Quadrajet too rich!

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Bennyt

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It's a 750 cfm carb on a 305... It's a little rich to begin with. Get yourself a Holley 600 cfm or Edelbrock if you can pass smog with one of those. Lean the af mixtures in and check timing.
Actually, I think its an 800cfm in truck applications. I believe the cars were 750cfm. I doubt a Holley or Edelbrock would pass emissions over a properly functioning Q-Jet. Holley is designed primarily for racing applications and the Edelbrock/ Carter/ AFB/ Weber is a decent runner but kills mpg.
 

Bennyt

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Good evening. I have an 85 c10 with a 305 in it. It's my dream since I was a child. The carburetor I've got is I quadrajet 17085226. I'm inquiring because I'm having a hard time passing emissions due to it's running too rich and, I don't know what else I can do to correct it. I'm pretty sure at this point I just need to change the jets due to the altitude. I live in Aurora Colorado and the altitude is 5,403 ft. I need help purchasing the correct jets. I'd really like be able to drive my dream truck legit but I can't get a registration until I pass emissions.
PLEASE HELP!

Did this vehicle pass emissions prior to your ownership in Colorado? Has something changed? Why do you think its the carb? Does the truck run well?
 

Snoots

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Get Cliff Ruggles book.
 

RaisedK5

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One thing that a few of my old cronies and myself years ago, did was not properly set the lean drop at idle. It can be hard on emissions carbs because of the sealed idle screws but it's a good place to start. If lean drop isnt set correctly you end up relying on the idle screw to keep it running at idle. This most times kicks the throttle plates open to far and ends up creating the rich condition through the idle circuit. Once i Iearned how to set mine my truck ran a ton better.. not sure if that's really the problem but it's an important adjustment. Also gonna want to check the secondary air door spring tension. If the secondaries come in too soon it will rich up.
 

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