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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: dvdswan on April 28, 2014, 08:04:51 pm

Title: mixture screws for quadrajet carb
Post by: dvdswan on April 28, 2014, 08:04:51 pm

so my gas mileage is so/so, nothing like my blazers was and realized my truck is burning rich.  I went to adjust the mixture screws and one of them is stuck.  any suggestions on how to get it loose without damaging it?  the passenger side screw goes in and out but not sure if its doing anything and the driver side is stuck.

Title: Re: mixture screws for quadrajet carb
Post by: bd on April 28, 2014, 08:20:00 pm

Moisture may have gotten to it.  Take the carb off & remove the base plate.  Soak the dickens out of the screw from both sides with PB Blaster (2-3 days if necessary).  Work the screw back and forth to remove it - use a propane torch if needed to increase penetration of the lubricant.  Clean the threads thoroughly.  Blow the passages out with carb cleaner and compressed air.

While you're in there burnish and epoxy the aluminum secondary fuel well plugs with some Devcon Plastic Steel.  Do the same with the lead primary well plugs.  And, check the float for absorbing fuel with a light squeeze between your fingers.

Title: Re: mixture screws for quadrajet carb
Post by: dvdswan on May 13, 2014, 11:43:41 pm

thanks for the tip bd. 

I took the carb off and noticed it was just plain nasty.  so I tore it down and soaked everything in carb cleaner.  picked up a rebuild kit and put it all back together and took the truck for a test drive.  its like a brand new truck,  started up and purred like a kitten.

thanks again bd.  and yes the mixture screw was corroded.

Title: Re: mixture screws for quadrajet carb
Post by: bd on May 14, 2014, 10:34:43 am

A nice running truck is a great reward.  Glad I was able to help.