Reading a spark Plug
#1
07-28-2004, 04:20 PM
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Reading a spark Plug
Been trying to figure out if I'm lean or Rich.. puled the plug with my current set up & the ground electrode is white but the insulator is black, what gives? what part of my throttle is rich & wich is lean? Stock for the P-360 is 155 & my manual tells me to use a 145 for me elevation (4500 - 7000) but I have only been using a 150 & am concerned if I'm lean? Only mod I have is a Twin Air filter
#2
07-28-2004, 04:45 PM
Reading a spark Plug
Here is a copy of a post from N2XLR8N...
I've used this particular method for fuel tuning (even without the use of a Wide Band oxygen sensor) on everything from 555 CI Big Block Chevies to my Kawi V-twin. It works, every time. One thing to point out: If you are tuning a new combination for the first time, and you like to be on the "lean is mean" side, or, if you are looking for the presence of detonation, you MUST utilize a magnifier of some sort....
Reading Plugs:
***This applies to Naturally Asparated as well as Nitrous Engines***
This is valid for track only(not street driving) if you shut your engine off at
the finish line, then remove the plugs for reading. Or if you are on the dyno for full load acceleration or steady state dyno tests. It's best to view plugs with a 10x power illuminated magnifying type glass. What each part of a plug signifies:
"Ground Strap" = Heat Range
"Plug's Base Ring" = Jetting
"Porcelain" = signs of preignition/detonation
Heat Range:
The ground strap indicates the heat range of the spark plug. If the "color"
of the ground strap "changes" too close to the ground strap's end, (located
above the center electrode), then the heat range is "too cold", meaning that the strap is losing heat too quickly to the base ring. It is not able to burn off deposits until near its end.
If the "color" of the strap changes near where it is welded/attached to the
base ring (last thread ring), then the plug heat-range is "too hot", because
heat is not being tranferred or cooled from the strap to the base ring
quickly enough. The strap might begin to act like a "glow-plug". Eventually
causing preignition and/or detonation later on. The proper heat range is
when the "color" is at the half-way point on the strap. This means the plug
is neither too cold or too hot.
Color: Meaning the evidence of heat or lack of heat by the appearance (dark vs light) color of metal.
Jetting:
The air/fuel mixture ratio shows up on the base ring. This is the last thread ring, it has the strap welded to it. You want a full turn of light soot color on the base ring!!! If you want to tune for maximum power, then you want 3/4 to 7/8ths of a full turn of light soot color to show up on the base ring. This is on ragged-edge of being too lean, but will make the most HP in most engines. To be safe, leave it at a full turn of light soot color. If the base ring has a full turn of color, but there are "spots" of heavy build-up of "dry soot" on top of color, then jetting is too rich.
****If the base ring has a full turn of color with some spots of heavy dry
soot, then jetting is too rich, regardless if the porcelain is BONE-WHITE", jetting is still TOO RICH.****
The old method of reading the porcelain to be "tan or light brown" went out the window with today's fuels. Bottom line:
* Do not look at the porcelain to read jetting. *
Pre-ignition/Detonation:
The porcelain shows up pre-ignition and detonation (timing/octane). It will
not accurately reveal jetting/air/fuel ratios. To look for the first/beginning
signs of detonation, search the white porcelain for tiny black specks or
shiny specks of aluminum that have fused to the porcelain. When
detonation occurs, part of the air/fuel mixture explodes instead of burning,
the explosion is heard as a "metallic knock", this audible knock is the result of a sound shock-wave, this shock wave travels back and forth across the clearance volume "disrupting" the cooler boundary layer gases that cover the entire clearance volume area. This disruption allows "more" heat to be transferred into parts, especially, domes/piston tops,...along with the very rapid rise in pressure like a hammer blow, pistons can get torched with melted sides and holes !!! With the early signs of detonation, the shock-wave will also rattle rings causing the tiny amounts of oil that now gets by rings, to be fused to the white porcelain as tiny black specks, also fused as specks are soot that was clinging to clearance volume surfaces in the relatively "still-air" of the boundary layer. One step beyond the black specks, will be tiny specks/***** of aluminum coming off the pistons that will be fused to white porcelain,....the next step to be reached is occasional pieces of the porcelain being broken-off as detonation gets worse, etc. Soon after that are holes, blown head gaskets, broken connecting rods, etc. Think ashtray, and you begin to see the picture.
*** Additional signs of beginning detonation are piston rings. By
comparing ring's "free diameter" to "out-of-box" free diameters of new
unused rings will reveal beginning of detonation before much harm is
caused !!! This is a result of the above previous explanation about heat
being transferred more readily because the of the relatively cooler
boundary layer being disrupted by the shock-wave. A piston ring is a simple spring, when a spring is over-heated it will loose tension.
Also on the "Center Electrode", something else to look for. The very tiny
sharply defined porcelain "ditch" that encircles the center electrode, will
also show up early signs of pre-ignition or detonation as the wrong
heat-range. Look for signs of the ditch beginning to fill up with melted
porcelain. You will need a 5x or 10x magnifying glass to check this.
RECOMMENDED SPARK PLUGS FOR HP / NITROUS APPLICATIONS:
From personal experience, I prefer the NGK line of plugs because they are the easiest to read. Also a good plug is the Autolite brand. I do not use any plug utilizing a electrode such as Platinum, Iridium, or Inconel. These metals are very dense, and the idea is to use the electrode as a fuse, not your pistons. Hope this helps!
I've used this particular method for fuel tuning (even without the use of a Wide Band oxygen sensor) on everything from 555 CI Big Block Chevies to my Kawi V-twin. It works, every time. One thing to point out: If you are tuning a new combination for the first time, and you like to be on the "lean is mean" side, or, if you are looking for the presence of detonation, you MUST utilize a magnifier of some sort....
Reading Plugs:
***This applies to Naturally Asparated as well as Nitrous Engines***
This is valid for track only(not street driving) if you shut your engine off at
the finish line, then remove the plugs for reading. Or if you are on the dyno for full load acceleration or steady state dyno tests. It's best to view plugs with a 10x power illuminated magnifying type glass. What each part of a plug signifies:
"Ground Strap" = Heat Range
"Plug's Base Ring" = Jetting
"Porcelain" = signs of preignition/detonation
Heat Range:
The ground strap indicates the heat range of the spark plug. If the "color"
of the ground strap "changes" too close to the ground strap's end, (located
above the center electrode), then the heat range is "too cold", meaning that the strap is losing heat too quickly to the base ring. It is not able to burn off deposits until near its end.
If the "color" of the strap changes near where it is welded/attached to the
base ring (last thread ring), then the plug heat-range is "too hot", because
heat is not being tranferred or cooled from the strap to the base ring
quickly enough. The strap might begin to act like a "glow-plug". Eventually
causing preignition and/or detonation later on. The proper heat range is
when the "color" is at the half-way point on the strap. This means the plug
is neither too cold or too hot.
Color: Meaning the evidence of heat or lack of heat by the appearance (dark vs light) color of metal.
Jetting:
The air/fuel mixture ratio shows up on the base ring. This is the last thread ring, it has the strap welded to it. You want a full turn of light soot color on the base ring!!! If you want to tune for maximum power, then you want 3/4 to 7/8ths of a full turn of light soot color to show up on the base ring. This is on ragged-edge of being too lean, but will make the most HP in most engines. To be safe, leave it at a full turn of light soot color. If the base ring has a full turn of color, but there are "spots" of heavy build-up of "dry soot" on top of color, then jetting is too rich.
****If the base ring has a full turn of color with some spots of heavy dry
soot, then jetting is too rich, regardless if the porcelain is BONE-WHITE", jetting is still TOO RICH.****
The old method of reading the porcelain to be "tan or light brown" went out the window with today's fuels. Bottom line:
* Do not look at the porcelain to read jetting. *
Pre-ignition/Detonation:
The porcelain shows up pre-ignition and detonation (timing/octane). It will
not accurately reveal jetting/air/fuel ratios. To look for the first/beginning
signs of detonation, search the white porcelain for tiny black specks or
shiny specks of aluminum that have fused to the porcelain. When
detonation occurs, part of the air/fuel mixture explodes instead of burning,
the explosion is heard as a "metallic knock", this audible knock is the result of a sound shock-wave, this shock wave travels back and forth across the clearance volume "disrupting" the cooler boundary layer gases that cover the entire clearance volume area. This disruption allows "more" heat to be transferred into parts, especially, domes/piston tops,...along with the very rapid rise in pressure like a hammer blow, pistons can get torched with melted sides and holes !!! With the early signs of detonation, the shock-wave will also rattle rings causing the tiny amounts of oil that now gets by rings, to be fused to the white porcelain as tiny black specks, also fused as specks are soot that was clinging to clearance volume surfaces in the relatively "still-air" of the boundary layer. One step beyond the black specks, will be tiny specks/***** of aluminum coming off the pistons that will be fused to white porcelain,....the next step to be reached is occasional pieces of the porcelain being broken-off as detonation gets worse, etc. Soon after that are holes, blown head gaskets, broken connecting rods, etc. Think ashtray, and you begin to see the picture.
*** Additional signs of beginning detonation are piston rings. By
comparing ring's "free diameter" to "out-of-box" free diameters of new
unused rings will reveal beginning of detonation before much harm is
caused !!! This is a result of the above previous explanation about heat
being transferred more readily because the of the relatively cooler
boundary layer being disrupted by the shock-wave. A piston ring is a simple spring, when a spring is over-heated it will loose tension.
Also on the "Center Electrode", something else to look for. The very tiny
sharply defined porcelain "ditch" that encircles the center electrode, will
also show up early signs of pre-ignition or detonation as the wrong
heat-range. Look for signs of the ditch beginning to fill up with melted
porcelain. You will need a 5x or 10x magnifying glass to check this.
RECOMMENDED SPARK PLUGS FOR HP / NITROUS APPLICATIONS:
From personal experience, I prefer the NGK line of plugs because they are the easiest to read. Also a good plug is the Autolite brand. I do not use any plug utilizing a electrode such as Platinum, Iridium, or Inconel. These metals are very dense, and the idea is to use the electrode as a fuse, not your pistons. Hope this helps!
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