How much horsepower does a 307have with 4bbl and dual exhaust?

The horsepower of a 307 cubic inch Chevrolet small-block V8 with a 4-barrel carburetor and dual exhaust varied depending on the year of manufacture and the specific vehicle application. There's no single answer.

However, generally speaking, a 307 with those specifications would have produced somewhere in the 150-175 horsepower range. This is just an estimate; the actual horsepower could be slightly higher or lower. To get a precise figure, you'd need to know the exact year and model of the vehicle it was in. Factory specifications varied slightly from year to year.