Replaced Standard Spark Plugs With Iridium

I have just received a set of new iridium spark plugs from the Bigjimny store and replaced the cheaper champion ones. I fitted the cheaper ones on the last service and didn't notice any difference but now I have put a new set in ill see if it runs any smoother or if there's any change in fuel consumption.

I took it for a long run tonight and found the 'kangarooing' has stopped, originally I thought this was because of Prop UJ going. So I will stick with the iridium plugs in the future.

The metal in a spark plug serves a single basic purpose: to channel the electric energy from the plug wire through the spark plug so that it can be forced to the engine block in the form of a spark. Therefore, any metal that conducts electricity at all could potentially be used for a spark plug. The metal should also not get too hot; one of the main problems with some metals is that they overheat quickly, causing the electric charge itself to be compromised and the spark plug to not operate as smoothly.

Copper spark plugs are generally considered to have the best performance of any spark plug type. This is potentially different from what advertising companies suggest, but the other metals are, unfortunately, not as conductive in general as copper is. Platinum and iridium plugs are more likely to overheat, which causes damage to the plug components and can compromise the delivery of the spark to the engine block.

Platinum and Iridium plugs perform at a lower level than copper spark plugs, because they are less conductive and they tend to overheat. However, the overall longevity of these two types of metal is better than copper plugs. In reality, copper has the best performance of all three and the worst longevity. Platinum has good longevity and the worst performance. Iridium has good longevity and a performance that is decent, which is why iridium plugs tend to be more expensive than any other type. Still, the difference between these plugs in terms of overall quality is minimal, as there is a trade off for each.

Most copper plugs need to be changed every 20,000 miles or so. Platinum and iridium plugs can often go for twice that before they require changing, but the overall performance will not be as good and you may have to deal with overheating of the plugs. This is potentially not worth the added cost of both platinum and iridium spark plugs, although the decision will depend upon your preference.

I run iridium in mine and have not had any problems with over heating.

Thanks for that Rappey

11/60 wrote: I run iridium in mine and have not had any problems with over heating.

Im going to stick with these too.

The standard plugs in a Jimny (M13 engined ones at least) are iridium. As Rappey points out, there is no performance advantage to iridium over copper. It is simply a matter of longevity. Any change in performance noticed when fitting new plugs is more likely due to the old plugs having deteriorated beyond their efficient working limits.