Re: champion or ngk spark plugs
Sorry, I would call that link (URL begins with "members....." ) a technical OPINION not a technical explanation
The article in my link, which is a direct link to the article on the author's own website hence the URL, is one of a series, mostly but not exclusively, on outboard engine technology written for the (Australian) Instutute of Automotive Mechanical Engineers (IAME) member magazine - ?The Automotive Engineer?.
I apologise for not prevously stating the source of the article.
The facts are that OMC recommended only the Champion Q series plugs with all their engines with CDI.
Q series plugs are low resistance inductively suppressed plugs.
Only the Z series from NGK are inductively suppressed.
NGK plugs have bad reputation when used in Johnson and Evinrude outboards which I suspect is not because there is anything wrong with NGK plugs, au contraire, but because in the absence of inductively suppressed NGK plugs until relatively recently, resistor plugs were recommended and used with sometimes disappointing results.
The hard line approach would be to respond to all questions about plugs by saying
use only the engine manufacturers recommended plugs! In the case in point this amounts to QL77JC4 or QL78YC.
I prefer the softer approach, particularly with questions originating in the UK where Champion plugs are not so readily available, namely to suggest the nearest equivalent NGK plug. In this case BZ7HS-10.
You dismiss the article in my link as an "opinion" rather than a techincal "exlanation" I, therefore, look forward to reading
your explanation for the reasons OMC recommended only inductively suppressed plugs for use with their CD ignition systems.