The Adjust-A-Jet bolts in between the metering block and fuel bowl. The Adjust-A-Jet does not affect the original emulsion characteristics or idle characteristics and will bolt on with little or no modification. The Adjust-A-Jet may be used on any Holley or modified Holley carburetor.
The Adjust-A-Jet is supplied with a chart that compares jet sizes to particular number of turns open, this is only to get the engine running, after that you no longer need the chart because you are making a rich/lean adjustment, instead of a jet change.