What the difference between 455 Pontiac heads and 400 Pontiac heads?

The primary difference between 455 Pontiac heads and 400 Pontiac heads lies in their design and specifications, which affect performance and compatibility. The 455 heads typically have larger combustion chambers, allowing for higher displacement and more airflow, which can enhance power output. In contrast, 400 heads generally have smaller chambers and different port configurations, which can influence compression ratiOS and torque characteristics. Additionally, the valve sizes and flow capabilities may vary, making them suitable for different performance builds.