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79 k5 carb help

  #1  
Old 12-22-2009, 10:17 PM
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Default 79 k5 carb help

i have a 75 k5 with a small v8 and a 2 barrell carb i am not too famailiar with carbs.there are 2 adjustment screws on the bottom of the front what are they and how do i adjust them .thank you
 

Last edited by mjchris; 12-30-2009 at 12:28 AM.
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Old 12-23-2009, 07:34 AM
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If it is the stock 2-barrel rochester carb those would be your primary mixture screws and you would adjust them by turning them. But what are you hoping to accomplish? What is your truck doing?

If you do not know if it is the stock carb, you may want to identify it by cleaning it up and getting the numbers off of it.
 
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Old 12-30-2009, 12:30 AM
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they are backed out so far that they are about to fall out ,and yes i believe it is the stock carb
 
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Old 12-30-2009, 01:52 AM
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Sounds like that baby runs pretty rich if the mixture screws are out as far as you say. They should have a spring on the outside to hold the final adjusted position by tension.
 
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Old 12-30-2009, 06:33 AM
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If these are the fuel mixture adjustment screws, they sound like they are out way too far. Typical base setting is 2-1/2 turns from seated.
 
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Old 12-31-2009, 03:05 PM
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We always tried to adjust them with a vacuum gauge to get the highest vacuum. There is an old rule of thumb method. Make sure everything else is to spec (timing, etc.) then screw them in until the starts to miss and back them out 3/4 turn. I agree. If your engine runs good the way it is, why fight success? Is there something wrong with the way ir's running?
 
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