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I would only fit Iridium plugs. I run them in my own cars and also many of my customer's cars. After I put them in my Shadow I found it started easier when cold, and generally ran smoother. They can last much longer than normal copper plugs, so over time the higher initial cost works out to be cheaper in the long run. Use NGK BPR5EIX or Denso 1W16.
 

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Ally,

Far be it from me to contradict Mr. Walters, as he's helped me a great deal, but there appears to be a wide disparity of opinion on whether iridium plugs are necessarily the best for older cars. Jim and others argue persuasively that they are, while John Robison and others argue persuasively that they may not be.

A lot depends on the current condition of your engine. If it's out of tune and fouling a plug or plugs I'd definitely use a conventional copper-core NGK plug until you have any issues sorted out.

I've got a set of iridium plugs that I've never put in yet because I don't want to lose a set to fouling and the engine in my car is currently a tuning work in progress.

You may also be interested in this thread on the RROC-A Discussion Forums if you are not already skilled in getting your plugs out or back in, particularly B3 and B4. That is addressed at length later in the thread.
 

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Spark Plugs

Copper core plugs are fine but a lot depends upon the condition of your Engine and Ignition system ,also what sort of mileage you do and the type of Journeys ,if short then I would go for Iridium if your car is in good tune if not then stick to copper core for fear of fouling,if using the car for longer runs then go with the Iridium ,they are Expensive but last much longer and give better performance .
 

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My experience with fine wire technology plugs (platinum, iridium) has been contrary to what Brian and Bentleyboy have posted. If you are having any issue with normal plugs fouling I suggest you try them. My personal experience with one of my cars sold me on them years ago. I have owned a 1959 Berkeley since 1974. It has a 2 stroke engine that runs with a 20:1 oil mix in the fuel. For the first several years I owned it every time I started it a plug would foul. When platinum plugs came on the market in the 80's I tried them, and the difference was like night and day. I have never fouled a plug in it since then, and I did not change the heat range of the plugs either. Pretty well had the same experience with an XJ12 that used to be my daily driver, it was difficult to start and would sometimes foul a plug on a cold start. As soon as I put platinums in it those problems vanished. From what I understand of them, the use of iridium allows the electrode to run hotter without damage, which burns off any carbon that does deposit on them. Also, it requires less energy for a spark to arc from a fine wire, so you can run with a larger gap. This results in a larger spark that ignites the fuel/air mixture better. I tend to be very skeptical of manufacturers claims, but personal experience has convinced me that fine wire plugs are worth the extra cost. I have iridiums in my Shadow, and I noticed a positive difference in both starting and running after I installed them. I personally don't care which plugs you use in your car, but you might find them to be a better choice. As their life is up to ten times that of regular plugs, in the long run they can be better value for the money.
 

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NGK copper core all the way. I've had good experience with these in most all of my older/vintage cars.

I do all the work on my cars myself, and have done so for 35+ years....not some paid mechanic...so my experience is first hand here. Platinum/iridium plugs have been the source of some poor ignition issues so I just don't touch them now.

Of course, individual results may vary.....
 

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My Bentley is the first car I have had with iridium plugs. I believe the old ones I replaced last year were the originals at over 70K miles! It is stated to change them at 60K intervals and I know for a fact they haven't been changed in living memory so I was quite impressed that she stall ran as well as she did. I changed them for more iridium plugs as that is what Bentley say should be used... good enough for me.

I will say that the front and back plugs on the passenger side (rhd car) were the absolute pits to change and I have many scars from the experience that will be a constant reminder of my undying love for the hated old dollop!

I also changed the air filters (two joined together in the right hand side wing) and I fear these were also the originals... my fuel consumption with these two changes improved from 10mpg to 14mpg in one fell swoop! Not bad for an outlay of £120.

Please note: NGK are the only plugs I will ever use. Used them throughout my biking life and always been very satisfied.
 

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Original Bentely recommandation for our turbo cars were platinum spark plugs, then they moved to iridium.

Iridium is used in fountain pens. The point of the nib, which deposit the ink on the paper is in iridium in quality gold nibs.

Jean
 

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1993 Bentley Brooklands LHD imported from California
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Hi, does anybody have any experience with Denso W16TT plugs? Is there any reason to use recommended NGK 7149? I have 1993 Brooklands with 6.7 engine. Denso plugs should not last that long as NGK but overall performance should be better. I am using my Brooklands as one of many cars thus do not have big mileage over the year thus thinking to use Denso.

Does anybody know suitable ignition cable replacement? Have hear about using cables from 6 cylinder Mercedes but unsure which one.
 

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NGK 7149 = GR4IX ( Iridium) , replacing the original recommandation BPR5EVX ( platinum)
This is for SZ cars, except Turbo cars ( BKR5EIX / iridium)

Why would you not follow Bentley recommandation ? Price is not excessive indeed for such an engine which desserves the best quality. They last very long mileage and years, you may have sold the car before replacing them !

Be carrefull indeed for fake spark plug sold on internet:

 

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1993 Bentley Brooklands LHD imported from California
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Thank you for prompt response Jean7!

The shop I use to order parts does not have those NGK but offers replacement Denso. Of course I can order them from other shops. Denso also has more attractive price and I am running and maintaining 10 cars thus if there is comparable replacement then some savings are welcome.

I am new with Bentley but I am using Jaguars and other cars for more than 20 years and never had problems with other spark plugs. Maybe I am wrong but although Brookland's engine is really huge then it is low power, high torque and low RPM engine and I am wondering if there can be measurable differences between recommended and alternative spark plugs. But yes, in the end the price difference is negligible!

Thank you very much for fake plugs warning!!! I will focus on it!
 

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Just bought new spark plugs... NGK GR4IX, as they are "official" replacement of originals for my car in NGK catalogue. Interesting, that they are specified only for model Eight 89-93. Is it due to lack of turbo (?).

Anyway, I checked also Denso catalogs and noticed, that Denso specify spark plugs IW16 for old RR/B. Not IW16TT. For all other cars IW16 and IW16TT are interchangeable, only for RR/B not(!). The only difference that I see is, that "TT" have 0,5 mm higher ground electrode. Maybe it matter.
 

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I just put a set of GR4IX in my 86 Spirit They run great

Also I have found that a set of NGK ignition wires that fit a big block (427) Corvette fit the 86 Spirit just fine I did trim to length 3 leads that were too long to look good under the hood. The angled plug ends fit perfectly. They are 7MM wires to fit in the loom holders along the heads. I found that a little DC4 jelly (dielectric grease) rubbed on the outer sheel at each loom holder allowed the wires to be pressed into the holders without ripping the silicone wire shell which evedently was my cause of misfire from a previous owners work.
 

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Hello, based on what I am reading here I see that NGK BKR5EIX (6341) is for turbo cars but NGK catalogue recommends this spark plug also for non-turbo cars. Do you have such type in your non-turbo cars?

Above recommended NGK 7149 = GR4IX is not listed below.

Rectangle Font Parallel Screenshot Technology
 
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