comeau331

Hey all, I have a ccQjet on a 305 in a 86 trans am. The idle is never consitant and seems to adjust itself... the choke closes too tight and doesnt seem to open all the way. Its an elec choke and its getting 14.4v when the car is running. is there an adjustment for this? I'm trying to nail the idle down as well, i know theres two idle screws, one on passengers side and drivers side. which one should be used for idle? Im thinking one is for cold idle and the other is for warm? I want to get this carb working properly but i'm about ready to replace it with a completely mechanical carb... the car is impossible to start when cold without keeping your foot on the pedal... ive read on here 1/8th of an inch is about where the butterfly should be when cold but I have no idea how to adjust it... Thanks for the help!

five7kid

iTrader: (14)

I take it you haven't seen this sticky:

https://www.thirdgen.org/forums/carb...e-rebuild.html

Doom86

Read through that sticky for sure. Don't do the daft thing and go back in time with technology.

The idle screw is at the front drivers side of the carb towards the base and accessed from the front. All 3 of my carbs the idle screw is torx headed. Make sure you have no vacuum leaks when setting it you should be able to kill the motor adjusting it. These 20+ year old cars with their maze of vacuum lines are prone to that which is why I mention it.

You are right the idle does change the ECM has some control over it and it's manually adjustable. Mounted on the front top front drivers side is the device (can't think of it's "name") it has a hex head tang that pushes out to the main throttle linkage under certain circumstances, turning on the AC will make it engage. It is adjustable by turning the hex head of the tang.

The high idle adjustment is the one on the passengers side.

The choke thermostat can be adjusted all you need is to drill out the rivets and put little nuts/bolts in their place, it takes all over 2 minutes to do. With the motor cold you want to turn the choke thermostat just passed where it makes the choke valve snap shut. It probably wont need turned "too" far from how it's angled now.

Now once you've got that sorted you need to adjust the choke pull-off so that it cracks the choke valve open 1/8th of an inch when the motor is cold started. You need a phillips head screw driver to do this. The choke pull-off is the diaphragm looking thing on the top front passengers side of the carb with a short single vacuum line and a linkage going to the secondary air valve. The screw you are going to adjust is on the top of it pointing towards the windshield. You don't need to start the car just when the motor is cold blip the throttle linkage to close the choke valve and push the choke pull-off down to check how far it opens the vale and adjust accordingly.

naf

iTrader: (7)

Before going too crazy with any adjustments, ensure your choke pull off is good. With the vac line off press the plunger in and hold your finger over the opening for the vac line. The plunger should stay in until you release your finger. If it fails, replace it.

comeau331

The choke pull off is good. I've read that sticky but its almost like its in another language. Funny cause I'm a wiz with cv carbs haha but thanks a ton guys I understand it much better now! I'm going to give adjusting the thermostat a shot, it sounds like that could be why it doesn't open or close enough. The idle is loping and I'm only using egr, pcv and one line for the distributor and I'm not sure if its a carb issue or just a vacuum leak. All of the lines are plugged off with tight fitting bolts and the intake manifold bolts are tight as are the carb bolts. Do I have this right: the high idle adjust controls the idle speed when cold/choke on and the curb idle controls the warm idle as once its warm a blip of the throttle drops the idle from fast to curb. And the phillips screw is a 'fine' adjust for how much the choke flap closes?

Doom86

Almost right the phillips screw on the choke pull-off is to adjust how much the choke valve cracks open when the pull-off gets vacuum from the motor starting/running. If the engine is cold, or you manually engage high idle, but don't start it and close the choke pull-off with your fingers you will/should see it open the choke valve 1/8th inch as if it were just started up.

You can engage the high idle cam even when the motor is hot, not sure if you know this. It's the green lower lever under the choke pull-off with 2 other levers resting on it. If you push up on it with your finger while you open the throttle with your other hand it will engage. To disengage push it and the 2 levers sitting on it back down, you don't want to try to start a hot motor with it closed.

The choke thermostat adjust how much the choke closes and opens and how fast. Once you drill the rivets out you'll see turning the part the 12v plugs into will adjust the valve. Set it when the car hasn't run for 5-6 hours, I prefer over night though. Make it snap shut and turn just a bit passed that. Yours may be too tight, or too far passed shutting atm.

Naf is right though make sure it really needs adjusted, measure and observe first. It's always good to have this basic knowledge of the Qjet though it's come in handy more then once for me.

comeau331

Ok, I got the choke to close about 1/8th of a inch with vacuum applied to the pull off. it started really easy which is a first since ive owned it! idled around 1200, took it to Tim Hortons and sat at the drive thru for a good 15 mins. total round trip was around 30 mins of city driving. came back and checked the choke butterfly and it was only about half way open. I know I have power to the choke heater. Would adjusting the choke heater element itself fix that? I used the screw on the choke pull off to get it to close the right amount. Also the car now HATES hot starts. The starter sounds like its chugging and I had to hold my foot to the floor to get it to fire. (i'm guessing cause of too much fuel and not enough air being that the choke is partially closed...)

five7kid

iTrader: (14)

Typically the choke thermostat is tabbed so it can only go in one spot.

Verify nothing is binding or gummed up in your linkage. If it moves freely, then you most likely need a new choke thermostat.

naf

iTrader: (7)

I vote for new choke thermostat as well. It should certainly be opened completely within 30 minutes.

The factory thermostat is tabbed but the handful of replacement stats I've bought didn't have the plastic tab and could be adjusted. Set a replacement stat with the plug at 6 o'clock and go from there. Should open completely within five minutes or so AND remain open while the engine is still hot...that's why your car won't start hot now. The choke is still closed when it should be open.

Doom86

This is a good point try carb cleaner on all the joints and levers and see if it's just getting stuck. It does happen, I had a Qjet that wouldn't kick down from high idle unless you tried 50 times and a couple shots of carb cleaner on the linkage for the high-idle did it right.

The choke valve it's self is very easy to move or should be at least. Can you open it completely with your hands? Opened "all the way" is when it's straight up.

Also the choke pull-off adjustment isn't to close the valve it's to open it a crack when the motor first starts.

The tabs never stopped me from adjusting either of my Qjets choke stat. And to replace the choke stat you have to drill out the rivets anyway so it's worth it to try to adjust it. If it's not able to find that medium between closing all the way and opening fast enough I would definitely replace it. The thermostat is coil loaded so when you turn it, it tightens the coil making it close tighter/soon on cold start but that also makes it take longer to open when it's running. If your linkage isn't binding up yours sounds too tight.

comeau331

So after playing around with it some more it seems that the choke thermostat itself is the culprit. I let the car run for a hour or so and the choke only opened halfway, to the second step on the cam. I could manually push it down and the idle would drop and allow curb idle adjustment but as soon as the throttle moved it would kick back over to the fast idle cam. I'm guessing that the choke isn't getting hot enough so it causes resistance on the linkage, kicking it back onto high idle. Any thoughts? Is there a way to bench test the heater coil itself?

PaPaROC

Good thread. Any more info? My qjet has beening rebuilt and tuned, so I was told. Choke works, you can see the linkage move. First start takes while,sometimes gotta pump it. Aftr thatt it starts on first turn of the key. I was just gonna replace the elec choke and call it a day.

naf

iTrader: (7)

Are you giving it two good pumps on the accelerator prior to trying to start it cold? This sets the choke and provides a booster shot of fuel.