Mknupp
Member
5.7 mercruiser alpha drive. Spark plug on one cylinder blows off porcelain after running above 2500 rpm.. compression good , heads have been redone, new carb and fuel pump, timing is spot on....no clue as to why this happens, also no water in the suspect cylinder, temp reads normal... only thing that hasn’t been done is manifolds and risers, however temps are normal and no water ingestion evident...completely stumped on the cause?...