Carb Gurus - Need help!

[IndianaK2500]

Ok, first post, a question. And yes, I did search.

Anyway, I just bought a 1983 GMC 3/4 ton 4x4 (350, 700R4)last week, and the carb is giving me fits! First thing, it's missing ALOT of parts, there are several "rods" that are missing, etc, etc.

So, I'm thinking that I have one of two options. First, I can go to a junkyard and find another q-jet to put on it, and hope it's "ok". The second, is to purchase a Holley Spreadbore replacement, and go with that. (This isn't for offroad, I have another vehicle for offroad, this is my "towrig")

So, basically I'm looking for something that's gonna give me good performance while towing, and won't give me fits.

Any suggestions?

 

[IndianaK2500]

Oh, yea.

This thing isn't "computer controlled" is it? I'm looking at different carbs and some mention computer controlled Q-jets.

 

[dyeager535]

Not computer controlled in '83.

There is a third option, which is get a QJ that needs rebuilt (a core if you will) and make one good carb out of two. the rebuild kit is less than $20 9or should be) and if one of the two is good, you won't have problems with the primary throttle shaft needing to be bushed.

Core QJ should run you about $5. I've got some parts, as others on here do as well I'm sure, so check out www.dorianyeager.com/index2.html
Why insist on counting when the ring gear has the tooth counts stamped in?

 

[Grim-Reaper]

Don't get a holly...they suck.
Me I would be getting the junkyard carb or finding a used carb in the for sale board. If your willing to throw some coin at the deal get the new Quad from Edlebrock. It's a real Quad and it is new and it should bolt on and not need much else. Get the one with electric choke.

Women dig dents and flat paint!
coloradok5.com/gallery/Grim
75 Jimmy, Dollar
Grim-Reaper

 

[IndianaK2500]

Dorian, thanks for the info.

Actually, what I did was not too far off. I put a manual choke on it, that seemed easiest and cheapest. I also fixed the "Low idle" too, so that's good. I think I'm about 95%.

So, now I have another Q. On the passenger side of the carb, there seems to be a vaccuum for the secondaries. Now, I believe that there should be a rod that goes from that vacuum, up to a "lever" on the secondaries to open them up? Is that what it is? I looked on your diagram's, and it would seem to be #58 or #322. But, more like 322, going from 320, up to where #58 attaches?

Seems kind of F----d up, if you know what I mean. I also started tearing off the emissions control stuff, and it still seemed to run ok, so that's cool!

Thanks again!

 

[dyeager535]

Do you have both of the "vacuum cannisters", like in that pic? 322 is for the choke operation, which CAN affect the secondaries, and 58 is for the secondary air valve.

The secondaries are held SHUT with vacuum actually, when vacuum drops, (and choke is off) the vacuum relaxes tension on those rods, allowing the secondary air valve ("upper rear butterflies") to open. Incoming air holds it open.

Missing that upper rod will only allow the secondaries to open without regard to engine vacuum, (kind of) but that can cause problems, with the air valve slamming open and shut, depending on spring tension in the air valve spring. It basically acts as a cushion, but it *might* hurt MPG, but nothing else really.

Dorian
My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
Why insist on counting when the ring gear has the tooth counts stamped in?