Quadrajet issue

[ron mattson]

Take a wooden match or small wood skewer
And stick down air vent and on top of primary
Metering rod hanger and mark height to top
Of vent tube, then fire car up and repeat this
Will tell you if the hanger is functioning while
Running.

[Robert Simpson]

After you do what Ron stated. Disconnect the accel pump, with it running. If it get crisper and idles better, you are rich and vise versa. Dean told me that one, it works. Also you might have to increase the diameter of the passages behind the fuel mixture screws in the baseplate. Example they are .079" open them up to .089". Just a thought.

Robert

[Mike Taylor 3601]

A trick I have learned the hard way is needle and seat sometimes will leak slightly,but they won't run fuel out vent tube like holley,so it's not as obvious,will drop idle a few hundred rpm,and will bog few feet out because runs over. To check this I remove top and hold float pivot down with finger and put fuel pressure to it fuel level will come up shut off float,then watch for about a minute if leaking fuel level will slowly rise,I have got to where I just go ahead and test all of them I work on.

Another thing to look @ is primary butterflies there is idle circuits that have slotted opening the butterflies have to line up with these slots,adjust idle speed screw to line them up,if engine idles too slow then you have to start drilling holes in butterflies to increase idle speed.

You can also slighly choke w/hand if idles has vacc. leak or blocked idle circuits,too lean,etc
Qjets are more sensitive to vacc leaks,low vacc than holley.
I would also check timing could be retarded too much @ idle.
I would just go over basics first which you'll probaly do first anyway
You can find drinking straws that will fit down vent and push metering rods or watch them operate
Mike Taylor 3601

[nhramnl]

Things I would check:

Fuel pressure - it can't exceed 7psi. If it does, the pressure can blow the needle off of the seat and the carb will flood. Look for fuel dribbling from the booster clusters and listen for irregular "hissing" sound.

Float level - can't be too high, or the carb will dribble fuel into the venturis and the carb will flood.

Secondary hanger and rods - make sure the rods are fully seated in the orifices with the car at idle. The air door must be completely closed (not adjusted to provide additional idle air) because it can pick the rods up and allow secondary fuel.

Make sure the inability to achieve a stable idle is actually due to richness and not simply the result of a vacuum leak. Use the carb cleaner diagnosis method.

[Alan Roehrich]

Is the carburetor rebuilt by a professional, or is it a remanufactured carburetor purchased from a parts store?

[tj310]

Heavy float due to absorbed fuel ---Trevor

[buzzinhalfdozen]

Alan ,carb was off the shelf rebuild to my knowledge. Has stock fuel pump on it though that's no real indicator of correct pressure. After reading the posts I realized I've got a few old tools from back in the carb days that may help on this, thanks for all the input now I have to see when he's gonna bring it over. BTW I tried directing him on checking the PP from the air horn however it's difficult over the phone. Thanks again and I'll update after I've looked at it myself. Man it's been a loooong time since I've seen a carb wish I had a better memory.

[Alan Roehrich]

Joe, if it came off a shelf at a parts house, I'd almost bet they've thrown away most or all of the Rochester metering parts, and they've used lead slugs to block the air bleeds in the main metering body.

I used to work for Mayo and Shrum in Nashville, we were the top carburetor shop in this area. It was company policy to refuse to work on remanufactured carburetors unless the work was on a per hour plus parts basis. I don't think I ever fooled with a remanufactured Q-Jet from any remanufacturer that had the original Rochester metering parts, or that did not have the air bleeds plugged. As a result, they all ran at about 8% CO on a 4 gas analyzer, otherwise known as pig rich.

You have to know what metering parts belong in the carburetor to fix it right, but if you have the gaskets, you can at least take it apart and knock the plugs out of the air bleeds in the main metering body, and that should at least make it somewhat useable.

If I can help, or answer any questions, send me an email or a PM, I'll do what I can.