Will These Spark Plugs Be Ok On My 8v

[Rally Slag 0]

bought a set of plugs ages ago for my 205 project but the engine went bang, they are just sitting in my cupboard at the mo in the box doing FA. The plugs are NGK R7436-9 Iridieum ones. Would it be ok to use these in my 1.9 309 8V with a 4 branch manifold, group n exhaust, induction kit, 8mm leads and allways run on 99ron fuel? a friend of mine who races an ax reckons the compression isnt high enough for them plugs and i should run a 7 or at the highest an 8.

 

What do you guys rekon, would the plugs be no good, and cost me to loose power or would they be fine to use? I personaly think they would be ok, but just wanted some other peoples opinions.

 

I asume the number my friend means is the last number, the 9 which i beleive is the resistance of plug, but correct me if im wrong, but you cant get a R7436-7 but they do make a R7436-8. Only thing is a bought these plugs ages ago for something else but never got round to it and they were very expensive, but could probably change them if i had to as i got them at trade, but may have to ave a bit of a fight about it lol, anyway,

 

cheers

Edited August 29, 2006 by Rally Slag

[boombang 2]

that last number is usually temperature rating!

 

check on the NGK website.

[Rally Slag 0]

yeah just checked the NGK website, they do an 8, 9 or 10. my friend said they may be to high a heat raiting (think it was something like that) but didnt quite under stand him, if someone else could explain a bit better as to why and what it would do to the engine that would help, i read a little bit on the NGK site but im tired and it was a long page but i thought the 9 being in the middle of the 3 heat ranges would still be ok to use

Edited August 29, 2006 by Rally Slag

[Rally Slag 0]

anyone?

[bales 1]

The temperature rating of the plug refers to how hot it runs in the engine. The cooling of the plug is by heat dissipitation through the body of the plug and it being exposed to the air/fuel mixture. But the main heat factor is the spark plug body and how well it dissipitates the heat.

 

The spark plug needs to be hot enough to burn off the carbon deposits that form but not too hot that it causes detonation or damages the electrode.

 

In terms of whether it will work in your engine I dont know but their website should be able to help you. In terms of the worse thing that could happen, if it is too hot it will ignite the mixture too soon and cause detonation and knacker your entire engine, or if its too cold the carbon wont burn off and it will foul up and your engine will miss constantly and be difficult to start.

 

Assuming your engine is running okay and the mixture is correct the colour of the spark plug will tell how hot it is running i.e a weaker colour will indicate a hotter mixture, or if it is oily it could either be running cooler or alternatively your mixture could be too rich.

 

Spark plugs aint really the easiest things to read as all it is telling you is the temeprature of the plug not the state of the engine. I wouldnt mess about if it may be too hot as you could cause serious damage. However if it is in the middle of the range I cant see it being very hot which would be where the problems lie.

 

Hope that helps

 

Alex

[Rally Slag 0]

yeah thats why im asking dude, i dont wana kill the engine or damage anything so i just wanted to know if anyone else would be using a plug similar to mine