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 Sparkplug reading 
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Joined: Sat Feb 09, 2013 10:46 pm
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Sparkplug reading via our late friend, Shrinker.


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Sun Apr 21, 2013 5:09 pm
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Joined: Mon Apr 08, 2013 11:38 am
Posts: 44
I almost posted a thread asking about plug reading the other day.

Seems there are different opinions on how to read plugs out there, so this is great!

Thanks!

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Mon Apr 22, 2013 10:55 am
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Joined: Wed Feb 20, 2013 11:38 pm
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Larry Meaux has a short read on plug reading.
http://members.uia.net/pkelley2/sparkplugreading.html


Mon Apr 22, 2013 11:27 pm
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Joined: Fri Mar 22, 2013 6:23 pm
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Location: Newcastle, NSW, Australia
It never ceases to amaze me in this game how many different opinions/ways to do things there are. . and each (to its creator/owner/believer) is clearly correct and the others are incorrect. .

Case in point the above linked article of Larry Meaux saying that the porcelain won't accurately reveal air/fuel ratios, yet the guys over in the Nitrous forum on YB swear by the 'fuel ring' on the porcelain as the best indicator of mixture.
(http://www.yellowbullet.com/forum/showt ... p?t=567313 is a good example of this).

Who is correct? Is the 'fuel ring' deal more applicable to nitrous tuning? Is it less relevant on an aspirated engine? (Larry Meaux doesn't indicate what style of engine his article applies).

Larry's article also discusses the 'heat' line on the ground strap as an indication of plug heat range, but doesn't at all mention ignition timing?
Won't advancing the ignition timing put more heat in the chamber and move that line, and conversely pulling timing will move the line in the other direction?

EDIT: not trying to sound like a smart arse here. . it reads that way when I read it back but I'm honestly asking, as it seems the theories at least somewhat contradict each other??

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Tue Apr 23, 2013 12:07 am
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Joined: Wed Feb 20, 2013 11:38 pm
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Maybe the heat and timing mark are the same. As we change timing, don't we change temps that the plugs see. So that mark is an indication of multiple characteristics involved in making heat.


Wed Apr 24, 2013 11:17 am
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Joined: Mon Feb 18, 2013 5:11 pm
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A few quick thoughts on "Reading" Spark Plugs:

- Different brands of Spark Plugs will read differently. For example trying to "Read" timing will differ from an Autolite to an NGK plug.

- Different brands of fuel will read differently as the additives and colors will leave different color on the plug itself.

- Remember that the plug is just one tool, looking at your O2's, cylinder bores, exhaust ports etc will all help you.

- Tune to what the engine wants not a specific look or color of the plug...


Fri Apr 26, 2013 4:52 pm
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Joined: Wed Feb 20, 2013 11:38 pm
Posts: 403
CarbGuy wrote:
A few quick thoughts on "Reading" Spark Plugs:

- Different brands of Spark Plugs will read differently. For example trying to "Read" timing will differ from an Autolite to an NGK plug.

- Different brands of fuel will read differently as the additives and colors will leave different color on the plug itself.

- Remember that the plug is just one tool, looking at your O2's, cylinder bores, exhaust ports etc will all help you.

- Tune to what the engine wants not a specific look or color of the plug...

Yeah, I think it's easy to get up in chasing numbers and losing track of what makes the engine happy. I spent 3 days on a dyno back in the 80's and walked out of there with less horsepower, but much better numbers. That was probably the best thing I learned from those 3 days.


Sat Apr 27, 2013 9:49 am
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Joined: Mon Feb 18, 2013 5:11 pm
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Ron Gusack wrote:
Yeah, I think it's easy to get up in chasing numbers and losing track of what makes the engine happy. I spent 3 days on a dyno back in the 80's and walked out of there with less horsepower, but much better numbers. That was probably the best thing I learned from those 3 days.


Just give the engine whatever makes it happy. I've had a number of engine builders tell me you can't run the engine that lean (or that rich) based on what the O2's are reading. So I've simply just re-calibrated the O2's to read what they wanted.... :thumbl:


Mon May 06, 2013 2:32 pm
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