If anyone has any advice it would be great to hear your thoughts.

Camaro 1980 Z28 350L w/ Rocherster Quadrajet Carb

Car had been running fine, however, rich and burning through petrol - it was suggested that the carburetor required an overall.

Being a project car I wanted to tackle the overhaul myself. Long story short, result it was placed back on the engine and temporarily running fine. Turned out there was a fuel leak coming from the accelerator pump, easy fixed - readjusted the float which stopped the leak.

Now here's the problem... carb was placed back on engine and this time the car will not stay running for me to adjust the idle of the carb. Example, turn the engine over and I have to keep my foot down on the gas pedal to keep the car running, as soon as I remove my foot the engine cuts out.

I've attempted to adjust the idle mixture screws to resolve the issue. Details online state that they should be screwed all the way in and then wound back 1-1/2 to 2 turn turns each. From here you should then be able to make some minor adjustments to have the carb running smooth (and also adjust the idle etc). My issue.. I can't keep the engine running for long enough to do this.... Adjusting the idle mixture screws is effecting the idle rate, however, still no go keeping the engine running..

It's been suggested that I've "missed the sweet spot" and need to keep adjusting the mixture screws as there seems to be an issue with the primary fuel being supplied to the carb?

If you can help or have any suggestions, please post away... need or want more info please let me know!

- Alex

 

Here's what you do....remove the carb, take it into the outback, and then find a kangaroo to stomp it into the ground. Then buy a Holley! Can you tell I don't like Quadrajunks very much?
OK, but seriously:
It ran before you rebuilt it, although rich, but now it doesn't. You need to retrace your steps, because something went wrong somewhere in the rebuild. Are you sure you got the float level set correctly?
If you can keep it running long enough, spray some starting fluid around the base of the carb to check for a carb-to-manifold gasket leak.
Is your throttle shaft a sloppy fit in the carb base. They're prone to wear which can cause fuel/vacuum leakage problems.
Generally though, a vacuum leak with a carb would give you a higher than normal idle as opposed to a non-idle issue.
Since we weren't looking over your shoulder, it's hard to say if it's something you did when you rebuilt it, but it would be safe to assume so. Is everything else working as it should; choke, secondary metering rods, etc?
To keep it running so you can at least get your head under the hood to mess with it, crank in the curb idle screw (front drivers side corner of the carb) to crack open the butterflies and speed up the idle.

 

Hi Mate!

Thanks for the reply, sorry for the late follow up..

So I ended up taking the carb back off and retracing my steps.. I found that the secondary metering rods weren't seated properly, so that was fixed up...

I'm pretty confident that the vacuum is sufficient for the carb at the moment..

I tried something to keep the car running which was to manually keep the choke valve closed upon start up and then gradually let it open a 1/4".. this worked, however, as soon as I let it warm up and little and try to let the choke valve open the engine just stalls again..

I've noticed that the choke coil lever is missing from where the thermostatic coil is? This was actually missing when I was taking the carb apart in the first place.. I'm still unsure how the car was working in the first place without it!!

I'm going to head back out there again today to see if I can make any progress...

 

actually the q-jet is one of the best carburators ever made. the problem is that people dont know how to tune them to perform for their application. the q-jet is the only carb that can be adjusted all the way up to a 800cfm carb. they are actualy beter than a holley or an edelbrock and so forth.

here is a site that will answer any q-jet tuning questions you have just look around a bit and i know you will find what your looking for.........
http://www.florida4x4.com/tech/quadrajet/index.php

 

If everything else is adjusted correctly, that would mean your carb is running too lean.
Will the engine idle fine if you manually open the throttle a little?
Then I do need to ask a "duh" question. Have you cranked in the curb idle screw (throttle linkage stop) to speed up the idle, or is that not the issue?