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Discussion Starter #1
Anyone out here know how to adjust the air mixture on this Quadrajet; part #17080204 3349CPM, it decodes to a 1980 49 state, chevy & A/T. Have it on my 1967 327 4 spd. but where I think the adjustment screws are there seems to be nothing. Bought this used and not sure if somehow the screws are gone or not. I've attached a picture of the front of the carb, note where you think the screws are there area marks where maybe something was. If that's where they would be and I'm not crazy how and where do you get parts for it.

http://zteiyw.blu.livefilestore.com/y1pYVwQs03-ZaErls_2-yznQv6jVcDEg0KAojugavTcP_H-OeVADqWV422hXrJMHJCyM-TtXQ17tYyZxUC8FF-7SQ/carb 004.jpg
 

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At the front corners just above the c in edelbrock on your intake and in the same place on the other front corner. Looks like someone alreadt chiseled out the plugs. You need a special socket to adjust them.

Dan E.
69 SS396 4spd. 4.10 posi. x66 coupe
 

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Discussion Starter #3
That's what I thought, do you know if they originally screw type fitting or different type fitting and where do you get parts for 1980 quadrajet nowadays?
 

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Isn't that an engine specific emission carb? That's a battle that's hard to win.
 

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Discussion Starter #5
It's not the computer one, but I have no idea what this is because I can't find info on it, the manual it decodes to doesn't look like this one. Should I be running this on my 67 - 327? New 268 cam, 2.02/67 cc heads, headers, RPM Manifold. Looked like a good deal on ebay...but nothing is ever to good to be true :confused:
 

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The idle mixture screws are conventional, except that the end is shaped like a small oval and there is not screwdriver slot. Take a piece of tubing, maybe 1/4" brake line or similar, and form the end of it to make a socket. You can then adjust the mixture screws with your new tool. You can also remove the screws and saw a screwdrive slot in the end, if you wish.
Good luck.
 

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It's not the computer one, but I have no idea what this is because I can't find info on it, the manual it decodes to doesn't look like this one. ...
You're right - that's not the 'computer' controller E4ME type introducted on many 80 California sold cars and light trucks :noway:
It's a pretty rare variant used in 79 and 80 California sold trucks and on some other special applications.
The model type is M4ME - it has some of the provisions used on the later "E4" series, but it doesn't use any of the electrically controlled systems - like the fuel rate control, enrichment solenoid and others.
It was introduced to replace the 60 & 70's 4M/4MV/4MC types.
(note: for future reference, 4M = Manual Choke / 4MV = Remote mounted [also called 'Divorced'] auto choke / 4MC = carb. body mounted [integral] choke system)

The Idle Screws originally were sealed with factory installed 'plugs' over them.
Someone busted (by the looks in the picture) them out, rather than following GM's procedure for removing them ...
The Screws themselves are a special drive type (inverted "clutch" ) to prevent 'Shadetree' types from messing with the factory idle settings and renduring the emmissions out of compliance.
You can make a home-made tool for turning/tuning them out of an 1/8~3/16" piece of (soft) copper or aluminum tubing @ 2~3" long - use the "Tang" end of a file (the tapered end that goes into the handle) and shove it into the end of the soft tubing, it may be necessary to hold the tubing in the vise and pound the file in a little with a small hammer. Once you've got the tang into the tubing @1/4" or so, squeeze (or hammer) the sides of the tubing closed on the tang to form an internal shape that fits over the screw end - viola, you now can adjust them ...
The 'Tool Trucks' also sell a socket to fit them.

There's really nothing wrong with that carb as long as it's well built, jetted/rodded/assembled correctly and is adjusted/tuned right.
It's not miss-matched to your engine size wise and can easily deliver the amount of air/fuel needed for good performance if properly built and tuned.
Rochester carb.s will deliever excellent performance in most applications - just takes a little extra time to get to know and love them :thumbsup:

Hope this helps.
 

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It looks like that carb is an EGR carb. Not a good choice for a performance style Q-Jet. That additional large port just above and to the right of that blue plug is for EGR. From what I have read, they are horrible for performance and can not deliver the performance you are after. I suggest going to your local salvage yard and getting a Q-Jet from a 75-83 Chevy truck and rebuilding it yourself. Saves money and you know it's done right. The 75-83 have the APT screw that allows for super fine tuning of your part throttle air/fuel mixture.
 

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Discussion Starter #9
Thanks everyone for all your advice. Except for the vacuum advance & pcv hose I have plugged all the other ports. The carb does sound fine when running although haven't taken it for a ride yet, seems to be running rich as I'm getting some smoke out of exhaust. I'll make the tool and give that a whirl.
 
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