NGK BP5S Spark Plug Cast Iron Heads - Small Block - EACH

The NGK BP5S Resistor Standard Spark Plug is designed for reliable ignition and optimal engine performance. Its premium design and construction enhances spark efficiency, delivering smoother starts, better fuel combustion, and consistent power across all driving conditions.

The NGK BP5S is more suitable for small block engines with cast iron heads than the NGK BPR5ES due to its correct thread reach, built-in resistor, and wider design availability. 

Key Differences Between the E v S plug:

The 'ES' designation means a 19 mm (3/4-inch) long reach thread, which matches standard aluminium and modern aftermarket big block cylinder heads. The 'S' in BP5S often denotes a short 9.5 mm (3/8-inch) reach meant for older, shallow-reach iron heads, which will leave exposed threads in a long-reach hole and cause carbon fouling or misfires.