Thread: Adjusting the air and fuel screws?

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Hey guys i have a 72 chvelle and i have a 350 with 4- bolt main,stock pistons,mild cam, edelbrock streetmaster intake and a carter afb competition series carb.? my question is what is the correst postion for the idle,fuel, and air screws. i took a spark plug out and i noticed it was a grayish white color. it idles high but when its in drive it idles low and soounds like it going to die. i was going to try to time it but there are no numbers on the harmonic balancer. this car is a relly nice car but the engine is driving me crazy. i'm only 17 and duing all off the work on my own, but i would apperciate all the suggetions and ideas to my questions, thanks for taking the time to read this.

There would not necessarily be numbers on the harmonic balancer, usually just a timing mark. The numbers for the advance are normally on the pointer. I use a timing light with the advance knob on the back of the light, just line up the 0 mark on the pointer with the notch on the balance and read the advance on the dial.

hi. if you have a tach that you can hook up then you can reset the air\fuel mixture this way. bring eng to op temp . adjust idle to around 600 rpm's. back out both screws from bottom to about 2 1\2 turns.at this point one at a time screw in until motor changes rpm (lower) back out to obtane smooth idle. continue to other side . readjust idle to around 600 rpm adjust again the same way . reset idle screw to factory spec's for car and done good luck

Hey guys thanks for all the suggestions.

Using the tach is fine, but you''ll get a better setting using a vacumn guage. Vacumn guages are not very expensive and most auto parts store have them. With the engine not running hook it up to manifold vacumn, the tee where the power brake vacumn line is attached, and adjust for the highest reading. You should be able to get some where around 15 to 20 in of vacumn. When you get the highest reading back it down about 2 ins.