Thinking of changing sparks plugs. Been looking around and come across NGK Iridium 9.

Those sparks recommeneded for our cars/engines have a 6 rating.

And I was considering buying plugs with 7 rating as they are colder.

My question is, are there any ill-effects with going colder plugs? Will the engine stall or idle funny?? I'm not sure so I'm asking. On top of that, anything else to be looking for?

Appreciate the response guys.

Cheers.

Hey Guni,

Before you go and change the temp of your sparkplugs, you need to check that your plugs appear to be burning too hot or cold for the fuel you consistantly use.
To do this, just remove each spark plug to get an idea of roughly how well they are burning the fuel, and look at the colour of the electrode and ceramic base:

http://www.spark-plugs.co.uk/pages/technical/diagnosis.htm
http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html

Work out from these links how hot your plugs run, and if you need to go hotter or colder or stay where you are. Remember that NGK and Bosch work opposite with their temp ratings!
I have tried Iridium before, and found the investment to be a waste of time on my older car. So I just put Splitfires on my TX3 Turbo, and haven't looked at the plugs on the Stivo yet.

Good luck,
Gav.

Plugs in car is Denso IK20 which is recommended for the engine.

Looks ok to me ..... but who knows.....