Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Iridium Spark Plugs

I don't know if they make any huge improvement ,but I needed to spend some of my pocket money .
Cain was out of stock but supplied the plug spec and I got them on ebey .
They arrived this morning ,now fitted and hope they will last a long time .

Most sparking plugs electrodes last a long time with the cleaner fuels nowadays. BUT, the big issue is external corrosion experienced in overhead twin cam engines like duratech, where plugs may need to be replaced after only a couple of years.

BMW state plug life for the 4.8L V8 is 100,000km = 60,000 miles.
As the wings have to come off to change the plugs it isn't a quick DIY job!

I put some copperslip on the plugs threads , didn't overtighten them and I've got an engine cover to stop water ingress .

It will be interesting to see just how effective engine covers are, besides the aesthetics. I say this because when you look at the multi ribbed, tight fitting plug leads, I am surprised that water gets by. I have often wondered whether it might be more related to condensation forming in the plug recesses as the engine cools.
Any substantive praise out there for covers?

I made a cam cover some years ago out of aluminium that is bolted down to prevent (some) water ingress. . Reason being that, to my mind, the louvres in the bonnet are directly above the “valley” between the cams and moisture will presumably gravitate to the lower area where the spark plugs are located. I’ve checked this area a few times, having removed said homemade cam cover, and all looks dry and corrosion free.

I must say I like the look of the Williams cam cover and may go this route in the near future.

Bob.
Pus 4 Duratec.

Sparks jump off a point source easier (at lower voltage) than a blunt one. This is the thinking behind fine wire central electrodes necessarily made of precious metals to avoid excessive burning. Back in the day gold palladium was the material of choice and I sold many in the course of a motorcycle spares business I ran. Nowadays Iridium is favoured.

They won't improve on a well set up and maintained ignition sytem using conventional copper core plugs, but when the chips are down (damp weather/flattish battery) may make the difference between engine starting or not.

Not sure they will last any longer than the latter either. I remember removing gold palladium ones from my Moto Guzzi and you could see the flame pattern on the tip, as it had melted slightly in that direction although the correct gap was maintained.

I was actually looking for another forum post of the Ford world but then I found the link below.. I also have Iridium spark plugs in the 4/4, I don't know the exact name at the moment. But at that time, around the end of 2014, it was already discussed that Ford had chosen smaller electrode distances than at the beginning of production to protect the ignition coil. So you are on the safe side, but you might give away some performance.

https://www.fordownersclub.com/forums/topic/39946-electrode-gap-on-16-engine/#comment-231065

At that time I noticed that my Iridium spark plugs recommended in a comparison list had a different electrode gap than the copper spark plugs. But I don't know if this was an equivalence value between iridium and copper or if the iridium spark plugs had a slightly larger electrode gap for other reasons.

The last post on this page was interesting for me because I think that this post about Ford corrected electrode gap is younger than my knowledge.
I will definitely check it myself which spark plugs I have because somewhere are still the old boxes or the invoice.
Please note, the 4/4 machine will not be called Sigma in this last post but Duratec 1.6 VCT TI

Do others here in the forum have more current information than I do? That would be very helpful. I would think that the 1.2 mm specified in the last post for standard spark plugs sounds plausible. But I will check this again or call my Ford dealer.
Because with exactly such information it is often better to ask the company that produces the engine and not the company that installs the engine.

Having a wider gap for Iridium plugs makes sense if they spark at a lower voltage, so not stressing the ignition system as a whole.

Older members particularly with bikes may remember the phrase "big fat spark" as in easily seen. If you do the plug out checks for same with modern electronic ignition systems though you may well be disappointed. The lighter colour and shorter duration of spark makes them far more difficult to see in daylight even though the spark voltage is likely greater giving better combustion.

When I changed the OE Ford Iridium plugs on the previous 3.0 Roadster at 50,000 miles they looked like new, really clean tips & ceramics, checked the gap just out of interest and they had eroded just a couple of thou