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06-09-2012, 04:58 AM #1
hussain-vtecHonda-Tech MemberGarage is empty, add now
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***The Basics of Reading a Spark Plug***
HI There H-T Members,
Need to share a sparks plugs tips that i read & gathered
details about it.
So talking About The Basics of Reading a Spark Plug.
Tuning an Engine by the Spark Plug.by BrianOdom.
When tuning a performance engine the spark plug is a important
tuning tool. Being that there are many different tuningtechniques,
I will keep this article about the basics of spark plug reading on
a Quarter-Mile Drag Strip (or wide-open-throttletuning).When tuning
by the spark plug, you must always use a NEW plug to get an
accurate reading. To get a clean plug reading the engine should be
shut down after the run and towed back to the pits. Any running of
the engine after that will skew the plug reading.When tuning by the
spark plug, you must always remember there are two major variables
at play (air fuel ratio and ignitiontiming). To make it easier to
determine your on the right track when tuning, make small
incremental changes and only 1 or 2 changesat a time. Engine tuning
is a learned skill or art, with many different outcomes of getting
a good plug reading. These tips are to identifying a safe engine
tune, horsepower or torque numbers may not be peak. For example, if
I was looking a spark plug showing to much heat. I could pull some
timing out or add more fuel, both changeswould result in less heat.
As I have already stated, air fuel ratios and ignition timing play
a hugepart in the outcome of a good engine tune.The following tips
are just a base line of what to inspect on the spark plug. When
reading a spark plug there are four differentplaces to look. The
first place I inspect is the plug strap, this isthe ignition
timing. The strap will show a color change in two spots on the 90
degree bend. The first mark shows the base timing and the
secondindicates total timing. IF THE SECOND MARK IS SHOWING AT THE
BASE WHERE THE STRAP IS WELDED ON, THIS IS A SIGN OF TOO MUCH
HEAT.An ideal Safe Timing range is when the total timing
discoloring is located just passed the bend.
CURRENT TOP USERSCURRENT TOP USERS
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Next Ill inspect the threaded area for the heat range. The
threads will show dull burnt looking color change, 2-3 threads
isideal. To increase the number of burnt threads, increase the heat
range of the plug.
If you have 4-5-6 threads burnt you need to get a colder
plug.
Inspecting for Air/Fuel can be found in two spots, one spot
known as the Fuel Ring.
On the Fuel Ring, your look for a complete Full Turn of
discoloring. Ideally this should be lightly colored soot.
As the Fuel Ring colored soot darkens, this indicates a richer
Air/Fuel ratio. If your tuning the engine for maximum
horsepower,the ring should be very light and not make a full circle
around the ring.
BUT,BEWARE THIS IS ON THE EDGE OF BEING TOO LEAN.
The second place to inspect for the air/fuel ratio is the the
porcelain.
Excessive fuel leaves light to dark color rings on the
porcelain. Ideal conditions show the porcelain as new to shinny
white. But, beware of a grayish specials as it is most-likely
piston material.
Example#
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Lets analyze this plug, sorry the numbered points aren't clear
but it's 1-4 you can figure it out.
#1 Is a timing indicator, you'll see a definite color change on
the ground strap, see it right about at the arrow. Too much
timingand the color change will be very close to the threaded body
of the plug, too little and it'll be closer to the tip. Ideally we
wantit right in the apex or center of the 90 bend on the ground
strap, in this image timing is perfect.
#4 Arrow shows another indicator of timing, you'll usually see a
brown ring right at the tip of the porcelain area it should be
asharp and defined ring about .020 wide. Wider indicates not enough
timing and any smaller , or only 1/2 way around ornonexistent as in
this image is the second indication of Good timing in the
motor.
#2 The tip of the ground strap, Base timing is Done perfect
.
#3 The threaded portion of the plug gives you the heat range,
look at the threads you'll see that a few toward the tip are adull
burnt looking color the rest are black and shiny. You want about 2
threads showing the heat on the end of the plug andthe rest of the
threads to be shiny, If you using a longer reach plug than this one
2.5 to 3 threads is optimum.To increase the number of burnt threads
increase the heat range of the plug, if you have 4-5-6 threads
burnt you need to geta colder plug.
The Air/Fuel Map
Look at the porcelain and divide it into 3 areas, top, middle
and bottom in about 1/3rds.
Top Area: This area is your idle circuit and for the racer real
has very little meaning. However if your car is a street
drivenvehicle then we need to attempt to get this portion to a dark
gray/tan color by tuning the AFR with the Air Bleeds and the
fourcorner Idle adjustments until we get a clean crisp idle and
total combustion of the fuel at idle. Keep in mind that the
idlecircuits are totally isolated from the rest of the carburetor
and can be tuned with very minimal affect on the WOT position
A/FRatio.
Center Area: This is the area that will show the combustion
chamber condition at part throttle or cruise with the power
valveand secondary venturi's closed. Usually about 30-50 MPH
depending on the gear and weight of the car.
Bottom Area: This is where the racer needs to concentrate all
his efforts, using a 5x or 10x scope you need to look right downto
the bottom of the porcelain where it meets the metal housing of the
plug. This is the area that will leave the color that youneed to
study and tune to. The other 2/3rds of the porcelain will be burned
clean by the high heat generated by WOT and highRPM, this is not
the time to read for cruise or Idle characteristics.
We're looking for a colored ring right at the base of that
porcelain which I refer to as a Fuel Ring. The color will vary
dependingon the type of fuel your burning, Unleaded Pump gas will
leave very little color because of all the additives such as
injectorcleaners and methanol. Most of us run a 108 or 110 in our
bracket cars and these fuels will leave a tan color while the C17
andhigher octane fuels will leave an almost gray fuel ring. If you
study the ring you will see that it starts to show color just
belowthe base of the ground strap, this is caused by the shielding
affect of the strap leaving that portion cooler thus showing
themost color. The ring will develop from each side and form a full
circle of correct color as you get closer and closer to the
correcttune up. If you look down into the bottom of the porcelain
and you detect a thin oily deposit you are seeing oil from
thecombustion chamber caused by either worn or improperly seated
rings, you may also detect this with a new engine that hasn'tfully
seated the rings yet, just don't confuse this with the "Fuel
Ring".
Plug Characteristics
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Shiny or Glazed Porcelain: This occurs for two reasons,
excessive idling or rich idle condition leaving heavy soot
deposits.These deposits will burn and create excessive porcelain
temps causing the glass to melt usually resulting in a down
trackpopping through the exhaust..
You will usually see splotchy deposits on the plugs after the
run, either green or yellow in color and of course the tell tale
shinyglaze.
This glazing of the porcelain actually becomes a conductor and
the spark will jump from the electrode to the porcelain resultingis
a very weak small if any spark.
The porcelain should always have a chalky or dull finish.
Base of threads sooty: This is usually a indication of the plug
not being tight enough allowing it allow air to pulled in to
thechamber and fuel being pushed out, change the plug, tighten to
spec. This area should have a nice dark to medium gray color
without heavy deposits.
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Black or brown specs: This is an indication of detonation
usually caused by too hot of a plug, drop one or two heat ranges
andit should go away. The plug gets so hot that it will start to
detonate the fuel before the ignition fires, this cause a double
flame front and reducesthe efficiency of the combustion process as
these two flame fronts battle each other in the combustion chamber.
The black spots are the result of the fuel deposits being burned
onto the porcelain by the double flame front.
Once you cool down the plug and remove the secondary ignition
source you can re-set your timing to produce the correctcombustion
chamber temp for optimum power.
I've heard 100's of so called tuners and engine builders tell
people that this is normal and nothing to worry about......WRONG.Do
not underestimate the damage that this condition can do to your
engine, drop the plug heat range.
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Shiny little diamond like deposits: It's too late you've already
started to blow the pistons out of it. Start over from
scratch,fatten the carb, back-up the timing and cool down the
plugs. Now start a proper tuning procedure and hopefully you caught
itbefore too much damage was done.
No color mark on ground strap: If your showing good color on the
porcelain but the ground strap fails to show an indicatorthen your
plug is too cold, go up 1 heat range.
If the ground strap is showing a good color line but the
porcelain is showing no color at the base then your plug may be
toohot, drop down a range.I will use maybe 3 different ranges on
one bank, make a pass and from those three different plugs
determine which one iscorrect for the engine.
Added Spark plug FAQ for maximum Knowledge Spark plugA spark
plug (sometimes in British English a sparking plug, colloquially a
plug) is a device for delivering electric current from anignition
system to the combustion chamber of a spark-ignition engine to
ignite the compressed fuel/air mixture by an electricspark, while
containing combustion pressure within the engine. A spark plug has
a metal threaded shell, electrically isolated from a central
electrode by a porcelain insulator. The central electrode, which
may contain a resistor, is connected by a heavily insulated wire to
the output terminal of anignition coil or magneto. The spark plug's
metal shell is screwed into the engine's cylinder head and thus
electrically grounded.
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The central electrode protrudes through the porcelain insulator
into the combustion chamber, forming one or more spark gapsbetween
the inner end of the central electrode and usually one or more
protuberances or structures attached to the inner endof the
threaded shell and designated the "side", "earth", or "ground"
electrode.
Spark plugs may also be used for other purposes; in Saab Direct
Ignition when they are not firing, spark plugs are used tomeasure
ionization in the cylinders - this ionic current measurement is
used to replace the ordinary cam phase sensor, knocksensor and
misfire measurement function. Spark plugs may also be used in other
applications such as furnaces wherein a combustible fuel/air
mixture must be ignited. In this case, they are sometimes referred
to as flame igniters.
OperationThe plug is connected to the high voltage generated by
an ignition coil or magneto. As the electrons flow from the coil, a
voltage difference develops between the central electrode and side
electrode. No current can flow because the fuel and air in the gap
is an insulator, but as the voltage rises further, it begins to
change thestructure of the gases between the electrodes. Once the
voltage exceeds the dielectric strength of the gases, the gases
become ionized. The ionized gas becomes a conductor and allows
electrons to flow across the gap. Spark plugs usually require
voltage of 12,00025,000 volts or more to 'fire' properly, although
it can go up to 45,000 volts. They supply higher current during the
discharge process resulting in a hotter and longer-duration
spark.As the current of electrons surges across the gap, it raises
the temperature of the spark channel to 60,000 K. The intense heat
in the spark channel causes the ionized gas to expand very quickly,
like a small explosion. This is the "click" heard when observing a
spark, similar to lightning and thunder.The heat and pressure force
the gases to react with each other, and at the end of the spark
event there should be a small ballof fire in the spark gap as the
gases burn on their own. The size of this fireball or kernel
depends on the exact composition of the mixture between the
electrodes and the level ofcombustion chamber turbulence at the
time of the spark. A small kernel will make the engine run as
though the ignition timing was retarded, and a large one as though
the timing wasadvanced.
Components of a typical, four stroke cycle, DOHC piston engine.
(E) Exhaust camshaft, (I) Intake camshaft, (S) Spark plug,
(V)Valves, (P) Piston, (R) Connecting rod, (C) Crankshaft, (W)
Water jacket for coolant flow.
Spark plug constructionA spark plug is composed of a shell,
insulator and the central conductor. It passes through the wall of
the combustion chamber and therefore must also seal the combustion
chamber against highpressures and temperatures without
deteriorating over long periods of time and extended use.
Parts of the plug TerminalThe top of the spark plug contains a
terminal to connect to the ignition system. The exact terminal
construction varies depending on the use of the spark plug. Most
passenger car spark plug wires snap onto the terminal of the plug,
but some wires have spade connectors which arefastened onto the
plug under a nut. Plugs which are used for these applications often
have the end of the terminal serve a double purpose as the nut on a
thinthreaded shaft so that they can be used for either type of
connections.
InsulatorThe main part of the insulator is typically made from
sintered alumina, a very hard ceramic material with high
dielectricstrength, printed with the manufacturer's name and
identifying marks, then glazed to improve resistance to surface
sparktracking. Its major function is to provide mechanical support
and electrical insulation for the central electrode, while also
providing anextended spark path for flashover protection. This
extended portion, particularly in engines with deeply recessed
plugs, helps extend the terminal above the cylinder headso as to
make it more readily accessible.
Ribs
By lengthening the surface between the high voltage terminal and
the grounded metal case of the spark plug, the physicalshape of the
ribs functions to improve the electrical insulation and prevent
electrical energy from leaking along the insulatorsurface from the
terminal to the metal case. The disrupted and longer path makes the
electricity encounter more resistancealong the surface of the spark
plug even in the presence of dirt and moisture. Some spark plugs
are manufactured withoutribs; improvements in the dielectric
strength of the insulator make them less important.
Insulator tipOn modern (post 1930's) spark plugs, the tip of the
insulator protruding into the combustion chamber is the same
sinteredaluminium oxide (alumina) ceramic as the upper portion,
merely unglazed. It is designed to withstand 650 C (1,200 F) and
60,000 volts.The dimensions of the insulator and the metal
conductor core determine the heat range of the plug. Short
insulators areusually "cooler" plugs, while "hotter" plugs are made
with a lengthened path to the metal body, though this also depends
onthe thermally conductive metal core.Older spark plugs,
particularly in aircraft, used an insulator made of stacked layers
of mica, compressed by tension in thecentre electrode.With the
development of leaded petrol in the 1930s, lead deposits on the
mica became a problem and reduced the intervalbetween needing to
clean the spark plug. Sintered alumina was developed by Siemens in
Germany to counteract this. Sintered alumina is a superior material
to mica orporcelain because it is a relatively good thermal
conductor for a ceramic, it maintains good mechanical strength and
(thermal)shock resistance at higher temperatures, and this ability
to run hot allows it to be run at "self cleaning" temperatures
withoutrapid degradation. It also allows a simple single piece
construction at low cost but high mechanical reliability.
SealsBecause the spark plug also seals the combustion chamber or
the engine when installed, seals are required to ensure there isno
leakage from the combustion chamber. The internal seals of modern
plugs are made of compressed glass/metal powder, but old style
seals were typically made bythe use of a multi-layer braze. The
external seal is usually a crush washer, but some manufacturers use
the cheaper method of a taper interface and simplecompression to
attempt sealing.
Metal caseThe metal case (or the "jacket" as many people call
it) of the spark plug withstands the torque of tightening the plug,
servesto remove heat from the insulator and pass it on to the
cylinder head, and acts as the ground for the sparks passing
throughthe central electrode to the side electrode.
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Spark plug threads are cold rolled to prevent thermal cycle
fatigue. Also, a marine spark plug's shell is double-dipped,
zinc-chromate coated metal.
Central electrodeThe central electrode is connected to the
terminal through an internal wire and commonly a ceramic series
resistance to reduceemission of RF noise from the sparking. The tip
can be made of a combination of copper, nickel-iron, chromium, or
noble metals. In the late seventies, the developmentof engines
reached a stage where the heat range of conventional spark plugs
with solid nickel alloy centre electrodes wasunable to cope with
their demands. A plug that was cold enough to cope with the demands
of high speed driving would not be able to burn off the
carbondeposits caused by stop-start urban conditions, and would
foul in these conditions, making the engine misfire. Similarly, a
plugthat was hot enough to run smoothly in town, could melt when
called upon to cope with extended high speed running onmotorways.
The answer to this problem, devised by the spark plug
manufacturers, was a centre electrode that carried theheat of
combustion away from the tip more effectively than was possible
with a solid nickel alloy. Copper was the material chosen for the
task and a method for manufacturing the copper-cored centre
electrode was createdby Floform.The central electrode is usually
the one designed to eject the electrons (the cathode) because it is
the hottest (normally) partof the plug; it is easier to emit
electrons from a hot surface, because of the same physical laws
that increase emissions ofvapor from hot surfaces (see thermionic
emission). In addition, electrons are emitted where the electrical
field strength is greatest; this is from wherever the radius of
curvatureof the surface is smallest, from a sharp point or edge
rather than a flat surface (see corona discharge). It would be
easiest to pull electrons from a pointed electrode but a pointed
electrode would erode after only a few seconds. Instead, the
electrons emit from the sharp edges of the end of the electrode; as
these edges erode, the spark becomesweaker and less reliable.
At one time it was common to remove the spark plugs, clean
deposits off the ends either manually or with
specializedsandblasting equipment and file the end of the electrode
to restore the sharp edges, but this practice has become
lessfrequent for two reasons:
1.cleaning with tools such as a wire brush leaves traces of
metal on the insulator which can provide a weak conduction pathand
thus weaken the spark (increasing emissions)
2. plugs are so cheap relative to labor cost, economics dictate
replacement, particularly with modern long-life plugs.
The development of noble metal high temperature electrodes
(using metals such as yttrium, iridium, tungsten, or palladium,
aswell as the relatively high value platinum, silver or gold)
allows the use of a smaller center wire, which has sharper edges
butwill not melt or corrode away. These materials are used because
of their high melting points and durability, not because of their
electrical conductivity (whichis irrelevant in series with the plug
resistor or wires). The smaller electrode also absorbs less heat
from the spark and initial flame energy. At one point, Firestone
marketed plugs with polonium in the tip, under the (questionable)
theory that the radioactivity wouldionize the air in the gap,
easing spark formation.
Side (ground, earth) electrodeThe side electrode is made from
high nickel steel and is welded or hot forged to the side of the
metal shell. The side electrode also runs very hot, especially on
projected nose plugs. Some designs have provided a copper core to
thiselectrode, so as to increase heat conduction. Multiple side
electrodes may also be used, so that they don't overlap the central
electrode.
Spark plug gapSpark plugs are typically designed to have a spark
gap which can be adjusted by the technician installing the spark
plug, bybending the ground electrode slightly. The same plug may be
specified for several different engines, requiring a different gap
for each. Spark plugs in automobiles generally have a gap between
0.035"0.070" (0.91.8 mm). The gap may require adjustment from the
out-of-the-box gap.
A spark plug gap gauge is a disc with a sloping edge, or with
round wires of precise diameters, and is used to measure thegap.
Use of a feeler gauge with flat blades instead of round wires, as
is used on distributor points or valve lash, will give
erroneousresults, due to the shape of spark plug electrodes.The
simplest gauges are a collection of keys of various thicknesses
which match the desired gaps and the gap is adjusted untilthe key
fits snugly. With current engine technology, universally
incorporating solid state ignition systems and computerized fuel
injection, the gapsused are much larger than in the era of
carburetors and breaker point distributors, to the extent that
spark plug gauges fromthat era are much too small for measuring the
gaps of current cars.
The gap adjustment can be crucial to proper engine operation. A
narrow gap may give too small and weak a spark to effectively
ignite the fuel-air mixture, but the plug will almost always fireon
each cycle. A gap that is too wide might prevent a spark from
firing at all or may missfire at high speeds, but will usually have
a spark thatis strong for a clean burn. A spark which
intermittently fails to ignite the fuel-air mixture may not be
noticeable directly, but willshow up as a reduction in the engine's
power and fuel efficiency.
As a plug ages, and the metal of both the tip and hook erode,
the gap will tend to widen; therefore experienced mechanicsoften
set the gap on new plugs at the engine manufacturer's minimum
recommended gap, rather than in the middle of the
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specified acceptable range, to ensure longer life between plug
changes. On the other hand, since a larger gap gives a "hotter" or
"fatter" spark and more reliable ignition of the fuel-air mixture,
andsince a new plug with sharp edges on the central electrode will
spark more reliably than an older, eroded plug,
experiencedmechanics also realize that the maximum gap specified by
the engine manufacturer is the largest which will spark reliably
evenwith old plugs and will in fact be a bit narrower than
necessary to ensure sparking with new plugs; therefore, it is
possible toset the plugs to an extremely wide gap for more reliable
ignition in high performance applications, at the cost of having
toreplace or re-gap the plugs more frequently, as soon as the tip
begins to erode.
Variations on the basic designOver the years variations on the
basic spark plug design have attempted to provide either better
ignition, longer life, or both. Such variations include the use of
two, three, or four equally spaced ground electrodes surrounding
the central electrode. Other variations include using a recessed
central electrode surrounded by the spark plug thread, which
effectively becomesthe ground electrode (see "surface-discharge
spark plug"). Also there is the use of a V-shaped notch in the tip
of the ground electrode. Multiple ground electrodes generally
providelonger life, as when the spark gap widens due to electric
discharge wear, the spark moves to another closer ground
electrode.The disadvantage of multiple ground electrodes is that a
shielding effect can occur in the engine combustion chamber
inhibitingthe flame face as the fuel air mixture burns. This can
result in a less efficient burn and increased fuel consumption.
Surface-discharge spark plug
A piston engine has a part of the combustion chamber that is
always out of reach of the piston; and this zone is where
theconventional spark plug is located. A Wankel engine has a
permanently varying combustion area; and the spark plug is
inevitably swept by the tip seals. Clearly,if a spark plug were to
protrude into the Wankel's combustion chamber it would foul the
rotating tip; and if the plug wererecessed to avoid this, the
sunken spark might lead to poor combustion. So a new type of
"surface discharge" plug was developed for the Wankel. Such a plug
presents an almost flat face to thecombustion chamber. A stubby
centre electrode projects only very slightly; and the entire
earthed body of the plug acts as the side electrode. The advantage
is that the plug sits just beneath the tip-seal that sweeps over
it, keeping the spark accessible to the fuel/airmixture. The "plug
gap" remains constant throughout its life; and the spark path will
continually vary (instead of darting from the centreto the side
electrode as in a conventional plug). Whereas a conventional side
electrode will (admittedly, rarely) come adrift in use and
potentially cause engine damage, this isimpossible with a surface
discharge plug, as there is nothing to break off. Surface-discharge
spark plugs have been produced by inter alia, Denso, Champion and
Bosch.
Sealing to the cylinder headMost spark plugs seal to the
cylinder head with a single-use hollow or folded metal washer which
is crushed slightly betweenthe flat surface of the head and that of
the plug, just above the threads. Some spark plugs have a tapered
seat that uses no washer. The torque for installing these plugs is
supposed to be lower than a washer-sealed plug.
Tip protrusionThe length of the threaded portion of the plug
should be closely matched to the thickness of the head. If a plug
extends too far into the combustion chamber, it may be struck by
the piston, damaging the engine internally. Less dramatically, if
the threads of the plug extend into the combustion chamber, the
sharp edges of the threads act as pointsources of heat which may
cause preignition; in addition, deposits which form between the
exposed threads may make itdifficult to remove the plugs, even
damaging the threads on aluminium heads in the process of removal.
The protrusion of the tip into the chamber also affects plug
performance, however; the more centrally located the spark gap
is,generally the better the ignition of the air-fuel mixture will
be, although experts believe the process is more complex
anddependent on combustion chamber shape. On the other hand, if an
engine is "burning oil", the excess oil leaking into the combustion
chamber tends to foul the plug tipand inhibit the spark; in such
cases, a plug with less protrusion than the engine would normally
call for often collects lessfouling and performs better, for a
longer period. In fact, special "antifouling" adapters are sold
which fit between the plug andthe head to reduce the protrusion of
the plug for just this reason, on older engines with severe oil
burning problems; this willcause the ignition of the fuel-air
mixture to be less effective, but in such cases, this is of lesser
significance.
Heat rangeThe operating temperature of a spark plug is the
actual physical temperature at the tip of the spark plug within the
runningengine. This is important because it determines the
efficiency of plug self-cleaning and is determined by a number of
factors, butprimarily the actual temperature within the combustion
chamber. There is no direct relationship between the actual
operating temperature of the spark plug and spark voltage. However,
the level of torque currently being produced by the engine will
strongly influence spark plug operating temperaturebecause the
maximum temperature and pressure occurs when the engine is
operating near peak torque output (torque andRPM directly determine
the power output). The temperature of the insulator responds to the
thermal conditions it is exposed to in the combustion chamber but
not viceversa. If the tip of the spark plug is too hot it can cause
pre-ignition or sometimes detonation/knocking and damage may occur.
If it is too cold, electrically conductive deposits may form on the
insulator causing a loss of spark energy or the actual shorting-out
of the spark current.
A spark plug is said to be "hot" if it is a better heat
insulator, keeping more heat in the tip of the spark plug. A spark
plug is said to be "cold" if it can conduct more heat out of the
spark plug tip and lower the tip's temperature. Whether a spark
plug is "hot" or "cold" is known as the heat range of the spark
plug. The heat range of a spark plug istypically specified as a
number, with some manufacturers using ascending numbers for hotter
plugs and others doing theopposite, using ascending numbers for
colder plugs.
The heat range of a spark plug is affected by the construction
of the spark plug: the types of materials used, the length
ofinsulator and the surface area of the plug exposed within the
combustion chamber. For normal use, the selection of a spark plug
heat range is a balance between keeping the tip hot enough at idle
to preventfouling and cold enough at maximum power to prevent
pre-ignition or engine knocking. By examining "hotter" and "cooler"
spark plugs of the same manufacturer side by side, the principle
involved can be veryclearly seen; the cooler plugs have a more
substantial ceramic insulator filling the gap between the center
electrode and theshell, effectively allowing more heat to be
carried off by the shell, while the hotter plugs have less ceramic
material, so that thetip is more isolated from the body of the plug
and retains heat better.
Heat from the combustion chamber escapes through the exhaust
gases, the side walls of the cylinder and the spark plug itself.The
heat range of a spark plug has only a minute effect on combustion
chamber and overall engine temperature. A cold plug will not
materially cool down an engine's running temperature. (Too hot of a
plug may, however, indirectly lead to arunaway pre-ignition
condition that can increase engine temperature.) Rather, the main
effect of a "hot" or "cold" plug is to affect the temperature of
the tip of the spark plug.
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25/3/13 ***The Basics of Reading a Spark Plug*** -
Honda-Tech
honda-tech.com/showthread.php?t=3063102 10/19
It was common before the modern era of computerized fuel
injection to specify at least a couple of different heat ranges
forplugs for an automobile engine; a hotter plug for cars which
were mostly driven slowly around the city, and a colder plug
forsustained high speed highway use. This practice has, however,
largely become obsolete now that cars' fuel/air mixtures and
cylinder temperatures are maintainedwithin a narrow range, for
purposes of limiting emissions. Racing engines, however, still
benefit from picking a proper plug heat range. Very old racing
engines will sometimes have twosets of plugs, one just for starting
and another to be installed for driving once the engine is warmed
up.
Spark plug manufacturers use different numbers to denote heat
range of their spark plugs.
Reading spark plugsThe spark plug's firing end will be affected
by the internal environment of the combustion chamber. As the spark
plug can be removed for inspection, the effects of combustion on
the plug can be examined. An examination, or "reading" of the
characteristic markings on the firing end of the spark plug can
indicate conditions withinthe running engine. The spark plug tip
will bear the marks as evidence of what is happening inside the
engine. Usually there is no other way to know what is going on
inside an engine running at peak power. Engine and spark plug
manufacturers will publish information about the characteristic
markings in spark plug reading charts. Such charts are useful for
general use but are of almost no use in reading racing engine spark
plugs, which is an entirelydifferent matter.
A light brownish discoloration of the tip of the block indicates
proper operation; other conditions may indicate malfunction. For
example, a sandblasted look to the tip of the spark plug means
persistent, light detonation is occurring, often unheard. The
damage that is occurring to the tip of the spark plug is also
occurring on the inside of the cylinder. Heavy detonation can cause
outright breakage of the spark plug insulator and internal engine
parts before appearing assandblasted erosion but is easily heard.
As another example, if the plug is too cold, there will be deposits
on the nose of the plug. Conversely if the plug is too hot, the
porcelain will be porous looking, almost like sugar. The material
which seals the central electrode to the insulator will boil out.
Sometimes the end of the plug will appear glazed,as the deposits
have melted.
An idling engine will have a different impact on the spark plugs
than one running at full throttle. Spark plug readings are only
valid for the most recent engine operating conditions and running
the engine under differentconditions may erase or obscure
characteristic marks previously left on the spark plugs. Thus, the
most valuable information is gathered by running the engine at high
speed and full load, immediately cutting theignition off and
stopping without idling or low speed operation and removing the
plugs for reading.
Spark plug reading viewers, which are simply combined
flashlight/magnifiers, are available to improve the reading of the
sparkplugs.
-
25/3/13 ***The Basics of Reading a Spark Plug*** -
Honda-Tech
honda-tech.com/showthread.php?t=3063102 11/19
Indexing spark plugsA matter of some debate is the "indexing" of
plugs upon installation, usually only for high performance or
racing applications;this involves installing them so that the open
area of the spark gap, not shrouded by the ground electrode, faces
the center ofthe combustion chamber, towards the intake valve,
rather than the wall. Some engine tuners who believe that this will
maximize the exposure of the fuel-air mixture to the spark, also
ensuring thatevery combustion chamber is an even in layout and
therefore result in better ignition ; others, however, believe that
this isuseful only to keep the ground electrode out of the way of
the piston in ultra-high-compression engines if clearance
isinsufficient. In any event, this is accomplished by marking the
location of the gap on the outside of the plug, installing it, and
noting thedirection in which the mark faces; then the plug is
removed and additional washers are added so as to change the
orientationof the tightened plug. This must be done individually
for each plug, as the orientation of the gap with respect to the
threads of the shell is random. Some plugs are made with a
non-random orientation of the gap and are usually marked as such by
a suffix to the modelnumber; typically these are specified by
manufacturers of very small engines where the spark plug tip and
electrodes form asignificantly large part of the shape of the
combustion chamber. The Honda Insight has indexed spark plugs from
factory, with four different part numbers available corresponding
to thedifferent degrees of indexing to achieve most efficient
combustion and maximum fuel efficiency.
From wikipedia link
below:http://en.wikipedia.org/wiki/Spark_plug
New Link's
Reading Spark Plugs(This applies to Naturally Aspirated as well
as Nitrous
Engines)http://www.angelfire.com/fl4/pontiac...Readplugs.html
Reading Spark Plugsby Meaux Racing
Headshttp://www.dragstuff.com/techarticle...ead-plugs.html
Spark Plug Reading 101 by Mike
Canterhttp://www.dragstuff.com/techarticle...ark-plugs.html
Blown Alcohol Motor Spark Plug Reading 101 by Mike
Canterhttp://www.dragstuff.com/techarticle...ark-plugs.html
Nitrous Spark Plug Picturesby John Heard and
Friends...http://www.dragstuff.com/techarticle...-pictures.html
So guy's feel free to ADD Tips.
Last edited by hussain-vtec; 07-04-2012 at 05:55 AM. Reason: New
link's added NGK Spark plugs Reading And heat rang.
06-09-2012, 05:01 AM #2
Spawne32Honda-Tech Member
Re: ***The Basics of Reading a Spark Plug***
-
25/3/13 ***The Basics of Reading a Spark Plug*** -
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1995 Acura Integra
Join Date: May 2009Location: New JerseyPosts: 5,023iTrader
Rating: (1)
I love this thread, can this get a
sticky?__________________Spawne's Supercharged B20 Build- 14.6 @
93.5 on 7psi!
Quote:
Originally Posted by mar778c
Ignorance on parade.
06-09-2012, 05:24 AM #3
hussain-vtecHonda-Tech MemberGarage is empty, add now
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Re: ***The Basics of Reading a Spark Plug***
Quote:
Originally Posted by Spawne32 I love this thread, can this get a
sticky?
Thank's for the love.
About Sticky don't No But hope that every one on H-T Read
it.
06-09-2012, 05:33 AM #4
OGlurkerHonda-Tech MemberGarage is empty, add now Join Date: May
2012Posts: 7iTrader Rating: (0)
Re: ***The Basics of Reading a Spark Plug***
06-09-2012, 06:29 AM #5
rich7777Honda-Tech MemberGarage is empty, add now
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Re: ***The Basics of Reading a Spark Plug***
Sweet, thank you for you efforts on both this thread and the
cooling systerm thread.
I agree with Spawn, STICKY !!!!!!!__________________My B16 build
: http://honda-tech.com/showthread.php?t=2997100
06-09-2012, 10:26 AM #6
LocoJoeHonda-Tech MemberGarage is empty, add now
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Re: ***The Basics of Reading a Spark Plug***
Great Contribution!!! Thread very helpful.
06-09-2012, 01:11 PM #7
hussain-vtecHonda-Tech MemberGarage is empty, add now
Re: ***The Basics of Reading a Spark Plug***
Quote:
-
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Originally Posted by OGlurker
Thank's
Quote:
Originally Posted by rich7777
Sweet, thank you for you efforts on both this thread and the
cooling systerm thread.
I agree with Spawn, STICKY !!!!!!!
Any thing you need guy's don't shy just ask.
Quote:
Originally Posted by LocoJoe
Great Contribution!!! Thread very helpful.
I will always share major knowledge.
__________________***High-Performance Cooling
System***http://honda-tech.com/showthread.php?t=3062009***The
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Plug***http://honda-tech.com/showthread.php?t=3063102
ALL-TECHwire
06-09-2012, 01:18 PM #8
lilpat93accordHonda-Tech MemberGarage is empty, add now Join
Date: Oct 2009Posts: 72iTrader Rating: (0)
Re: ***The Basics of Reading a Spark Plug***
Very good and informative read
06-09-2012, 01:30 PM #9
hussain-vtecHonda-Tech MemberGarage is empty, add now
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Re: ***The Basics of Reading a Spark Plug***
Quote:
Originally Posted by lilpat93accord
Very good and informative read
Thanks.
06-11-2012, 05:00 AM #10
hussain-vtecHonda-Tech MemberGarage is empty, add now
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Re: ***The Basics of Reading a Spark Plug***
Bump For experiencing and sharing your own skills.
The best way to read a plug, Magnifying Glasses.heat rang setups
N/A or F/I,..Tips to guide us H-T members to the Top
06-11-2012, 02:01 PM #11
rs250nutHonda-Tech MemberGarage is empty, add now
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Re: ***The Basics of Reading a Spark Plug***
Bad *** thread, thanks for sharing
06-11-2012, 11:34 PM #12
hussain-vtecHonda-Tech MemberGarage is empty, add now
Re: ***The Basics of Reading a Spark Plug***
Quote:
Originally Posted by rs250nut
-
25/3/13 ***The Basics of Reading a Spark Plug*** -
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honda-tech.com/showthread.php?t=3063102 14/19
Join Date: Mar 2009Location: BAHRAINPosts: 275iTrader Rating:
(0)
Bad *** thread, thanks for sharing
Your welcome, Get a New spark plug's set make third gear WOT
before rev limit and engine should be shut down after the runuse a
Magnifying Glass read it and take image shoot to share it with
us.
Pro Spark Plug Viewer link
below:http://www.powerhouseproducts.com/ph...ug-viewer.html
SPARK PLUG LIGHT & MAGNIFIER link
below:http://www.speedwaymotors.com/Spark-...fier,2642.htmlTips:With
practice you will gain enough experience.
Last edited by hussain-vtec; 06-15-2012 at 06:55 AM. Reason: TO
ADD SPARK PLUG MAGNIFIER TOOLS
06-11-2012, 11:41 PM #13
racebumHonda-Tech MemberGarage is empty, add now
Re: ***The Basics of Reading a Spark Plug***
^
jeep cherokee?
-
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Join Date: Aug 2007Location: Detonation KingPosts: 9,514iTrader
Rating: (0)
__________________carpet cleaning beaverton Do you own a turbo
honda and want the build to have it's own page for free?
seeturboinstall.net
06-12-2012, 12:03 AM #14
hussain-vtecHonda-Tech MemberGarage is empty, add now
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Re: ***The Basics of Reading a Spark Plug***
Quote:
Originally Posted by racebum
^
jeep cherokee?
Don no.It's a image URL to clarified my point.
06-12-2012, 04:15 AM #15
DDTECHHonda-Tech Member1992 Honda Civic
Join Date: Aug 2009Location: BatonRouge,LouisianaPosts:
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Re: ***The Basics of Reading a Spark Plug***
Very good write up.__________________DDTECH - Round2Motorsports
- Myers Manifolds - YCU - AFITurbo - Sheepey INC - Phearable.net
Custom Camshafts, VTEC Killers, and Rollers for your Honda
06-12-2012, 04:33 AM #16
hussain-vtecHonda-Tech MemberGarage is empty, add now
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Re: ***The Basics of Reading a Spark Plug***
Quote:
Originally Posted by ALL M0T0R
Very good write up.
Thank's bro.
__________________***High-Performance Cooling
System***http://honda-tech.com/showthread.php?t=3062009***The
Basics of Reading a Spark
Plug***http://honda-tech.com/showthread.php?t=3063102
ALL-TECHwire
06-12-2012, 08:05 AM #17
FreshdotHonda-Tech MemberGarage is empty, add now Join Date: Nov
2006Location: NYCPosts: 1,502iTrader Rating: (0)
Re: ***The Basics of Reading a Spark Plug***
Quote:
Originally Posted by hussain-vtec
Don no.It's a image URL to clarified my point.
awesome thread!
06-12-2012, 08:07 PM #18
yungmulacrxHonda-Tech Member1994 Honda Accord Join Date: Nov
2010Posts: 75iTrader Rating: (0)
Re: ***The Basics of Reading a Spark Plug***
This plug is from a third gear pull to 7500 with wideband
reading 12.9 afr.. I cant really see any afr readings on it.. This
was abrand new plug with one pull on it.. Do i have to do multiple
pulls?? What do you think of it?
Last edited by yungmulacrx; 06-13-2012 at 12:31 PM.
-
25/3/13 ***The Basics of Reading a Spark Plug*** -
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06-13-2012, 12:41 AM #19
hussain-vtecHonda-Tech MemberGarage is empty, add now
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Re: ***The Basics of Reading a Spark Plug***
Quote:
Originally Posted by yungmulacrx This plug is from a third gear
pull to 7500 with wideband reading 12.9 afr.. I cant really see any
afr readings on it.. This wasa brand new plug with one pull on it..
Do i have to do multiple pulls?? What do you think of it?
Thanks Yungmulacrx for your Contribution and testing now we can
start the making of the best Thread ever. (Wow big images Above)
change the size like these.
Things need to be considered & configured:
Engine specs N/A or F/I, Engine Compression, sparks plug set of
6's or 7's or 8's, where it's gapped at between 0.035"0.070"(0.91.8
mm).
AEM Says on the AEM EFI Basics:Engine Specs: Spark plug
gap:Natural aspirated up to 11.0:1 CR 1.1mm (.044'') Natural
aspirated up to 11.0:1 to 14.0: CR 1.8mm (.032'') Forced Induction
to 20-PSI .7mm (.028'') Forced Induction to 40-PSI .6mm
(.022'')
AEM PDF link
below:http://www.aemelectronics.com/files/...asics_V1.3.pdf
Need your Engine Specs along with your spark plugs don't forget
to mention in your new post.
First: It's hard to see it when the plugs are fresh set.Second:
Depending where in the rpm range you shut down, Color change should
take place right at the bend of the groundstrap.I suggest doing the
fallowing steps:Try a couple Engine WOT shut downs somewhere in
between 4000-5500 RPM & another full throttle from run 5000 to
7000RPM and see the Color change of the bend of the ground
strap.
By reading you will learn things but by practicing you well End
up Expert.
__________________***High-Performance Cooling
System***http://honda-tech.com/showthread.php?t=3062009***The
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ALL-TECHwire
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06-13-2012, 03:03 AM #20
hussain-vtecHonda-Tech MemberGarage is empty, add now
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Re: ***The Basics of Reading a Spark Plug***
Quote:
Originally Posted by Freshdot
awesome thread!
Thanks,Your awesome reader To!!
Guy's It has been updated with Spark plug FAQ Above.
Enjoy
06-13-2012, 03:55 AM #21
DDTECHHonda-Tech Member1992 Honda Civic
Join Date: Aug 2009Location: BatonRouge,LouisianaPosts:
6,090iTrader Rating: (0)
Re: ***The Basics of Reading a Spark Plug***
That plug needs some passes on it before you can read
it.__________________DDTECH - Round2Motorsports - Myers Manifolds -
YCU - AFITurbo - Sheepey INC - Phearable.net Custom Camshafts, VTEC
Killers, and Rollers for your Honda
06-13-2012, 06:27 AM #22
yungmulacrxHonda-Tech Member1994 Honda Accord Join Date: Nov
2010Posts: 75iTrader Rating: (0)
Re: ***The Basics of Reading a Spark Plug***
Sorry for the big pics. Engine is a f20b ,11.0 compression,
stock internals, euro r intake manifold, cheap ebay header w/2.5
incollector mod, custom 2.5in exhaust, cold air intake, and tuned
on s300.. Spark plugs are zfr6f-11 gapped at .044. Thanks forthe
advice i will sure try it.. This is something ive been wanting to
learn. Engine was shut down at 7500 wot..
06-13-2012,
07:57 AM
Spawne32Honda-TechMember1995 AcuraIntegra
Join Date: May2009Location: NewJerseyPosts: 5,023iTrader
Rating:(1)
Re: ***The Basics of Reading a Spark Plug***
one of my old plugs with a few passes on it
-
25/3/13 ***The Basics of Reading a Spark Plug*** -
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__________________Spawne's Supercharged B20 Build- 14.6 @ 93.5
on 7psi!
Quote:
Originally Posted by mar778c
Ignorance on parade.
06-13-2012, 08:24 AM #24
Blaze45Honda-Tech MemberGarage is empty, add now
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Re: ***The Basics of Reading a Spark Plug***
This thread = winning.__________________F22a F2D Civic build
http://jwsparetime.blogspot.com Dirt Bike blog
http://extremeist45.tumblr.com
06-14-2012, 04:45 AM #25
hussain-vtecHonda-Tech MemberGarage is empty, add now
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Re: ***The Basics of Reading a Spark Plug***
Quote:
Originally Posted by ALL M0T0R
That plug needs some passes on it before you can read it.
Agree.
Quote:
Originally Posted by yungmulacrx
Sorry for the big pics. Engine is a f20b ,11.0 compression,
stock internals, euro r intake manifold, cheap ebay header w/2.5in
collector mod, custom 2.5in exhaust, cold air intake, and tuned on
s300.. Spark plugs are zfr6f-11 gapped at .044.Thanks for the
advice i will sure try it.. This is something ive been wanting to
learn. Engine was shut down at 7500 wot..
It's OK,Your welcome any time.
As mentioned in heat rang Above in Spark plug FAQ the level of
torque currently being produced by the engine will strongly
-
25/3/13 ***The Basics of Reading a Spark Plug*** -
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0
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influence spark plug operating temperature because the maximum
temperature and pressure occurs when the engine isoperating near
peak torque output (torque and RPM directly determine the power
output).
This is why i mention to Try a couple Engine WOT shut downs
somewhere in between 4000-5500 RPM & another full throttlefrom
run 5000 to 7000 RPM and see the Color change of the bend of the
ground strap.
See where is Peak Torque Output.
Quote:
Originally Posted by Spawne32
one of my old plugs with a few passes on it
Spawne32 thank you for sharing this image,I believe that you
read theEntire thread.
So i would like you to read your spark plug what can you See
from it!
Quote:
Originally Posted by Blaze45
This thread = winning.
Thank you.
Guys I make a new update to the thread New link's.
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