Carburetor Trouble!!!

[pjpj1979]

Hey guys I have a Holley 600 cfm on my sbc 5.7 and for some reason it's idling really high. I have the idle screw backed all the way out and it's still idling to high. What can I do to get my idle to normal? I try adjusting the air/fuel mixture screws but they really make it run worst. Is there something else I'm not doing right? Is there any other adjustments I can make?
Thanks!

 

[pontiacgp]

what about the choke and the high idle adjustment, is that sticking?....and you backed the idle screw out but if the fast idle is stuck the adjustment you made will have no effect. Is there a gap between the idle screw you adjusted and the arm for the butterfly?

 

[pjpj1979]

Where is the high idle adjustment located? and yes there is a gap between the idle screw and the butterfly arm but is still idles high?

 

[pontiacgp]

there shouldn't be a gap where the idling screw is but that tells you its an issue with the high idle setting....look on the other side of the carb and there should be a cam and an adjustment screw. That cam is probably stuck and if you just gently push the arm down while you open the accelerator it should go down and release the fast idle. You might want to turn the adjustment screw you turned out back in to where you think it was so the car will idle and then adjust it to what you need. You could spray down the choke mechanism with carb lube to try to free up the high idle mechanism

 

[pjpj1979]

Ok I'll try that out...Thanks alot buddy!!!

 

[pontiacgp]

it's a pretty common problem on carbs so most of us ole guys have seen it before..if you have an electric choke make sure you have 12 volts going to the choke terminal or the choke won't shut off. Just remember if your car is running ok and an idling problem shows up all of a sudden it's not the idle screw that will cure it. Another thing is before making any adjustments try to find the source of the problem so you don't create another problem with an adjustment you made.

 

[pjpj1979]

now I adjusted the air/fuel mixture screws already...so if I fix the problem then I have re-adjust the screws again right? Is there a certain way to adjust the screws so my carburetor works correctly?

 

[pontiacgp]

I think on a holley the starting spot for the idle mixture screws is 3 turns out and adjust from there. You can attach a vacuum gauge and adjust each idle mixture screw to achieve the highest vacuum to adjust them. If you going to stick wot a holley you might consider buying a book for your particular carb. The books are not expensive and it can help you out maintaining the carb and it'll give you the proper specs for adjustments