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1986 Suburban with a Computerized Quadrajet?


1993Suburban
05-18-2009, 08:17 PM
Hey there, just bought a 1986 Suburban to work on this summer for a project. There is no engine in it right now, however I am getting a 350 Goodwrench engine that is sitting in a 1980 Chevy truck right now. I am buying the engine from the same person who sold me the Suburban. I have the carb that is original to the Suburban, and I will be getting the carb that is on the Goodwrench engine. The person I am buying from claims he disconnected the computer in the Suburban when he installed his built 383 into the Suburban. He since took the 383 out and is getting some work done on it so he can then put it into the truck which, at the moment, houses the 350 engine I am buying from him. He claims the engine will run without any of the sensors hooked up. There is no longer a provision for the O2 sensor in the exhaust pipe and I don't belive I will be getting the original computerized distributor. Now, I live in Idaho, so emissions wise this will not be a problem. But what I want to know is will the engine run without the sensors hooked up? I didn't even know the Quadra-Jet had sensors on it but apparently it did in the 80's. If anyone can shed a little light on the situation I would appreciate it.

1993Suburban
05-19-2009, 01:13 AM
Well I answered some of my own questions! The carb I have is NOT original to the Suburban. It was manufactured a year earlier and it is federal emissions compliant, not California emissions compliant. It seems after year 1981, electronically controlled Quadra-jets were installed on cars, and trucks WITH CALIFORNIA EMISSIONS. It has a plug on it, but no TPS. The plug on it is the accelerator pump solenoid, NOT a mixture solenoid, even though they are in the same location. As for the Suburban, I can't tell whether it is California emissions or not. Either way, it seems this carb will work on my 350 engine without the ECM or CCC or whatever it was called back then. This is good news! The carb seems to be reasonably clean and all linkages work freely, however it probably wouldn't hurt to overhaul it.

EDIT: I found some information at this link.

http://www.hotrodders.com/forum/modifying-electronic-controlled-quadrajet-150264.html

Also I looked up the carb numbers to help answer my questions.

toddman67
05-19-2009, 05:13 AM
Basically the computer is going to control the primary metering rods. The mixture control unit holds the metering rods down in the jets leaning the carb out for Idle. With out this hooked up you will run pretty rich at and just off idle. You can pull the aluminum plug from the air horn and play with the primary enrichment screw, but after a couple of weeks you'll be better off getting a carb designed to run without the computers assistance.

I suggest that you consider making a purchase of a new carburetor. Edlebrock makes a direct bolt on carb that would work great for your situation. I'm sure Holley has some too, I just prefer the edlebrock.

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