Lodge HF (or other muti-electrode plugs)

[Simon.Gardiner]

OK, as Lodge were a reputable manufacturer unlikely to invest in something that was completely useless I spent a while asking the internet a few more questions.
In a nutshell, it seems the idea behind the multi ground electrode plug was to get increased service life (by spreading wear across multiple electrodes instead of just one) and possibly also reduce failure due to fouling by having alternative spark paths available. This is at the expense of performance as the single electrode design gives better flame propagation and combustion efficiency.
So, probably not the best spark plug to use in a two-stroke but might work OK in a marine lump that spends a lot of time just churning along.

SG

[cmfalco]

I spent a while asking the internet a few more questions. … possibly also reduce failure due to fouling by having alternative spark paths available.

As I wrote previously, multiple electrodes do not reduce fouling, because "fouling" is due to something (e.g. carbon) that provides a lower resistance path back to ground along the insulator than the path through air that results in a spark. If, instead, one of the four electrodes were somehow directly shorted to ground by "fouling," that would provide an even shorter path but, like carbon on the insulator, it also would short the other three electrodes.

As a general comment/caution, this present post is on the internet, so the reader has to decide if the information I just wrote is nonsense, or if the information Simon found on the internet is nonsense. Either way, it means there is nonsense on the internet, since we both can't be correct. My money is on my information actually being correct, but I would say that, wouldn't I?...

[nevhunter]

Just to mention another aspect. 2 strokes are pretty good at Whiskering Plugs. This is where a tiny thread of carbon forms across the Gap, shorting out the plug.. Sometimes it will clear itself if you are going fast enough. Otherwise you remove the Plug and even a flat blade of grass is enough to dislodge it, (pun intended) and you can go on your Merry way. Some plugs were made to be disassembled shown by having a Nut where the normal plug is swaged over permanently.. I've always carried a new plug with me on Old bikes and the tube spanner for it. Make sure it doesn't bounce around too much in the toolBox.. Nev

[Simon.Gardiner]

As a general comment/caution, this present post is on the internet, so the reader has to decide if the information I just wrote is nonsense, or if the information Simon found on the internet is nonsense...

Gosh darn, tarnation take those folks at Autolite - and to think they opened their article with 'One of the most misunderstood spark plugs in the industry is the multiple ground electrode spark plug.'
https://www.autolite.com/knowledge-base ... park-plugs

But even NGK (US) mention 'first used to aid in preventing carbon fouling....' Ye gods! At least they do go on to make more of development to reduce plug change intervals due to the more even dispersion of spark plug wear.
https://www.youtube.com/watch?v=53yfHLdn41k

In my professional career I've seen more than one misconception take root and become accepted as a norm even by expensive 'expert' consultants. It's always a long fight...

SG

[cmfalco]

accepted as a norm even by expensive 'expert' consultants.

It is highly unlikely either of those articles was written by an expert consultant. Almost certainly, they were written by English Literature majors who managed to bag jobs as "technical writers." Ideally, they would accurately translate into understandable language the technical information given to them by engineers, and ideally those engineers would understand the underlying physics in order to give accurate information to the writers. Ideally...

[nevhunter]

The Plugs Heat rating should certainly be given consideration as the idea of the temperature being sufficient to keep the Insulator free of carbon requires it. Colder Plugs for HOTTER motors. A cold plug has a short and fat insulator, which will carbon up if the Motor isn't worked. It shorts out readily and may be hard starting and Misfire till given a good squirt. Too hot a plug will cause pinging or detonation and engine damage. Cast iron Heads cause Pinging if the compression is high and the Motor is hot or you let out the clutch too quickly with lower octane fuel. Having the Mixture a bit Lean can increase the chance of pinging. Nev