I have recently done dome tuning on an Edelbrock Carb on a mild street engine and thought I would share what I found. I used a wide band O2 sensor to tune the carb and changed idle screws, Main jets, Rods, and secondary jets.
Many people tuning EFI think that they need to use a wide band O2 sensor to keep the fuel ratio very close.
The engine I tuned with a carb runs so well after being tuned that you would think that it is EFI. As a side note, a half turn of the idle screw resulted in a ratio change of 1.0. With such a good running engine, I found that the fuel ratio would vary from 16:1 down to 11.5:1. At a constant cruise, the Fuel ratio will jump around from about 15.8 to 14.2. This is quite a wide ratio for constant speed and throttle. At higher throttle openings, the ratio would stabilize until at full throttle the ratio only varied +/- .2. As a comparison, EFI running open loop can run within +/- .2 of desired everywhere, and run right on the money at full throttle.
In light of this, I must say to many EFI "experts" that need to run a wide band O2 on an EFI car to make it run "right" is totally unnessesary.
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