Spark
plugs frequently asked questions
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1.
I know my standard spark plug part number but how can I find a performance
equivalent?
2. My engine has been tuned/modified, do
I need a colder/hotter plug?
3. My vehicle has been modified to run LPG (liquid
propane gas) or dual fuel, do I need to change my spark plugs to
allow for this?
4. Will I get a noticeable power
increase if I replace my standard plugs with Iridium plugs?
5. Which Iridium plugs are better? NGK Iridium
IX or Denso Iridium Power?
6. How long should my spark plugs last?
7. Can you send me a catalogue/patch/promotional
item from NGK/Denso/Champion
8. Why do some spark plugs have multiple
ground electrodes?
9. Do my multi ground electrode
plugs outperform single ground plugs?
10. Can I replace my multi ground plugs
with a single ground Iridium plug?
11. What do the different letters and numbers
mean in my spark plug's part code?
12. Why isn't my vehicle listed in
your application guides? How can I find what plugs my vehicle should
use?
13. What should my spark plug gap be set
to?
14. Should I regap my Iridium spark plugs?
15. How do I regap my spark plugs?
16. What is the correct torque setting for my
engine/spark plugs?
17.
Are there any other factors which may affect
which heat range plug I use?
18.
Can you tell me which
NGK, Champion and Denso plugs are suitable for my car?
19. Can you supply
a resistorless equivalent part for use with Nitrous Oxide?
20. What
sparkplugs do I need for a Mazda RX7?
21. What is the
difference between the ISO and JIS standards? (BCPR and BKR or IK
and IQ etc)
22. Why haven't
you answered my enquiry?
23. Can you cross reference Lodge CB3, Champion 9COML, 7COML etc
24. Do you have a shop? Can I collect from you in person?
25. Is there a plug especially designed for use with LPG (liquid propane gas)?
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| Q1.
I know my standard spark plug part number but how can I find a performance
equivalent? |
| A1. Use our partsearch facility. Type in your original
part number and click 'search'. Your part should be displayed along
with a 'X-ref' button (if this doesn't appear then there are no equivalent
plugs listed in our database). Click the 'X-ref' button, read and
accept our disclaimer and spark plugs with the same dimensions but
different constructions (e.g. copper, platinum, iridium) will be displayed.
You can click the shopping cart icon to add to your order. |
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| Q2.
My engine has been tuned/modified, do I need a colder/hotter plug? |
| A2. You should consult your engine tuner who should
be able to advise you on the correct heat range to get the best from
your engine. As a general rule, an engine may benefit from a colder
grade of plug where modifications made have increased the temperature
in the combustion chamber (increased turbo boost, nitrous oxide use,
increased compression), colder plug will conduct heat away from the
firing tip more quickly and thus help reduce detonation/plug damage. |
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| Q3. My
vehicle has been modified to run LPG (liquid propane gas) or dual
fuel, do I need to change my spark plugs to allow for this? |
| A3. Generally speaking no. Plugs may not last quite
as long as with a standard petrol engine and the ignition system may
have a harder time generating a spark. The denser charge in the combustion
chamber means a higher voltage is required to jump the gap. For this
reason it may help to reduce the spark plug gap by 0.2mm. If spark
plugs become prone to overheating then it may be necessary to replace
with plugs one grade colder. Also, see Q.25. |
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| Q4.
Will I get a noticeable power increase if I replace my standard plugs
with Iridium plugs? |
| A4. Increases are dependant on current plugs, number
of cylinders, cylinder capacity and a host of other details. The biggest
increases seem to be from large engined vehicles with a large number
of cylinders (eg 3.0L V6 and above). Having said that, any improvement
on a small engined vehicle will be more noticeable. Please refer to
our Iridium spark plugs page
for further information. If you are currently using very old/worn
or incorrect spark plugs then replacing with a new set will almost
always produce a noticeable increase in performance. |
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| Q5.
Which Iridium plugs are better? NGK Iridium IX or Denso Iridium Power? |
| A5. That really depends on what you want from your
plugs. Denso's Iridium Power reputedly offer the best performance
but have a shorter service life than NGK's Iridium IX. Please consult
our about Iridium spark plugs
page for a more detailed comparison. |
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| Q6.
How long should my spark plugs last? |
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A6. That is dependant on the application and condition of the engine.
High revving engines, driven hard, (eg motorcycles) will wear plugs
much more quickly than a large engined car which is used for cruising.
Standard copper plugs usually have an estimated service life of
10,000 to 20,000 miles depending upon design and application, Denso
recommend changing their Iridium Power plugs before the maximum
30,000 miles, NGK's Iridium IX may last up to 60,000 miles in a
standard use car engine. Double platinum types may last 60,000 miles
or more and some NGK and Denso OEM Iridium types may last up to
120,000 miles. The plugs optimum performance level is passed a long
time before these intervals so we would recommend changing plugs
regularly as a matter of course. An engine, ignition or carburation/injection
fault or poor adjustment may cause premature wear and/or failure.
Tuned engines, engines driven hard, poor quality fuel amongst other
factors can all dramatically reduce service life.
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| Q7.
Can you send me a catalogue/patch/promotional item from NGK/Denso/Champion |
| A7. Generally speaking, no. We only carry catalogues
for our own reference and we do not stock promotional items as a rule.
Please feel free to request stickers when placing an order,
if any are currently available then we will be happy to help. Otherwise,
you are best advised to contact NGK/Denso/Champion yourself. We are
not at liberty to disclose any contact details for these companies. |
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| Q8.
Why do some spark plugs have multiple ground electrodes? |
| A8. This is an attempt by the manufacturers to
increase the service life of the spark plug. The ground electrodes
can wear down rapidly in some engines. Tiny particles of metal are
removed from the ground electrode each time the plug fires hence they
gradually wear away. There is a misconception that a multi ground
plug will produce mutiple sparks - this is not true, only the nearest
electrode to the centre (i.e. currenty the longest) will spark, as
that becomes worn, another electrode will become the longest and replace
it as the sparking electrode. |
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| Q9.
Do my multi ground electrode plugs outperform single ground plugs? |
| A9. In most cases, no. The additional electrodes
disturb the flow of gases around the spark plug tip and performance
may even be reduced. In addition, for high performance applications
the additional metal within the combustion chamber will retain more
heat and may be more prone to detonation/pre ignition. |
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| Q10.
Can I replace my multi ground plugs with a single ground Iridium plug? |
| A10. Yes, in most cases - providing a suitably
dimensioned Iridium replacement is available. |
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| Q11.
What do the different letters and numbers mean in my spark plugs part
number? |
| A11. Please refer to the manufacturers symbol code
for NGK, Champion or Denso on our technical
home page. |
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| Q12.
Why isn't my vehicle listed in your application guides? How can I
find what plugs my vehicle should use? |
| A12. Our application guides refer only to official
UK imported vehicles, we have very limited access to limited data
for vehicles which were manufactured for use in other countries. We
can often help identify suitable parts for 'grey imports'. We also
have a large list of vehicle specific links on our
links page , many of these websites will have a user group or
forum where you can post your enquiries - there is usually someone
able to tell you what parts you should be using. If all else fails
then a safe bet is to check the currently installed plugs. We can
usually replace these or supply a suitable equivalent. |
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| Q13.
What should my spark plug gap be set to? |
| A13. Most plugs are preset at the factory and shouldn't
need to be adjusted. Please refer to your owners handbook/manual for
the correct gap setting. Our part
finder application guides will also display recommended gap settings.
If you do not have the data available then please refer to the point
of sale where you purchased your spark plugs. We will always check
plug gap setting data for our customers. |
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| Q14.
Should I regap my Iridium spark plugs? |
| A14. In most circumstances, no. The nature of Iridium
spark plugs means that they are able to utilise a larger gap setting
while actually requiring less voltage and straining the ignition system
less. If you *have* to regap Iridium spark plugs (e.g if misfire occurs
due to gap being too large) then do so with extreme care. Do not use
a slide type gapping tool or put pressure on the brittle centre electrode
in any way as it may become damaged. |
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| Q15.
How do I regap my spark plugs? |
| A15. To open the gap, carefully use a pair of fine
nosed pliers or a specialist gapping tool (not slide type for Iridium
or other fine wire types) to bend the ground electrode outwards, away
from the centre electrode. Take care not to contact the porcelain
insulator or the centre electrode as they can be easily damaged. Use
a feeler guage to check for the correct gap size - it should be a
light sliding fit. To close the gap, tap the ground electrode gently
on a hard surface and then open the gap to the required setting using
the method described above. |
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| Q16.
What is the correct torque setting for my engine/spark plugs? |
| A16. Please refer to our torque
reference page for details, noting whether you have an aluminium
or iron cylinder head. |
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| Q17.
Are there any other factors which may affect which heat range plug
I should use? |
| A17. Yes, most important are atmospheric conditions/altitude
(high altitude means less oxygen and colder running, warmer plugs
needed - low altitude is vice versa), grade of fuel used (lower RON
(research octane number) means colder plugs are necessary to prevent
detonation/pre ignition. USA has low RON fuel, Japan has high RON
and UK is in between), driving style is also important - USA has slow
roads and low speed limits meaning hotter plugs are needed, Germany
has the fastest roads and sometimes no speed limit meaning cold plugs
are needed, UK is in between USA and Germany. |
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| Q18.
Can you tell me which NGK, Champion and Denso plugs are suitable for
my car? |
| A18. Please use the application lookup guides on
our homepage to obtain recommended NGK part information, if you need
Denso and Champion equivalents please use the manufacturer cross reference
tables or use our partsearch to locate your NGK part and then continue
to the cross reference information for that part. There are often
many plugs of varying levels of performance so for us to list all
parts available for your vehicle is usually impractical. |
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| Q19.
Can you supply a 'resistorless' equivalent part for use with Nitrous
Oxide? |
| There is usually a resistorless equivalent to standard
resistorised plugs. Our suggestion though, is to upgrade to an Iridium
plug. Since the reasoning behind use of a non resistor plug is the
lower voltage requirement, allowing the plug to fire under extreme
combustion conditions, an Iridium plug will provide this feature as
well as improving firing characteristics. Manufacturers strongly recommend
using only a resistorised plug where specified due to the possibility
of high tension circuit 'electrical noise' interfering with on board
computerised engine management and saftey systems. Please refer to
our nitrous
oxide spark plugs page for further information. |
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| Q20. What
sparkplugs do I need for a Mazda RX7? |
| Most models use a standard plug configuration which
can be found within the application guides on our homepage
. The later twin turbo model uses 2xBUR9EQP and 2xBUR7EQP and it's
vitally important that they are fitted the correct way around. If
you are at all unsure then you should use BUR9EQP in all four chambers
- this should not adversely affect performance. |
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| Q21.
What is the difference between the ISO and JIS
standards? (BCPR and BKR or IK and IQ etc) |
| JIS is the 'Japanese Industrial Standard' and specifies
the height of the spark plug from the gasket or tapered seat of the
sparkplug to the top of the terminal nut (or threaded terminal) as
53mm. ISO is the 'International Standards Organisation' standard for
spark plug height and is 2.5mm shorter than the JIS standard at 50.5mm.
While the small difference in height will not affect most vehicles
(ISO and JIS types can often be interchanged), some vehicles (particularly
with direct fire ignition or specially fitted plug caps) MUST use
the correct plug standard or a bad contact between plug and cap may
be result. See diagram
Common ISO type plugs are NGK BKR, Denso K or IK and Champion C or
RC. Common JIS types are NGK BCP, Denso Q or IQ. |
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| Q22.
Why haven't you answered my enquiry? |
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Whilst we always try to answer genuine enquiries in a timely fashion,
there are instances where this may no be the case.
Email is not 100% reliable, there is no guarantee that we have received
your email just because you have sent it, please try sending again
if you do not receive a reply within 48 hours.
You may have supplied an incorrect email address (common!), check
the settings in your email program - particularly the 'reply address'
field.
There may be a problem with our/your mail delivery service.
We may have considered you were asking us for information for your
own commercial gain or be in competition with us in some way.
Some requests for quotation from certain nations are ignored as
they are invariably attempted fraud.
Were you polite in your request for assistance? We are under no
obligation to provide any help or assistance but under most circumstances
are happy to do so.
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| Q23. Can you cross reference Lodge CB3, Champion 9COML, 7COML ? |
| These are long reach 18mm plugs, unfortunately there are currently no long reach 18mm plugs in production (as far as we are aware). In some instances a shorter reach plug such as Champion D16 may suffice. Your best option is to try and find 'new old stock' from a vintage parts supplier. |
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| Q24. Do you have a shop? Can I collect from you in person? |
| In short, No. This is a mail order business which is why our prices are so low, we have low overheads because we do not have a traditional shop. We do not make any provision for callers in person. If you need to buy from a traditional shop then please do so. |
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| Q25. Is there a plug especially designed for use with LPG (Liquid Propane Gas)? |
| Yes, NGK have recently (mid 2007) released 2 plugs which are designed to work more efficiently and last longer for LPG applications. The plugs feature a platinum chip in the ground electrode and a fine wire Iridium centre electrode. The thread and other metal parts are plated differently to reduce the possibility of a negative reaction to LPG. Part numbers are BKR6EIX-LPG and BPR6EIX-LPG, these will cover a large percentage of the UK car market. |