Spark Plug Gap

[MT94]

Hi there i am looking to changing my spark plugs but i have no idea what gap the spark plugs have to be set at if i look up spark plugs using my reg number it brings back all different plugs with different gaps for example a Bosch spark plug with 4 electrodes shows a gap of 1.6mm where as the same plug with 1 electrode has a gap of 0.7mm i feel this is a big difference and just wondered if anyone had a definite answer.
Cheers.
Matt.

 

[MACK]

I'd go with whatever the actual plug manufacturer recommends for their plug for the car. Differences with gap with differing electrodes is common so I wouldn't worry too much on that front. Plugs are usually correctly capped from the factory these days so it's more of a case of checking it if you want rather than actually needing to set them.

 

[ph001]

Don't bother with multi-electrode plugs. Go with a single electrode iridium such as this http://www.opieoils.co.uk/pv-214128-bosch-iridium-spark-plug-0242240653-single.aspx

 

[MT94]

Hi thanks for the replies i have never changed or bought spark plugs before so i am clueless thanks for the link to the plugs they do say they are for fuel type CNG/LPG will these still work in my car or do i need a different type as i have heard iridium plugs are the ones to buy pre gapped.
sorry again completely lost in all of this as i said.

Cheers.
Matt.

 

[ph001]

They are not just for CNG/LPG but if used in these cars they have to be replaced every 30,000km. Many people think that multi-electrode plugs result in 2 (or 4) sparks simultaneously but this is not typically how they work - you still tend to get one spark, it just jumps to whichever electrode is nearest and then as that electrode wears it goes to the next nearest etc etc.

The idea is longer plug lifetime but some research has shown that you actually get a 'diluted' spark as some ignition energy is lost in the ionisation of the air in the other gaps even though you don't actually get breakdown and the resulting spark.

Materials like iridium are far far better, will outlast a multi-electrode plug and you get one strong condensed spark. Perfect.

 

[patriot66]

Don't bother with expensive 'unobtanium' electrode plugs, they just last a bit longer. They won't give you anymore power. Fit quality regular Bosch plugs every 2 years.

 

[ph001]

Don't bother with expensive 'unobtanium' electrode plugs, they just last a bit longer. They won't give you anymore power. Fit quality regular Bosch plugs every 2 years.

Why? Iridium lasts 2-3x as long but doesn't cost 2-3 times more. Factor in the time and hassle to change (admittedly not much) and it doesn't make sense not to fit them.

 

[MT94]

Thanks for your replies learn something new everytime i post on here slowly building my mechanical knowledge
Cheers.
Matt.

 

[csquire4]

Lots of people have gone for this offer:

http://www.halfords.com/motoring/car-parts/ignition/spark-plugs/ngk-29-spark-plug-x4-bkr6equp#

 

[DaveZ4richardson]

Am looking to replace mine too. 37% discount at Eurocarparts.

 

[ph001]

Thats still a lot more than the Opie Oils price, even with the discount.

 

[DaveZ4richardson]

Not sure why i chose 7 either lol :roll:

 

[ph001]

..always good to have a spare!

 

[groovy_hippy]

I paid £57.74 for 6x NGK iridium ones from CarParts4Less. Any thoughts on what the gap should be?

 

[ph001]

Iridium should be pre-gapped - they are not supposed to be adjusted. I think 0.7mm is correct from memory.