Topics: 20May 6, 2015 at 3:26 pm #15440quote Pappy:
Nice, thanks for the link. Gonna give it a thorough read-thru
Topics: 8May 7, 2015 at 12:58 am #15452quote thepetrolist:
The chance of four brand-new spark plugs – made by two entirely different manufacturers – being ‘bad’ out of the box is pretty slim. Of course, in a two-cylinder motor, all it takes is +one+ bad plug to make things go awry.quote :
All I can tell you is that there most certainly +is+ an answer, and with the proper knowledge and instruments, it could more than likely be found. But I sure as heck can’t tell you, not from where I sit, way out here in the cheap seats.. 😉
And again, I’ve simply had crap luck with both Bosch and Champion, in all but a few previously-described situations. All plugs pretty much look & feel alike, but there’s some very serious and subtle science going on in those things.. a wide-world of trade secrets, I’d wager.
US Member - 1 Year
Topics: 22May 7, 2015 at 1:39 am #15457
I’ll try to explain what happens if you use plugs that are too hot. I have experienced this on two motors.
At full speed the plugs get to hot and the mixture pre-ignites resulting in a drop of rpm to a much lower speed. Then
since there is less heat the plug cools off and the motor starts running faster. On a 3.5 Chrysler air cooled motor it cycled over and over.
On a Johnson A-50 the cycles were less clear but it did not run well.
On the Chrysler I had inadvertently installed a H10C instead of the correct H8C.
On the A-50 I was simply experimenting. I tried D9s, D14s, D16s and D21s.
Ended up using D16s.
Topics: 5May 7, 2015 at 11:47 am #15473
Scott, very true. Using the recommended plug should work every time unless there are any of the other issues evxident. I will make one additional comment, the newer Champion plugs with the siffix "C" for copper, don’t work nearly as well as the ones with the suffix "J". I found that the NGK plugs recommended for replacement of the J 6 J work very well.
Topics: 31May 7, 2015 at 8:42 pm #15488
In the "good old daze" of sloppy sand castings, loose tolerances, and poorly refined fuels & lubricants, the recommended spark plug was only a sugestion. Some of our apposed cylinder antiques ran best with a different heat range plug in one cylinder. Many were damaged by over advancing the magneto. Things improved with better aluminum alloys and the uniformity of die casting. Even so, some of the Johnson "HD" and "TD" models had vapor lock problems in hot weather. The third port on these mounts the carburetor right next to the exhaust manifold.
The designated "J" Champion sparkplug had the side electrode end over the center of the center electrode. This was said to give a more "open" spark for better ignition in two cycle engines. I always file my new plugs back like that. I figure it can’t hurt. For one thing the way electrons gather on a flat surface makes it easier to jump from a sharp edge. For another thing, the edge gets hotter and wears down faster. A worn sparkplug will always have rounded edges. A little filing there can extend it’s life.
. . . . . 😉
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