They are pretty much standard offering on Caterhams and are a good plug.
Dave
hello all, i’ve found the right answer :
http://www.ngk.com/results_appNonUS.asp?internationalMotiveID=1698
hope i’ll be good for everybody.
sorry for my bad english !!
B.
personally I use Bosch FR56 (available cheaply as a set of 4 in many continental supermarkets) on my K series and am very happy with them. Fitted also to a friend’s VHPD with good results.
(good results means the car starts fine even with weak battery and cold weather, I doubt there is a power output difference)
[quote=pete757]Thanks…
Recently spoke to the very helpful guys at PTP and they use and recommend NGK BCPR7ES in all their VHPD engines.
(Google tells me that this plug is also used by SAAB in their HP Turbo engines!!!)
Cheers,
Pete. [/quote]
Hmm, I’m not sure about this. The “6” heat range on the RC6YCC champion plug equates to an “8” heat range in the NGK system, according to the cross reference charts I’ve read. The “7” in the plug you listed indicates a hotter plug, something I’d not want to go to as you risk detonation.
It’s the same reason you’d not go to a hotter “7” range plug in the Champion range since this is a hotter plug also (and what the stock 118bhp Rover K runs).
Having said that^^^ I just went to my local motor factor’s and looked in the NGK catalogue and they don’t list a conversion for the RC6YCC. However, they do list a conversion for the RC6YC (so single copper, not “double copper” as the Champion one suggests. This part is an NGK BKR7E. Looking at my old plugs and this new one, they look identical. The tip/insulator dimensions etc all look exactly the same so I’m guessing it’s the right equivalent after all.
Incidentally, the heat-range conversion I used was here on the champion sparkplugs website:
I can’t vouch for its accuracy though.
I use NGK Iridium BKR7EIX.
Aah ok, that’s basically the iridium version of the plug I have. I also note they do a “8” heat plug which is a notch colder which might be the go 
Just thought I’d resurrection this old thread.
Interesting to see some of the old “issues” here again!!!
I’ve been having starting, over-revving at idle and then mis-firing problems that I’m trying to sort out by taking as much out checking and then putting back in again.
Recently had the spark plugs out - the Champion ones as recommended in the handbook (typo not withstanding!) and found that the gaps they were set to were much wide:
so following on from banned advice earlier this must give me an extra 16bhp or perhaps more realistically has given me a weak spark that has made cold starting more difficult. Anyone any thoughts?
I think the plugs themselves looks fairly healthy: