The closed chamber design of the 351W heads increases airflow to the spark plugs, enhancing engine performance. The 351W heads have larger combustion chambers than regular Ford heads, enabling the chambers to fit the larger plugs utilised in high-performance applications. The closed chamber design reduces the quantity of gasoline burned without adding any additional power, which increases the engine's fuel efficiency. The 351W heads have a larger inlet valve than regular Ford heads, which enhances air flow into the engine cylinder and raises the quantity of oxygen available for combustion. This lowers emissions while increasing the engine's overall efficiency. https://www.totalperformance.net.au/cylinder-heads-ford-302-351-windsor