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#1064956 - 01/30/20 03:13 PM Computer controlled quadrajet  
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LRS Offline
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LRS  Offline
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Gainesville Ga
Hello, Im new to this forum and new to these carburetors. I wrench on my own stuff for the most part. My wife inherited a 1986 monte carlo ss. Its pretty much bone stock with 65k miles on it, a 305 in it. Her grandmother bought it new and its been stored. The story was it needed a transmission and some dude had been tinkering with it years ago. . I got on running and found the issue with transmission was the tv cable had a broken latch where it mounted in the bracket up top, so the whole thing was just moving. Causing it to shift erratically. I fixed / adjusted that and it now shifts good. The choke pulloff was unplugged. I plugged it in and it seems to work. It closes and opens the choke, but its not right. When i start it cold, it will not idle. I have to sit with it untill it warms up and then it will idle but only at about 800 rpm. It never fast idles. Any insight on how to properly adjust this carburetor is appreciated. Ive taken it to 2 local shops and they wont touch it. Id rather keep oem carburetor on it if possible since the entire car is original. Thanks!

#1064957 - 01/30/20 03:41 PM Re: Computer controlled quadrajet [Re: LRS]  
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Buick Runner Offline
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Dharma station 1 the Hydra
Possible that your fast idle cam is sticking. There are two idle speed adjusting screws. The one ypu can easily see on the driver side is fof the curb idle which should be 600 RPM in drive. The second adjusting screw is on the passenger side for the fast idle when the engine is cold and the choke is closed. The fast idle speed should be 1,000 RPM. Before you start the car, you need to fully drpress the gas pedal to the floor then release to close the choke and set thd idle cam on the fast step.

Most modern mechanics are not trained and lack the tools and ewuipment to service carbs or anything pre OBD2. Our cars are like Model Ts to them.


SBC powered 1987 Regal with TES headers, ZZ4 intake, ZZ4 PROM chip, mini starter, THM2004R, 2500 stall converter, 2040 cam, CCC system, and 3.73 posi rear.

2008 ex NPS P71 Crown Victoria, cop motor, cop shocks, cop brakes, and Jmod.

Never argue with an idiot.
They will just drag you down to their level and beat you with experience.
#1064962 - 01/31/20 02:34 AM Re: Computer controlled quadrajet [Re: LRS]  
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LRS Offline
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Gainesville Ga
Thank you. I will check it out more this weekend. What does the phillips head spring screw on top of choke on passenger side actually adjust?

#1064963 - 01/31/20 05:17 AM Re: Computer controlled quadrajet [Re: LRS]  
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PB86SS/87LS Online beer
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New Berlin, WI
Not surprised some shops aren’t willing or able to work on a carb especially Q-Jet, but surely there are some options if you ask around. Some places still might have an “old timer” or someone who has experience or even a place that works on muscle cars.

A good source is Doug Roe’s book on quadrajets if you want to learn and be hands on with them: https://www.amazon.com/Rochester-Carburetors-Revised-Doug-Roe/dp/0895863014


-86'SS 383 CCC QJet- BRF 2004r-8.5" 3.42 -313/344@RW - 13.35 @103
-87'LS 350 MAF/SD TPI- CRF 2004r-7.5" 3.42 -248/340@RW - 14.55 @ 96
-81'Grand LeMans Safari Wagon 3.8 2bbl/200C/2.73
-07'TBSS Stockish daily driver
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#1064965 - 01/31/20 11:08 AM Re: Computer controlled quadrajet [Re: LRS]  
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LRS Offline
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Gainesville Ga
Thank you. Yes, I may as well learn it. This car is a family thing my wife was given from her deceased grandmother, so its not going anywhere. I will be the one maintaining it. It is a great future restoration candidate. Its in overall good condition. Just needs TLC. I put some 17” torq thrust on it that I had left off a former project and it looks good. Paint is faded and the air dont work. Needs a little interior work. Ive got 2 other projects in the works now, so it will be a little later before I go all out on the ss. I’ll probably be asking alot of questions on here.

#1064968 - 01/31/20 09:31 PM Re: Computer controlled quadrajet [Re: PB86SS/87LS]  
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LRS Offline
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Gainesville Ga
Ordered the book. Thanks

#1064970 - 01/31/20 10:42 PM Re: Computer controlled quadrajet [Re: LRS]  
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mmc427ss Online content
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That part on the side of the carb for the choke is the choke pulloff. Sometimes the diaphragm inside rupture, leaks. Connect a vac hose to it and using your mouth pull a vacuum on the pulloff. It should retract with vac, and hold vac. Place your tongue over the end of the test hose and see that it holds vac.
Bob

#1064971 - 02/01/20 05:13 AM Re: Computer controlled quadrajet [Re: LRS]  
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Buick Runner Offline
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Dharma station 1 the Hydra
It is the adjustment for the choke pulloff which you should check. Push the pulloff plunger all the way down and use a rubber band to hold it down, or use a Mityvac vacuu hand pump. Next check the gap between the top of choke blade and airhorn using a 1/8 drill bit as a gauge tool.


SBC powered 1987 Regal with TES headers, ZZ4 intake, ZZ4 PROM chip, mini starter, THM2004R, 2500 stall converter, 2040 cam, CCC system, and 3.73 posi rear.

2008 ex NPS P71 Crown Victoria, cop motor, cop shocks, cop brakes, and Jmod.

Never argue with an idiot.
They will just drag you down to their level and beat you with experience.
#1064990 - 02/03/20 01:16 AM Re: Computer controlled quadrajet [Re: LRS]  
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86ttop Offline
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If you think you need to have the E4ME gone over, I recommend www.customrebuiltcarbs.com I have had two done there for different cars and they both came out great, Click on my link and give them a call!!


Leo Paugh
It's not an attitude, it's just the way I am.
POW*MIA
You are not forgotten
If things improve with age, I must be approaching magnificent. thumbs
#1065003 - 02/03/20 10:03 PM Re: Computer controlled quadrajet [Re: LRS]  
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Lederach, PA
Also, look for a copy of the factory shop manual. It is blue and is called 1986 Shop Manual Caprice Monte Carlo El Camino. There are several pages covering the emissions controls and details you would need if you want to rebuild the carburetor yourself. You will need some specialty tools and standards to disassemble/reassemble the carburetor, and to set some critical adjustments.

#1065005 - 02/04/20 02:44 AM Re: Computer controlled quadrajet [Re: LRS]  
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Buick Runner Offline
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Dharma station 1 the Hydra
You will also need an analog dwell meter and use the 6 cylinder scale to set to fuel mixture dwell.


SBC powered 1987 Regal with TES headers, ZZ4 intake, ZZ4 PROM chip, mini starter, THM2004R, 2500 stall converter, 2040 cam, CCC system, and 3.73 posi rear.

2008 ex NPS P71 Crown Victoria, cop motor, cop shocks, cop brakes, and Jmod.

Never argue with an idiot.
They will just drag you down to their level and beat you with experience.
#1065019 - 02/04/20 09:08 PM Re: Computer controlled quadrajet [Re: Buick Runner]  
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LRS Offline
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LRS  Offline
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Gainesville Ga
When I cold start it, it runs rough and I have to stay on the accelerator until it warms up. If I do let it die, most times the choke closes up and floods the carburetor. Then the only way I can get it to start back is manually open the choke by hand. Im sure its got to do with the choke. Car runs great after I get it up over about 120 degrees. Which choke adjustment are you referring to the one on top or the one underneath?

#1065026 - 02/05/20 10:39 AM Re: Computer controlled quadrajet [Re: LRS]  
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Richie Cat Offline
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Lake Ronkonkoma, N.Y.
LRS look at this picture. There are two things that effect the choke operation.
The gold can back of carb, is the pull off and the black covered part in the middle is the electric choke spring.
If the gold can doesn't hold vacuum, it's no good.
If the electric choke doesn't have 12 volts to it, it won't open.
I suggest using Google to understand the operation of both.

https://www.ebay.com/itm/1985-1986-Chevrolet-Pickup-Rochester-Quadrajet-Carburetor-V8-/182869713487

Last edited by Richie Cat; 02/05/20 10:40 AM.

83 SC, 355 w/TPI
#1065034 - 02/06/20 02:00 AM Re: Computer controlled quadrajet [Re: LRS]  
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86ttop Offline
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Brooksville, Fl
That is not a pic of the carb for an 86SS, the choke pulloff in an 86 is on the front of the carb on the same side.. The OEM Part # for the 86 SS Carb is 17086003


Leo Paugh
It's not an attitude, it's just the way I am.
POW*MIA
You are not forgotten
If things improve with age, I must be approaching magnificent. thumbs
#1065035 - 02/06/20 04:14 AM Re: Computer controlled quadrajet [Re: LRS]  
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Buick Runner Offline
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Dharma station 1 the Hydra
Originally Posted by LRS
When I cold start it, it runs rough and I have to stay on the accelerator until it warms up. If I do let it die, most times the choke closes up and floods the carburetor. Then the only way I can get it to start back is manually open the choke by hand. Im sure its got to do with the choke. Car runs great after I get it up over about 120 degrees. Which choke adjustment are you referring to the one on top or the one underneath?


Sounds like the electric choke may not be working or is out of adjustment. May also want to check the float hight, float sinking, or sticing od leaking needle valve.

The choke adjustment I mentioned is the top one with the phillps screw. MCSS Qjets only have a front choke pulloff, a rear pulloff won't clear the EGR valve.


SBC powered 1987 Regal with TES headers, ZZ4 intake, ZZ4 PROM chip, mini starter, THM2004R, 2500 stall converter, 2040 cam, CCC system, and 3.73 posi rear.

2008 ex NPS P71 Crown Victoria, cop motor, cop shocks, cop brakes, and Jmod.

Never argue with an idiot.
They will just drag you down to their level and beat you with experience.
#1065038 - 02/06/20 11:32 AM Re: Computer controlled quadrajet [Re: 86ttop]  
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Richie Cat Offline
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Originally Posted by 86ttop
That is not a pic of the carb for an 86SS, the choke pulloff in an 86 is on the front of the carb on the same side.. The OEM Part # for the 86 SS Carb is 17086003


I picked that just to show the difference between the two parts.
I'm sure if the book is ordered and read he'll learn from there.


83 SC, 355 w/TPI
#1065056 - 02/07/20 02:31 AM Re: Computer controlled quadrajet [Re: LRS]  
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86ttop Offline
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Leo Paugh
It's not an attitude, it's just the way I am.
POW*MIA
You are not forgotten
If things improve with age, I must be approaching magnificent. thumbs

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