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Holly carb adjustment



I have a 327 in my 68. not orig specs its been built a bit not by me. my problem is at idle it runs rich. i believe the carb is a 650 W/vacuum secondarys.my question is what is the setting for the idle mix screw. Haven`t had a chance to check the float level. i think the idle mix might be my problem, any ideas is appreciated. Thanks
Provided the carburetor and engine are in good condidtion (other than the rich-at-idle condition) and the fuel pressure is at the correct level, here is the procedure:

First, set the float levels.
Second, set the curb idle to specification.
Then, turn each idle mixture screw lean in 1/2 turn steps, alternating on each side. At the point where the engine idle speed slows a little. Turn each screw rich about 1/4 turn.
Finally, reset the curb idle.

If you find that the idle screws are unresponsive, the carb either needs to be rebuilt or is the wrong carb for the application.

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