CAM PERFORMANCE QUESTION

The idea with alot of overlap, both valves open at the same time is to help pull in a fresh charge of air and fuel in stock heads and/or heads that don’t flow well out the exhaust side. That’s why some cams have more lift and duration on the exhaust side as well. This all gives you a rough and lopey idle as some exhaust is pulled back into the intake manifold at low rpm. It will also raise the power band of the motor limited by how well the heads flow. Passenger car heads just are not racing heads, kind of a band aid to get more go.