Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Iridium spark plugs

So what I am thinking for a Sigma is Motorcraft AGSF22FSCM, or NGK TR5B-13 with a gap of 1.2mm??

Just to inform anyone who picks this up, Ford decided some time ago that a 1mm gap was the optimum for their engines when using iridium plugs and sent out an urgent internal instruction to their dealers. originally it was at 1.3 mm and was destroying plugs and caused problem running. After several test periods they found that 1mm was the optimum gap for consistency of plug performance and engine performance. For the old school that's 39 thou". I can't remember what they advised as a change time milage but it wasn't anything like the service an iridium plug is capable of and people do get 100,000 miles +with little wear or degradation to the plug. perhaps the problem lay in the fake iridium plugs that flooded the market and still do. If they seem like a bargain then its odd's on that they are fake so only buy from an accredited distributer. Fake's are lucky to give you much in the way of milage and your first symptom will be difficult starting. If you pull a plug you'll find the fake iridium plug will have eroded it's center contact to nothing as its probably made of copper!

Plugs last way longer than in days of old BUT if you have an alloy head, it is wise to unscrew and re -torque every year, otherwise they can become stuck in the head and could possibly lead to major surgery to remove.

If you do that, be sure to change the compression washers as they're a once fit item, if you just keep whipping your plugs in and out to inspect them and or to keep the threads chased but don't replace the compression washers, you will not get the correct seal and your torque reading will be wrong too.

You can buy compression washers from Tim Green at the Green Spark Plug Company, I would buy your plugs from him too as he offers excellent customer service, fast delivery and his prices are very competitive too.

https://www.gsparkplug.com/10x-budget-spark-plug-steel-crushable-washer-washers-14mm.html




My Rover V8 spark plug experience includes 11 years of ownership and almost 100,000 miles driving my TVR Chimaera, this proved you won't really notice any difference between a nickel or iridium electrode, they're all copper core by the way. In my TVR's RV8 I experimented with NGKs expensive specialist platinum chip ground electrode iridium tipped LPG plugs, BPR6EIX Iridium, and good old BPR6ES.

I found I was much better off using BPR6ES and putting the money saved into replacing my HT leads every 2-3 years, I changed my BPR6ES every 7,000 miles which I also felt was way better than leaving a set of long life BPR6EIX sitting in my heads for 60,000 miles. Mr Retro Leads offers good quality sets for the RV8 or you can buy the leads and ends separately from him and make your own set up for a good saving which is what I did, however, to make a proper job of it you absolutely must use a pair of proper HT lead crimping pliers.

Actually, in the end I found the ultimate plug for my Rover V8 was the one hotter BPR5ES, all Rover V8s put a bit of oil into the combustion chamber so running a hotter No5 removed any ash deposits produced by combusting engine oil and the heavy ends present in LPG. I found HT lead failures were largely caused by plug fouling, when running cooler No6's deposits would built up on the centre electrode within just 4,000 miles and to the extent where the current would prefer to burst the HT lead and ground to the head, rather than through the plug's ground electrode as it should.

By switching to the one hotter BPR5ES all the fouling went away, the No5's self cleaned beautifully and lasted 10,000 miles, as the Rover V8 is a low compression engine there's also zero risk of detonation or pre-ignition, I must have done 50,000 miles on BPR5ES changing them every 7,000 miles with perfect results.

I would also advise against using CopperSlip or other anti-seize greases, what people seem to forget is all these greases are adding a layer of insulation which is the last thing you want on a spark plug as a good ground contact with the cylinder head is essential. This is why NGK developed their trivalent plating, this silver or chrome-colored finish on the threads is designed to provide corrosion resistance against moisture and chemicals. The coating also acts as a release agent during spark plug removal, all NGK spark plugs are installed at the factory dry, without lubrication or anti-seize, we should all do the same. Also if you're still worried about plugs seizing in the heads of your RV8 just take a moment to look down the plug holes and you'll soon see the threads always receive some oil creep, trust me that's more than enough lube to ensure your plugs wont pull the threads, just let the head cool right down before removing you plugs and you'll have no issues despite no anti-seize greases being used.

Having sold many hundreds of gold palladium (precursor to Iridium) plugs during the course of my 20 years in motorcycle spares I agree as mentioned earlier in this thread, they make little difference to a well set up ignition system with copper tipped plugs. However when the chips are down (cold weather, poor battery) these fine tipped plugs, courtesy of exotic metals, will spark at a lower voltage allowing starting when copper tipped will fail. The physics behind this being a spark will jump onto or off a sharp point more readily than a blunt surface - think lightning conductors.

I now understand Iridium plugs last longer as well. The service interval on the Ford Cyclone in my Roadster fitted with these as OE is 100,000 miles!

Thankfully, on the Duratec, we don’t need to worry about plug washers as they have a tapered seat.

Thanks Doug, that's useful to know

This is my first Duratec and I'll be giving Monty his first engine service next month. I'm used to the Rover V8, the old B Series and wet liner Triumph engines, so the Duratec is an absolute revelation for me!


Rover V8 exhaust ports....



Duratec exhaust ports.....




Rover V8 intake ports.....



Duratec intake ports......




No wonder I'm able to target over 100hp per litre on the Duratec, but spent 11 years just trying to squeeze over 60hp per litre out of the old Rover. I did eventually get 250hp out of my 4.0 litre TVR Chimaera, but I can't help thinking if it had heads as good as the Duratec it would have been making over 400hp

The Duratec is an amazing thing for sure, with what to me look like race car heads, this is especially mad when you consider it’s an engine found in old Mk3 Mondeos, no wonder its so popular and Caterham are still using the 2.0 Duartec to this day.

I’m really showing my age now aren't I

Dave.

Hi Folks - New to the Forum and Morgan Ownership so I hope you can assist with a question re Plugs.
I recently bought a 1 owner 2006 Plus 4 with 32000 miles on it. Car is immaculate and appears to have been very well cared for by the original owner who, as a retired engineer, did most of his own servicing. I am not sure if the plugs are original to the car and I decided to pull a couple of them to check condition.
The Engine is the 2.0 Duratec. Ford Spec say Iridium Plugs should be fitted and that appears to be what I have however I'm not sure what make they are - Any Ideas? (See Photo Album)

The main point of my question however is the Red Colour of the centre porcelain - I've never seen that before and don't know if its an indicator of engine condition or whether it could have been caused by a petrol additive.
Any thoughts would be appreciated and whether you think its neccessary to change the plugs at this time.

The car appears to run great but I don't have anything to compare it with - not having owned a Morgan before. It starts well too. Is it a case of "If it ain't broke - don't fix it" ?

I can't work out how to post a photo of my plugs so please click on the below link to see my photo album showing the issue.

https://photos.app.goo.gl/ZuG9CRXgwLE6ouop8

Many Thanks for your help

HI, S, Can't access your pictures. have you pulled a plug out or are you looking down the hole! Best tool to remove them is a 16mm articulated magnetic plug socket with a 3/8" drive. Dead cheap on the Bay!
The Duratec engine is notorious for allowing the plug wells to fill with water and stain the ceramic portion rusty red. Various thoughts as to why on this issue! However the plugs have a taper seat not a compression washer and Me, well i'd recommend regular checks to remove any water and service plug seat. I use dielectric grease on reassembly to the threads and plug caps/ceramic body.

To torque the plugs up which are listed at 17lb ft I do not do! If you lubricate a plug or any thread you will alter the torque characteristic and could over torque them and damage a thread so I do it by feel, they really do not need to be strangled into position and it appalls me watching people tighten them like wheel nuts! Well, they probably overtighten them too! I've seen ACF-50 used, sprayed down the hole and that stains plugs a sort of violet colour. Its a great agent to protect against corrosion though. Before I remove ang of my plugs I spray down the plug hole some penetrating oil and leave it overnight. This removes the rusting to the plug metal body then I use an airline to blow them dry before removal, I loosen them half way and then blow them out again before finally removing them for service.

On last thing which I have posted before and that is Ford had issues with Iridium plugs on their engines and finally came back with a directive stating that the gaps should be set at 1mm on all iridium plugs accross the range and this cured the premature breakdown of the plugs. You will probably have information stating that your plugs be set between 1.5 and 2.5mm.

Its a shame Ford ony informed their dealerships about this.

I think they are NGK Iridium plugs. The red colour can certainly be a result of unleaded fuel additives - look normal to me.