My spark plug confusion

thunderroad

Chief Petty Officer
Joined
Jun 19, 2005
Messages
417
69 Merc 160 2497444 with Pertronix ignition. I'm wanting to change plugs. According to NGK it needs a BR6ES. I've read opinions that when you add Pertronix to an older engine, you should use a one step colder plug. Any truth to this or should I stick with the other one?
 

thunderroad

Chief Petty Officer
Joined
Jun 19, 2005
Messages
417
Re: My spark plug confusion

I couldn't find where they made a reccomendation as to spark plugs. They did say something about being able to gap plugs .005 wider. I would assume they stay out of the spark plug thing because it would look bad to say..."Buy our product for $89...but you'll need different plugs". The reasoning given for the colder plug opinion (which I'm neither agreeing or disagreeing with) was something to the effect of "hotter plugs could possibly cause detonation or pre-ignition that may damage an older engine more easily than a newer one". My thinking kinda runs along the line that an older engine probably won't produce as much power (heat) and is also more likely to foul plugs..therefore it appears to me that the standard, hotter one would be better.
I dunno what to think. Just thought someone might have had a real world experience to pass along.
 

Fishermark

Vice Admiral
Joined
Oct 19, 2003
Messages
5,617
Re: My spark plug confusion

I've done a couple of engines with the Pertronix swap and have never had an issue with the plugs. I simply use the stock AC Delco MR43T plugs and they work great. (I don't know if that is the plug you need - it just happens to be the ones that I used on my engine - both before and after the conversion with no problems).
 
Top