800 cfm Q-Jets.

[pitts64]

Might want to check Cliffs book and forum out. I have one of his carbs and it's fantastic.. http://www.cliffshighperformance.com/

[af2]

Just wondering

I've got one that I'm messing with. Idle is super rich. Because of the amount the primary butterflies are half open to idle. I've drilled the idle circuit some there's still I can drill. Do I keep drilling so I can cloee the blades or is there something else I messed up when putting the carb together?

Double check the primary metering rods didn't get bent then check and seal the metering well as it can and will leak just being peened over.
Running the big off road .490/512 cam with a quadrajet never had to go to far on the idle screw.

[mdabbott2009]

I used cliffs book to rebuild it. I'm going to open it back up and double check a few things make sure floats set right. Rods arnt bent. Then do some more drilling I followed his set up for a small block which Its goin on a big block just thought it eould be little closer then what I'm at now

[dave brode]

I used cliffs book to rebuild it. I'm going to open it back up and double check a few things make sure floats set right. Rods arnt bent. Then do some more drilling I followed his set up for a small block which Its goin on a big block just thought it eould be little closer then what I'm at now

It may run even richer at cruise on the big block. The larger engine will "pull" harder on the carb. Afaik, The idle circuit effects mileage more on a Q-J than on most other carbs. From what I've seen, idle circuit orifice sizing as per Ruggles will make for a gas hog.

Here is a good thread on the idle circuit;
http://racingfuelsystems.myfunforum.org ... ut430.html

Dave

[jmarkaudio]

This section has a bit of QJet info if you search a little.

http://racingfuelsystems.myfunforum.org ... m.php?f=26

[mdabbott2009]

Well i've read everything in those threads about qjets. Now if it would warm up some then fun couod start again

[motorvation2go]

Just wondering
I've got one that I'm messing with. Idle is super rich. Because of the amount the primary butterflies are half open to idle. I've drilled the idle circuit some there's still I can drill. Do I keep drilling so I can cloee the blades or is there something else I messed up when putting the carb together?

I had the same problem,called nozzle drip,blades are open just enough to start main circuit but lacking airflow causing the drip issue. On the older type qjet on the base plate in centre front there is a small plug. Remove it and there is a small screw inside it controls the bottom stop of the powerpiston and needles inside jets. On the later carbs its referred to as apt (adjustable part throttle) and adjustable from top. Anyway you can adjust the piston lower and stop the nozzle drip causing over rich idle. Alot of people dont know of this and grinds the small steel pin thats on the bottom of the piston but then you cant bring it back up if need be. I use the screw and using a rule on top of base plate there is a small steel plate thats just above the base level. Using the ruler and adjust it so its level and counting how many turns its easy to bring it back to spec if need be . I have the older type 70xxxxxx and newer 170xxxxxx qjets and i prefer the older type.

A bit off the original topic... my apologies.
The best way to reduce throttle opening (while still maintaining idle speed) is to add bypass air 'circuits' to the primaries.
A lot of Qjets had this feature from the get go.
Allows more air to make it's way [to down] under the throttle blades without pulling it through the venturis.
It stops the nozzle dripping thing.
Details on page 91 of Cliff Ruggle's book (even has 'pikkies').
Hope this helps.