Where are my mixture adjusters!?! Q-Jet 4 Barrel Tag no. C-9625

[81GMCSierra1500]

Hello again, all,

I'm going though WAY too much fuel, just recently found out that my carb was barely even on the engine (no idea how or why), but now she's running way too rich, I found the idle speed adjuster screw next to the throttle pull cam, but where are my adjuster screws, looked high and frickin' low, and can't see them...
Any thoughts? It's a Q-Jet 4 Barrel tag number C-9625... Hopefully somebody can help, my local mechanic isn't answering his phone... -_-

[MountainGoat1966]

Look at the front of the carb, on the base plate below where you see the vacuum fittings.
Often, they had plugs installed over the adjuster screws.
A tiny drill bit and an easy out will remove the plugs.

[81GMCSierra1500]

Originally Posted by MountainGoat1966

Look at the front of the carb, on the base plate below where you see the vacuum fittings.
Often, they had plugs installed over the adjuster screws.
A tiny drill bit and an easy out will remove the plugs.

I appreciate the quick reply MG, Seeing as it's too dark to see much, I'll check in the AM tomorrow, but I do appreciate any input... THis carburetor apparently has a bunch of leaks, so she'll need replacing anyways, but I need to get a bit better mileage out of 'er :P

[MountainGoat1966]

Before you spend a herd of money on a new carburetor, it might be worth rebuilding.
There are two well plugs at the base of the primaries that usually start to leak.
Clean up real good and seal them with a tad of JB weld and let it set up completely before reassembling.
Usually takes a little filing to get the two halves of the carb to go together if the JB weld glob is too thick.
And check the base plate where the throttle shaft runs through it, if there's a ton of wobble it will need to have bushings installed.

[81GMCSierra1500]

Originally Posted by MountainGoat1966

Before you spend a herd of money on a new carburetor, it might be worth rebuilding.
There are two well plugs at the base of the primaries that usually start to leak.
Clean up real good and seal them with a tad of JB weld and let it set up completely before reassembling.
Usually takes a little filing to get the two halves of the carb to go together if the JB weld glob is too thick.
And check the base plate where the throttle shaft runs through it, if there's a ton of wobble it will need to have bushings installed.

Right... I Certainly must try that, if I have to upgrade regardless, I'll find a cheaper Re-Manned one of the same, either that or go to Edelbrock or something...

[MountainGoat1966]

If you end up getting an Edelbrock, get a fuel pressure regulator and put it in the line going to the carb, set it at 4.5 to 5 psi or you run the risk of flooding it and wasting gas.
Edelbrocks are good but are sensitive to too much fuel pressure and it's easy to over-ride the needle/seat and float.

[geezer#99]

Mixture screws won't change a bunch of leaks!
It's flooding!
Carb kit time.

Here's a rebuild link with a pic of those mixture plugs.
http://www.vetteprojects.com/kstyer/quadrajet_3.htm

[81GMCSierra1500]

Originally Posted by geezer#99

Mixture screws won't change a bunch of leaks!
It's flooding!
Carb kit time.

Unless you're talking Vacuum leaks, which is what's happening, not fuel leaks... But yeah... I just realllllllly don't want to have to spend 350+ on a new carb, when that 350+ could be going to bodywork & other stuff...

[geezer#99]

Buy a carb kit and come down Island!
I'll help you rebuild it!!

[81GMCSierra1500]

Originally Posted by geezer#99

Buy a carb kit and come down Island!
I'll help you rebuild it!!

G, that would be sweet! It won't be for a bit, yet, mostly because I landed a job, and I only go down once every 2 to 3 weeks, but that would be sweeeeeeet!

[Dead Parrot]

Something to check before rebuilding the carb is make sure the exhaust system is flowing freely. On my 75, one side of the OEM Y-pipe collapsed, forcing most of the exhaust through the intake crossover. This did bad things to the carb causing it to flood like yours is doing. Even if you now have dual exhaust, it might be possible that it happened in the past. No point in fixing the carb if the original causing problem still exists.

Make sure your rebuild kit includes a float. Some of those were a sort of weird foam stuff that could get fuel logged and quit floating.

[TylerW]

Not again....

First of all, step back from the "must have an Edelbrock parts store carb" idea for now. Just like in all these threads I've been reading, A. you have to use an adapter, B. if it has a hot air or divorced choke, you lose the use of that until you wire up an electric choke and C. you go from having a carb that can flow up to 750cfm of air to one that will flow 625cfm or so, depending on which version the parts store has on the shelf.

I have rebuilt many Quadrajets and they are not hard to rebuild and they run EXCELLENT afterward. I just rebuilt one for my '79 350 and it works like new, choke and all. However, like any carburetor, you have to install it correctly, run the vacuum lines correctly and have an engine that is not about to expire anyway.

The number you gave is not a valid number for a Quadrajet. The number you are looking for is on the driver side of the carb, on a rib running vertically, behind the linkage. Looks something like 17057223..for example.

The IDLE mixture screws are at the bottom front as mentioned.

I have many Qjet videos on my youtube, check them out if you wish to rebuild it and get it working good again. Otherwise, go to the parts store, get your carb and your adapter and have at it

www.youtube.com/whosaidtyler

[TylerW]

Also, being an '81 the idle mixture screws "might" be sealed under plugs but I don't think Canadian carbs had to do that. I also be that is a rebuilder carb and you got that number off the tag that is retained under a screw at the top. Just a guess.