holley off.. qjet tuning help needed

[RootBreaker]

Ok guys.. the holley is off of my truck now...
qjet is on... i dont know anything about these...

fire truck up and it runs at 3k rpms.. so high idle screw.. where is that?

qjet for reference is the first pic in this thread..
http://coloradok5.com/forums/showthread.php?t=296424

i dont know what the device is on the left.. (passenger side of carb).. up high.. that screw....
is that the high idle setting?

now when i start it... and it is @ 3k.. i hit the gas and then it stumbles till stall.. so wont idle.. i know the truck isnt warm yet...

 

[paratrooper307]

Check to make sure the idle adjustment screw is backed out. On my Qjet it is located on the driver's side ahead of the throttle linkage.

The stumbling could be timing, mixture, or choke issues. Incorrect timing can also make the engine idle high (Though not generally 3K high). Best I can suggest is check and verify each potential problem and eliminate them one by one.

That screw you're talking about looks to be a choke adjustment, but I'm just taking a stab at that one..

 

[TerryD]

Idle screw is on the drivers side, parallel to the ground. High idle screw is on the passenger side, buried down in the choke mechanism. You'll just have to get a light and go looking for it.

 

[wazzabie]

Take your idle mixture screws in all the way and then out 2 full turns as a starting point. You need to set both the high and low idle screws. First set high idle to the specified rpm on a cold engine. Then after high idle kicks in then set low idle to the specified rpm. Then using a vacume guage to get the highest vacume reading while adjusting your 2 idle mixture screws by 1/4-1/2 turns. You may then need to reset the high and low idle screws.

This is assuming that your float is good and set correctly.

There are 4 screws

the two idle adjusting mixture screws in the front. this mixes the air fuel / lean vs. rich
the high idle screw (when engine is cold)
the low idle screw ( after engine is warm)

 

[y5mgisi]

Subscribed.

 

[RootBreaker]

thanks guys..

yeah i have the idle screw out all the way...
it is the high idle i have to figure out..

i have no clue what that green thing on top with the screw is on the passenger side.. i did adjust that up a bit not knowing what it did..

ill try this hopefully tonight...

 

[y5mgisi]

How bout this,

 

[wazzabie]

The green thing if it is plastic may just be the factory cover. IT is rare to find those as most just take them off and junk them.

You will need to take it off. Also when you check the vacum you want to check using the lower manifold vacum. A good spot is the vacum going to the tranny if you have an auto. It is on the back of the engine.

First set the idle screws out 2 full turns after bottoming them out.
Set the fast idle first just by moving he bolt. You need to set up an rpm guage. Fo ran HEI this just goes on the tach outlet and the other to netural. Turn the high idle untill you get the rpm.
Then set the low idle after then engine has warmed and come off high idle. You will see it come off when the idle lever moves down.
Once you get the high and low rpms set then set the idle mixture screws (the two in the front) untill you get the highest vacume reading.
then check you rpms for your high and low idle