[David Jones]

What a pain.
When the Qjet (79 Buick) is on the workbench, setting them to an equal starting point, even this blind 62 year old can put the screw driver in the tiny little slot and count turns.
Making final adjustments on the car? Running?
Jeeez.
The passenger side can be seen and fairly easily reached with one length screwdriver. Flashlight, screwdriver under the PVC hose into the screws cave, into the slot and a reasonable chance that you’ll actually verifiably turn the screw.
The driver side?
Makes. Me. Cuss.
Shorter screwdriver required. Radiator hose in the way. You can get a light onto the screw but that pretty much is where the screwdriver needs to be. “Did I really turn it?”

What do you do?

Are there longer screws?
Cut it off? Adjust. Crank it.
Special tools?
Magnets? Devining rods? Voodoo?

[abefromen]

https://www.ebay.com/itm/Carb-Adjust...sAAOSw1QxfypzN

[78w72]

guess it depends on the engine bay & things around the carb... on a 2nd gen firebird with no A/C & air cleaner off, mine are rather easy to get to & see in daylight, at night a light pointing at the carb is enough. i use a smaller tip ~6" long screwdriver & can easily see the tip insert into the screw & watch/count the turns... of course, bent over with my head down close to level with the screws. my q-jets are both cliff built with factory mix screws.

[steve25]

I don’t know if you can still find them but flexible speedo cable like screw drivers with slide over captured end covers use to be made by KD tools and others for doing this job in car, just like the ones that could had with a Allen wrench on there end for setting Dizzy points.

It might be helpful if you kinda do the same by slipping a short section of fuel line over the end of the screw driver you are using.

There’s also law against removing the mixture screws and using a hack saw to cut a cross slot in there heads
To make them into a better gripping Phillips head screw!

This type of small 1/4” drive ratchet is a very handy tool to have also for doing the job in the car by loading short length screwdriver bits onto.

[David Jones]

I’ve got a flex shaft drill and a burr, any harm in flaring the opening in the base a bit? From looking like a tunnel to something more like a funnel? Looking at this other base, I don’t see anything I’d hurt.

[i82much]

i have the same problem on the passenger side secondary idle screw on holleys, especially vac secondary. almost worth converting to two corner idle.

no idea what to do with a quadrajet, but i do feel your pain.

[steve25]

No harm at all to giving yourself more clearance in the base area, just dam good tape rags around the top side of the carb to keep from getting grinding shards from getting into all the important small passages in the carb.

[mgarblik]

The Lisle 55250 is my favorite idle mixture adjusting tool. It really works great. I discovered this tool when I worked at the Pontiac dealer in 1979-1982. When the computer controlled Q-Jets first came out, you adjusted the idle mixture screws by watching a Dwell Meter set on the 6-cylinder scale, essentially looking at the mixture control solenoid duty cycle. You needed two of these adjusting tools because you had to adjust both screws at the same time to get the correct idle balance. Because there was only one oxygen sensor, if you did them one at a time, you could easily have one side rich and the other lean unless you kept close track of the turns and so forth. I would take the tool and put it on the screw. Then mark a position on the handle with liquid paper. That gives you a good reference point. I think that will work well for you.

[NeighborsComplaint]

There are Quadrajet mixture screws out there that have a hex head or hex shank that you an use a nut driver on. There are also "Double D" tipped idle air screws and a flexible shaft driver with a bit to fit them.

[mgarblik]

Originally Posted by NeighborsComplaint

There are Quadrajet mixture screws out there that have a hex head or hex shank that you an use a nut driver on. There are also "Double D" tipped idle air screws and a flexible shaft driver with a bit to fit them.

The Lisle tool has both of those adapters. I believe the 79 Q-jet in question would have the hex shank. Pretty sure the double D started with the CCC Q-jets. You have to hole saw or hack saw the base and chip away to get access to those. No big deal either. Rochester supplied little dimples as a cut template on the base plate. Made a good living "tuning" those CCC Q-jets. Once set-up right, they ran well and got similar fuel mileage to their TBI replacements.

[Cliff R]

Double "D" with the flex shaft tool works best.

I sell long custom mixture screws for the later carbs with metric threads that are slotted drive and stick out about 1/8-1/4" so they are easy to turn.......Cliff

[Dick Boneske]

Or, you could use a length of rubber hose like we do on Tri-Powers. 1/4" ID works fine.

[David Jones]

Originally Posted by Cliff R

Double "D" with the flex shaft tool works best.

I sell long custom mixture screws for the later carbs with metric threads that are slotted drive and stick out about 1/8-1/4" so they are easy to turn.......Cliff

I called myself looking for longer screws Cliff. Are they pictured on your site?

[77 TRASHCAN]

Originally Posted by David Jones

I called myself looking for longer screws Cliff. Are they pictured on your site?

I think the all screws he sells are longer...

[carbking]

Originally Posted by Dick Boneske

Or, you could use a length of rubber hose like we do on Tri-Powers. 1/4" ID works fine.

X2

Some of the rubber hose has a stripe running the length of the hose. If the brand at your parts house does not, one may be painted on the hose.

The stripe may be "indexed" to determine how much that screw had been moved.

Jon.

[David Jones]

This old blind man should be able to see the screws up in their tunnel now.....

[David Jones]

I can now see what I’m doing when a mixture adjustment is needed. The mixture screw tunnel is now a much larger funnel. I also painted one half of the top of the screw so my nano second memory is challenged less.

[1968GTO421]

Thanks David for this thread and for your well done pics. Being even older than you, I can appreciate all this helpful info, appreciate it.

[Greg Reid]

What carb # is that David? I don't think any of my Q-Jets have those screws recessed like that.

[Cliff R]

"I called myself looking for longer screws Cliff. Are they pictured on your site?"

The picture isn't updated but the metric mixture screws are longer. I'm at least 2 days behind returning phone calls, been BURIED in them the past couple of weeks......

https://cliffshighperformance.com/pr...rings-79-later