CAUTION: This engine uses TWO DIFFERENT types of spark plugs. A total of 16 plugs are used. The plugs are mounted in two rows (banks). The upper row (5) is used on the intake valve side of the cylinder head. The lower row (6) is used on the exhaust valve side of the cylinder head. The upper row (5) uses Bosch Nickel Yttrium plugs. The lower row (6) uses Bosch Iridium plugs. DO NOT INTERCHANGE THESE PLUGS.
CAUTION: Do not attempt to clean any of the spark plugs. Replace only.
CAUTION: Due to tight clearances between UPPER row of plugs (5) and cylinder head, a conventional deep, thick-wall spark plug socket will not fit. Use a deep, THIN-WALL 5/8" spark plug socket for plug removal and installation.