1999 Mercruiser HI-Performance GM 377 EFI Engine Service Manual, Page 115Get this manual

1999 Mercruiser HI-Performance GM 377 EFI Engine Service Manual, Page 115

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377 CID6.2L ENGINES
1 Remove rocker arm cover2 Remove spark plug of affected cylinder3 Remove rocker arm assembly4 Install air line adaptor tool (J-23590) in spark plug hole and apply compressed