Spark plugs for 3.9 V8 RRC?

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MikeV8SE

MikeV8SE

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Hi all,

Very quick couple of questions, if you don't mind - looking to replace the spark plugs on my RRC 3.9 V8! 3 questions:

1. How often should they be changed? And do I need to change the leads at the same time? (OK, that was 2 questions in one - sorry!)

2. What model do I need? Paddocks list RN9YC, RN11YC and RN12YC, all for 1986-1994 Range Rovers! All for 3.9 V8 EFi, and all either genuine LR or Champion!

3. Whichever model I need/go for, are the genuine LR ones worth twice the price of the Champions? When you're buying 8 of them it adds up!! :D

Cheers :)
 
Jai - that's not on the list!! ;-)

James - sounds expensive - leads maybe, but are the other bits really necessary?

What's the difference between the different plugs then?
 
Mike if your gonna change plugs you may aswell fit new leads rotor arm and dizzy cap al least you know that from the coil the HT side of things should be in top notch. Theyre not all that expensive I wouldn't have thought. Unipart used to do a nice lead set for reasonable money but I think t hey have died now days
 
BPR6E is an NGK plug BPR6ES is a colder plug (I THINK). Either will do.
Pop down to Motor Parts Direct. Asheridge Road.
Thats where I get all my bits from . Filters plugs Oils etc.
 
magnecore or genuine leads or your wasting your time, regarding plugs:

Two camps here , NGK or champion both worked ok for me but people report problems with both.

the worst I have heard about and experienced were bosch super 4's . it wrote off one engine so steer well clear as there is no advantage and they cost more and at least the others wont do that!
 
the worst I have heard about and experienced were bosch super 4's . it wrote off one engine so steer well clear as there is no advantage and they cost more and at least the others wont do that![/quote]

Thats interesting to know. Why are the super 4's so bad? only ask as i was concidering them when I get round to changing mine.
 
What were the circumstances surrounding the damage??

last time i went to the factory NGK and Bosch were on the same production line right up untill the labels were put on......;)
 
well two peeps I know of , one being myself bought a set and had trouble with missing after a few hundred or miles or less, swapped em out for normal ngks and all was well.

Another guy I know put them in and after a few hundred miles the broke up and wrote his engine off , he had to sue em and halfords for a new lump but I dont know how he got on.

when I took mine back the guy at the shop said yeah we have had loads of problems with these, we are gonna stop sellin em soon :eek:
 
I run my RRC on Bosch Super 4's no problems at all. I think the plugs causing internal engine damage is where the plug electrodes wear - the 4 electrodes are small and can be eroded to a point where they can "drop off" or at least that is what I understand. I suspect the answer is to check your plugs regularly and change them at the appropriate intervals - I think 10,000miles is probably about right but most modern plugs in an engine running correctly will do more than that.
 
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