Outboard Motor Coils

[John G. Napoli]

>
>I just thought I would put my little bit of knowledge in here about the 
>spark plugs you mentioned. They sound very similar to the NGK plugs that 
>are used by MAZDA in some of their rotary engines. They are a surface 
>discharge plug that performs very well, especially in turbo-charged rotarys.
>The plugs used in the rotaries are SD-10 and SD-9 both made by NGK. 
>
>A while ago I was looking through the NGK catalouge and found that there 
>is quite a variety of heat ranges available in these types of plugs. The 
>usual designation is SD-xx where xx refers to the heat range.
>
>Hopefully this is of some use to the fellow list members !!!
>
>Regards,
>
>Rob Skala
>
>
>

Yes, these are NGK plugs on my boat.  Now both two-strokes and rotaries have
more power 'strokes' than four-stroke motors.  Is this significant?  What
does it mean vis-a-vis four-stroke engines?


Regards,

John