If you are tuning for cruise efficiency, pay attention to the transfer slot opening. .020 or less is good, idle feed restrictor mods, ect

Here are some good links to read:

http://www.carcraft.com/howto/ccrp_0507_carb_tuning_tips_tricks/viewall.html

http://www.carcraft.com/howto/116_0501_carbs_tips_tricks_cheap/viewall.html

http://www.chevyhiperformance.com/tech/e...eage/index.html