Adjust your initial timing so you don't use the carburetor's curb idle screw to open the throttle plates to far to uncover the idle transfer slots. Start with around 16* initial timing to get the engine to idle around 950 rpms. If you don't get instructions with your carburetor go to Edelbrock's website for tuning instructions. You will need a vacuum gauge to tune the carburetor. Before installing the carburetor adjust the idle transfer slots to about .020. Here is the technical data on tuning your Holley 670 Street Avenger . http://www.holley.com/data/Products/...0219-3rev3.pdf
. Doesn't matter which carburetor you have both will have to be tune to your engine.