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-   -   Computer controlled quadrajet on an early 350 (http://www.hotrodders.com/forum/computer-controlled-quadrajet-early-350-a-222551.html)

4speed57 08-05-2012 12:02 AM

Computer controlled quadrajet on an early 350
 
I just picked up a quadrajet today for $10. After checking the numbers it came off a 1986 chevy truck. I've read and heard you can't run one of these on an older engine without problems. From what I'm seeing on the carb, most of the ecm crap is external. It looks like I could remove it all and just run a manual choke. After that wouldn't it be the same as an older carb?

One thing that caught my eye with this carb is the idle mixture screws aren't capped off. I've always noticed with the ECM controlled carbs, the idle mixture screws are inaccessible.

I want to order a $15 rebuild kit and have a $25 carb. Will this work on my early 350 Chevy?

Thanks for your time,

spinn 08-05-2012 07:30 AM

Does it have the double capacity accelerator pump? That was the problem it would reduce to the normal /half volume once it warmed to remp. If you left it disconnected you would have the incorrect pump shot.

Those idle mixture caps can be removed. It means its likey someone was adjusting it.

They work awesome on a driven vehicle. They can make as much power as any other carb of its size. Not like a holley is going to make more power just cause it is a holley. That is superstition and brand loyalty I havent got time for.

Another great carb is the old AVS.

LATECH 08-05-2012 09:02 AM

2 Attachment(s)
The CCC carb is the one in the picture.Part number 210 is the TPS , it provides the computer with feedback in regards to the throttle posistion.
Part number 225 is the mixture control solenoid. It wont control A/F ratio without a computer. If this is the carb you have, at best it will run pig rich, foul plugs and be a total PITA.
Get an older non CCC quadrajet.
Put that thing back on the shelf.

4speed57 08-05-2012 12:08 PM

Thanks for the replies guys.

LATECH, my carb is the same as the one in the picture. I figured there had to be some internal gizmos that control the mixture.

I have two of the carbs that are in good shape. Too bad I can't use them!

Thanks again!

Joe

joe_padavano 08-06-2012 12:41 PM

As Spinn noted, 1986 Chevy trucks could have used either the computer controlled CCC carb OR the dual-pump shot carb. The former is totally computer controlled. The latter is NOT, except for the pump shot solenoid. The look almost identical from the outside. Both have the two-wire electrical connector on the upper front passenger side of the carb. The CCC carb ALSO has the three-wire TPS connector on the front driver's side. Of course, inside they are easy to tell apart. The dual pump shot carb has conventional primary jets and metering rods. The CCC carb has the special spring loaded jet/rod assemblies and a solenoid that pulses them up and down.

You need to be completely sure of what you have. In 1986 the CCC carbs were only used on half-ton pickups sold in Calif. MOST of the trucks got the dual pump shot carb, so it is much more common. If you have the CCC carb, you're out of luck. The dual pump shot carb, on the other hand, can be made to run just fine on an early 350. The accelerator pump was set up lean for emissions, so the larger pump shot was only used when the truck was cold. If you recalibrate the pump shot, you can either leave the solenoid in place or put a plug in the hole in the float bowl. If you want to keep the dual shot capability, simply wire a toggle switch that provides 12v to the solenoid. The rest of the carb is conventional Qjet.

joeshovelhead 11-08-2014 12:14 PM

hi, thankyou for being here on this site! i am working with a new hottroder on his project... he just got a 1984 Z-28. our question is: MOST all of the the polution stuff has been removed or pluged off before zach got the car, how do we remove the caps on the carborater that cover the ideal mixture screws? this thing runs very rich??? is there anything else we should considder when trying to get this car to run "better than new"? thank you joe and zach

LATECH 11-08-2014 01:36 PM

Chances are the rich condition isn't an adjustment issue, nor wood that cure it. Likely though......missing components like the ECM and associated wiring/sensors are causing the problem. Also likely is that it also needs rebuilt.
You would be better off getting an earlier q jet(non electronic) and a distributor with advance mechanisms and running that instead.
If you have a 700r4 auto ,then the throttle pressure linkage for the trans becomes an issue as well. It needs to be hooked up and have the Correct GEOMETRY otherwise the tranny will burn up pretty quick

joe_padavano 11-08-2014 01:50 PM

Quote:

Originally Posted by LATECH (Post 2734714)
Chances are the rich condition isn't an adjustment issue, nor wood that cure it. Likely though......missing components like the ECM and associated wiring/sensors are causing the problem. Also likely is that it also needs rebuilt.

^^^^THIS!

The CCC Qjet CANNOT run correctly without the ECU and all the associated sensors connected and operating properly. Don't even bother to try. Primary side mixture control is done with the solenoid that pulses the position of the primary metering rods in the jets. If the ECU and wiring is disconnected, the solenoid defaults to the full rich condition. You cannot convert this carb to standard jets, you must replace it with a non-computerized one.

bentley81 11-08-2014 10:26 PM

I wouldn't use it.chance on burning hole in piston.i picked one up at junkyard just for test carb.probaly run real lean on high rpm.i wish there was a way to make them work.i like the qjets.but not worth taking chance on them electric ones with no electric to hook to

vpd66 11-09-2014 10:11 AM

Quote:

Originally Posted by joe_padavano (Post 2734722)
^^^^THIS!

The CCC Qjet CANNOT run correctly without the ECU and all the associated sensors connected and operating properly. Don't even bother to try. Primary side mixture control is done with the solenoid that pulses the position of the primary metering rods in the jets. If the ECU and wiring is disconnected, the solenoid defaults to the full rich condition. You cannot convert this carb to standard jets, you must replace it with a non-computerized one.

LOL I have used a CCC Quadrajet on a non-computerized engine. I converted it to use Holley main jets and it worked pretty good. It was for a circle track race car and I did all the testing on my street car. I wouldn't recommend it for street use has it will not get very good cruise fuel economy because it doesn't run the power valve with the needles in the main jets. For circle track and drag racing these work fine. I did this 18 years ago and have now been saving up some CCC Quadrajets has good non-computerized cores are getting tough to fine. If someone wants a circle track Quadrajet and doesn't have a core I'll build them a CCC carb and save the non-CCC carbs for street cars.

bentley81 11-09-2014 10:53 AM

Your right on that.only one qjet in whole junk yard, and it was computer type.I just love the sound of them when right.

LATECH 11-09-2014 11:49 AM

Maybe someone can design a controller that will run off the TPS and a MAP sensor only, tht will run the M/C solenoid and be decent for street car .
Or figure a way to run the ECM for said carb with just a few of the wires and make it work, and somewhat tuneable.
I am certain it wouldn't be optimal for mileage,....but if it could work well for cruise and the enrichment side of it......:thumbup:
A lot of otherwise useless CCC carbs could be used.

joe_padavano 11-09-2014 04:57 PM

Quote:

Originally Posted by LATECH (Post 2736130)
Maybe someone can design a controller that will run off the TPS and a MAP sensor only, tht will run the M/C solenoid and be decent for street car .
Or figure a way to run the ECM for said carb with just a few of the wires and make it work, and somewhat tuneable.
I am certain it wouldn't be optimal for mileage,....but if it could work well for cruise and the enrichment side of it......:thumbup:
A lot of otherwise useless CCC carbs could be used.

That's pretty much all the factory ECU does. These are pretty simplistic systems (hey, computers didn't have a lot of power when this system was designed in the late 1970s). The ECU reads TPS, RPM, VSS, MAP, and baro sensor. It also reads the Park/Neutral switch to control idle speed, but that's a secondary consideration. All the other wiring is for the emissions controls - evap canister purge, EGR, EFE, secondary vacuum break, and A.I.R. diverter valve. Assuming you don't care about the Check Engine light, all that stuff can be ignored (though keep in mind that these carbs and fuel maps are designed to take advantage of EGR at mid-RPMs and run lean under those conditions). The ECU functions that matter are M/C solenoid duty cycle and spark advance. There are BIN files available for playing with the fuel and spark maps on these cars. The ECU is not the same as the TBI computer. And of course, the ECU only controls the primary side mixture; the secondaries use regular metering rods like every other Qjet. The other problem with the CCC carbs is that for the smaller motor applications (305 Chevy and 307 Olds, for example), the the secondary air valves are limited to only open about 70 degrees. You need to file the stop to get them to open the full 90 degrees.

I'm surprised that you can't find more Qjet cores. There are hundreds at spring and fall Carlisle, and except for carbs with rare numbers, cores can be had for about $15. I've got a couple of boxes full of spares. Frankly, about the only thing I use the CCC carbs for is to swap the primary throttle shaft with the one on an early Qjet that I'm using with a 200-4R, so I can run the factory TV cable.

vpd66 11-09-2014 04:59 PM

Quote:

Originally Posted by LATECH (Post 2736130)
Maybe someone can design a controller that will run off the TPS and a MAP sensor only, tht will run the M/C solenoid and be decent for street car .
Or figure a way to run the ECM for said carb with just a few of the wires and make it work, and somewhat tuneable.
I am certain it wouldn't be optimal for mileage,....but if it could work well for cruise and the enrichment side of it......:thumbup:
A lot of otherwise useless CCC carbs could be used.

I would think a Megasquirt ECU could be modified to work with a CCC Quadrajet. Thats the only tuneable ECU i know of.

LATECH 11-09-2014 05:01 PM

Quote:

Originally Posted by joe_padavano (Post 2736842)
Frankly, about the only thing I use the CCC carbs for is to swap the primary throttle shaft with the one on an early Qjet that I'm using with a 200-4R, so I can run the factory TV cable.

I was thinking just exactly that earlier. Makes buying a CCC carb worthwhile ,at least for 10 or 15 bucks.


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