Now I may be mistaken here but if someone could guide me in the right direction it would be appreciated. This is my first carb'ed car all my others were TBI so I'm trying to diagnoss what I think is a problem.

When I push the throttle linkage all the way back the choke ontop of the secondaries does not open. Isnt the vacuum diaphram suppose to pull this open in order to feed the secondary barrels of the carb air?

When you turn the car on the diaphram just pushes out. No mater how much gas you give it, it doesnt come back in. WOT the choke is still close over the secondaries.

Where should I start to fix this? Diaphram? Or is there something I can adjust. Can anyone basically explain how its SUPPOSE to work?

 

On a Q-Jet, the flap over the secondaries is the venturi. Air flow through the secondaries causes them to open. The vacuum motor makes sure they close and do not open too quickly.

If you push them open with the engine off, you can see the throttle plates. Opening the throttle all the way should open the throttle plate but only if the choke is warmed up or you hold the stop away from the throttle shaft. The carb is designed to prevent the secondaries from opening unless the engine is warm.

 

Ah ok I knew I had to be over looking something. I'll check them tomorrow then.

 

The flap over the secondaries is the secondary air valve.

 

Is there a way to tune it for better throttle response?

 

You can adjust the spring tension as described in the Qjet tech article.

 

https://www.thirdgen.org/quadrajet