Mercury 3.9 Spark Plug?

[lucania67]

Hi, a friend of mine owns a mercury 3.9 (not sure of the year) its an older model 60s for sure. Does anybody know which replacment spark plug would fit this engine and what the fuel gas mix is?
Thank you

 

[Laddies]

Re: Mercury 3.9 Spark Plug?

You will need the year pre 66 used J8J and later L9J they are different reach plugs both have been superseded to newer numbers.