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Holy cow, I feel dumb.

Discussion in 'The Garage' started by Sample, Jan 7, 2003.

  1. Sample

    Sample 1/2 ton status

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    Where in the heck are the carb adjustment screws at? I wanna see if I can get rid of my gassy smelling exhaust by adjusting the carb, but have no clue where the screws are. It is a stock Rochester 4bbl. Q-jet 4MC(something like that), on an '83 K5.

    Thanks,
    Chris
     
  2. Sandman

    Sandman 3/4 ton status Author

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    They are in the base on the front. Yours might have the plugs blocking them for emissions. You can take the carb off and drill them out. Those screws only adjust the mixture for the idle however. To change the overall picture you need to change out the rods or the jets.
     
  3. Sample

    Sample 1/2 ton status

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    Thanks Sandman.

    Now for more dumb questions. Where are these plugs/screws? Is there a good site all about Q-jets?

    thanks again.
     
  4. Sandman

    Sandman 3/4 ton status Author

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    They are on the front of the carb all the way at the base. If you see two round looking plugs all the way on the bottom, those are it. I dont know of any good sites. I went to the bookstore and got a book. Once you get the plugs out, You can buy a flexible looking tool from the parts store that makes adjusting those thing much easier.
     
  5. Burbinator

    Burbinator 1/2 ton status

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    A picture can be seen here. Also, another member has a site with some Q-jet information here.

    The adjusting tool can be found at Checker. It has a red handle (mine) and a 4" flexible shaft with a 1/4" hex for accepting different adapters. The one for the mixture screws looks like an inverted slot screwdiver. If you can't find one, I have one left over from my '82 Suburban that you can have...

    /forums/images/graemlins/burb.gif
     
  6. Sample

    Sample 1/2 ton status

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    Burbinator, thanks for the pic. I can say now that I don't feel as dumb as I did. the reason I can not find the screws is because my carb doesn't have those there. My carb looks exactly like the one in the pic minus the 2 spots where the screws are.

    Are you offering a full carb to me? If so, I will take you up on it. I can't afford much, so let me know. I am in Phoenix right now and can get it whenever you are free.

    Thanks,
    Chris
     
  7. Burbinator

    Burbinator 1/2 ton status

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    Sorry, I meant the adjustment tool... /forums/images/graemlins/smile.gif

    I had an old Q-jet about a year ago, but it is long gone...you wouldn't have wanted it! /forums/images/graemlins/grin.gif

    Is your carb an OE GM carb or aftermarket? Sometimes the holes are plugged with aluminum so well that it blends in with the base. Every GM and Edelbrock Q-jet I have seen has had screws or screws with caps installed.

    /forums/images/graemlins/burb.gif
     
  8. Sample

    Sample 1/2 ton status

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    Lol, thougth I would try at least.

    I am not too sure about the carb since I just recently started working on it and I am not sure what the previous owner did to it. However, it is stamped "Remanufactured by Holley" on it. So I am assuming it is not original.

    I guess I will look closely, are the hole flush with the carb, or do the screw ports stick out like on the pic?
     
  9. Burbinator

    Burbinator 1/2 ton status

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    /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif

    The holes are recessed into the base. My arrows were a bit misleading, I noticed...the ports sticking out are vacuum ports. The screws are under those ports on the driver side and under the fuel filter on the passenger side.

    If you look on the other link I posted, it has an exploded view that might better illustrate where they are.

    *EDIT*

    On the exploded view, the base (400) has items 420, 421 & 422 going in on one side...that is one mixture screw. Same for the other side, although it isn't shown.

    /forums/images/graemlins/burb.gif
     

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