choke, like you may want to.  :-\
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Offline Dave Kay

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Re: New to the mysteries of the Quadrajet
« Reply #12 on: September 30, 2007, 12:34:46 PM »
Thanks for the pics Mr. Dragon, the carb has been out of my hands since Thursday when I took it to the rebuilder but I believe it looks more like the second pic posted by Captkaos (the '80's non computer controlled) with mine missing the vacuum pull-off(s) along with the linkage for the butterfly... the jury is still out on this because I haven't heard back yet from my guy doing the rebuild... talked to him Sat and he's aware of the problem.

Haven't broached this idea to my rebuilder yet but am wondering if I can't just put a manual choke cable on it and go with that? Problem is, all the aftermarket choke/cable setups I've seen so far look like they install on an existing electric choke setup that is mounted on the carb-body, not on the intake... anybody ever try this on their rig?
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Offline Dave Kay

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Re: New to the mysteries of the Quadrajet
« Reply #13 on: September 30, 2007, 12:39:14 PM »
And by the way, does anyone know where I can get info on intake manifold casting numbers? Year? Application?

(see my previous post)

Thanks
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Offline VileZambonie

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Re: New to the mysteries of the Quadrajet
« Reply #14 on: September 30, 2007, 08:06:44 PM »
It's a mid 80's 305 cast iron 4 bbl manifold. It's a boat anchor. Your best bet is to find another electric choke carb.
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