carb ??

[tigwelder]

was trying to adjust carb 0n 85 k20 Q-jet a little. turned idle screws in all the way and didn't make any difference.engine just idled.turn them out still no change.do i have a vacuum leak or ?

[rsandusky]

1: Verify no vacuum leaks
2: was it fully warmed up? If the fast idle cam is engaged it's not at curb idle
3: try backing out the idle speed screw. turned in too far starts to engage the part throttle circuit
4: hook up a vacuum guage and adjust to highest vacuum and then turn in it back in 1/2 turn

Why are you looking to adjust the carb?

[tigwelder]

it was up to temp.fast idle hasn't worked in the month i have had truck.the reason i was checking adjustment is because after it is warmed up i get grayish smoke out of right tail pipe, left side is ok.when i checked the idle screws the right side was out 4 1/2 turns,left 3 1/2. so when i turned the screws in all the way it didn't change the way it was running. i thought it would kill the engine. i backed the screws out 2 turns and it stayed the same.no vacuum leaks. so turning the screws in all the way or 4 turns out makes no difference.the truck idles good and i don't know why.i will turn the idle screw down and see if that helps adjusting the front screws.what do you think?

[Jims86tpisub]

Try closing the curb idle screw all the way, then run it back in 1.5 turns, then see if you get any response from the Idle mixture screws.