Help With Carb Tuning
Help With Carb Tuning I have a 600 cfm edlebrock 4 barrel carb with two fuel adjustment screws, but I have so idea what they do and how to tune them, does anyone have any idea or helpful hints as to how to go about doing this? It's running rich and going through gas like it's cool 
. Thanks
. Thanks they're base idle air/fuel adjustment screws..turn in to lean out, turn out to richen up idle, turn them in until engine stumbles then turn out until idle stops rising then turn back in about 1/4-1/2 turn, the best way to adjust them is with a vacuum guage, in which case you would adjust for highest vacuum reading, all adjustments should be made at hot idle and engine at operating temp...after adjustments are made you may need to adjust idle speed, if you do you'll need to verify all adjustments meaning you might have to do it several times, timing will also need to be verified before closing the hood..good luck
Thanks for the input but how do I know which is which? Is one an idle screw and the other to be adjusted for driving? And would I hook the vacuum onto the fitting that goes to the distributor or....????????
basically, a good starting point is 2 1/2 turns out from bottom, when turning them in pay real close attention to "feel" when the screw is bottomed out, DO NOT OVERTIGHTEN THEM, each bank maybe need different fueling so the screws may not be exactly the same position, dont worry it's normal, there are 2 screws because each primary bore has an idle circuit that it uses
Awesome so start out 2 1/2 turns from bottom and start to lean it out from there by screwing it in slowly? Then set the timing again? Where does the vacuum gauge come into play. Thanks for the help.
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yes and yes, if the carb is new and i hasnt been monkeyed with that adjustment may be pretty close, depending on the motor....... connect the vacuum guage to a manifold vacuum source, watch the guage while makin adjustments, tune for highest vacuum on the guage, then turn the screws in about 1/4-1/2 turn, this should be best lean idle setting...like I said adjusting those screws will have a little bit of an effect on everything so you'll need to verify idle speed and timing once you're done.... anytime
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Verdad Gallardo Since I don't an rpm gauge should I just adjust the idle by ear? This process will probably have to be done at least three times along with adjusting the timing right? The carb was brand new when installed and I know for a fact it's 2 1/2 turns out because the "guy" at autozone set it for me.
