I would like to ask for your help to adjust my CCC quadrajet from 84 Firebird


Advance set to 6 degree with four wire connector disconnected
New TPS set to 0,5 V
Stop lean mixture screw set with 1.304" gaging tool
Rich mixture stop screw set to obtain 4/32" total plunger travel
Idle Air bleed valve set with 1,756" gaging tool (home made tool)
Idle mixture screw preset 3 turns

New catalytic converter
New oxygen sensor, (AC Delco)
New coolant temp sensor
New TVS for EFE (EFE close when the engine is cold and open when the engine is hot)
Choke work (Close when the engine is cold, and full open when the engine is hot)
All vacuum lines are news
Smog pump blows into the exhaust manifold when the engine is cold and in the catalytic converter when the engine is hot
I change the throttle shaft bushing (primary and secondary)

When I restart the engine (hot), the idle is 800 rpm and dwell 30 : after 10 sec idle increase to 1500 rpm and dwell to 50.
Adjust idle mixture screw don't change the idle and the Dwell
Adjust IAB change the idle (completely thightened, engine stop)

Maybe vaccum leak ? but spray brake cleaner on gasket and vaccum line doesn't change the idle
Bad sensor ?
In France, people who don't know the CCC carb and prefer change to basic Edelbrock

Some ideas ?
Thanks !

 

Yes it could be a vacuum leak. Check all the hoses etc.

Also, the idle speed isn't set by way of the screws, all of the time; there's a solenoid on the side of the carb that the linkage comes to rest against. You can screw its plunger in and out to change the idle. Some of those can be set with a wrench, others you just have to use pliers.

Look closely at the little link on the choke side of the carb, that sets the high idle. It's supposed to just fall from high to normal idle when the choke comes off. If it's sticky you'll have high idle all the time.

The idle mixture screws don't really do anything on that carb. Set them to about 6 turns out and leave them alone.

The car will run FAR better with more timing than that. Experiment; you'll find that somewhere around 12° of advance will wake it up in a big way. It will also raise the idle, so get that sorted out first.

 

Thanks for the quick reply.

The solenoid on driver side don't touch the throttle linkage.
I've an other question about the throttle plate (butterfly ?) When the idle screw on driver side is complety loosened, primary et secondary plate are not perfectly closed. I can see a bit of light between throttle plate and body. Is it normal ?

About the high idle linkage. When the engine is cold, choke close, idle is at 1500 rpm. After choke open, if I press throttle pedal briefly, the idle speed doesn't go down

 

A sliver of light is normal.

Staying at 1500 after the choke is open sounds like:
Also, I totally agree with this....

 

I change the throttle shaft bushing (primary and secondary)

You need to go back and reset the throttle plates so that all four plates show no light (or as little as humanly possible).
Great work so far - don't give up. Please stay with this.

 

I took over the work and started from zero.

Fast idle set to 2nd step good and the throttle plates. Here's the best I got

Primary :



Secondary



Now fast idle is 1500 rpm and push throttle decrease idle to 900 rpm in drive. And the idle screw had an impact to idle

I try 12 degree of advance and 6 turns to mixtures screws : look bad, engine is very hot (cat is red like hell) and idle not smooth.
The last settings are :
- 8 degree of advance (four wire connector disctonned)
- mixtures screws set to 4 turns
- IAB screw set with 1,756" gaging tool (I don't understand what is the role of this screw ??)

I get 25 dwell and test drive is good but idle is a bit jerky. Engine hesitate at the beginning of acceleration. Afer rpm easily increase.

 

Hi ! I'm still stuck with the carburator...

Cold start, choke, high idle are good. But I can't get 30 dwell when the engine is warm.
When I restart the engine (hot), the idle is 800 rpm and dwell 30 : after 10 sec idle increase to 1000 rpm and dwell to 50.
Adjust IAB or idle mixture screw don't change the idle and the Dwell. But If I press throttle, dwell go to 30, when released throttle, dwell return to 50...

I try many combinaison of timing, IAB and idle mixture screw setting. With ou without EGR, canister control valve. No good result

For now, I'm back to square one with these setting :Advance set to 6 degree with four wire connector disconnected
New TPS set to 0,5 V
Stop lean mixture screw set with 1.304" gaging tool
Rich mixture stop screw set to obtain 4/32" total plunger travel
Idle Air bleed valve set with 1,756" gaging tool (home made tool)
Idle mixture screw preset 3 turns

I don't know where to look anymore

 

I finally succeeded to get 30 dwell ! But car run very bad, no power...

I unplugged EGR, all canister vacuum. Only connected brake booster, vac sensor and PCV.
In canister control valve, I found lot of fuel. It is normal ?

I control leak in the carb. Well plug are waterproof. Float level is good (3/16)

When I star the engine (hot), the is 800 rpm, dwell 30, voltage o2 sensor 0,35 V : after 10 sec idle increase to 1000 rpm and dwell to 55. Voltage o2 sensor 0,9 V
If I create vacuum leak (unplug PCV), dwell descrease to 45, no more.

The only way to get 30 dwell, is to set idle mixture screw only 1 turn out. And refine with IAB. Voltage o2 sensor drop to 0,4 V
I get the same result with or witout each vacuum line.

If I understand correctly, car run too rich and ccc react. But I don't understand where the excess fuel comes from.....