carb adjustment

[fris_94]

i had my truck in the garage the other day and the guy that worked on her did some adjustment to it and im just wondering what he did. on the side of the carburetor is a screw that had never been adjusted before. the screw itself was capped with a plug and enclosed in the carburetor. he had to cut away the metal to get at the screw. the screw is on the left side around th bottom when looking at it from the front of the truck. the truck is a 1983 c10 L6 250. 2bbl carb