I’m a visitor here as my earliest car is a 1962 vintage. Taking said 1962 car for roadworhty inspection last week my old school garage guy produced the attached shipper of 10 Champion N8 spark plugs from a very large carton he had sitting on the bottom shelf in his workshop. He knows that they are for Jaguars but unsure of model. I know that they predate my car which calls for N12Y series. They are circa 1985 per the box. Does anyone know the appropriate Jaguar model? Thanks in advance. Paul
N8 is quoted for the MkV 2.5 litre
The Jaguar equivalent part no. for the N.8 was C.1638 in the Mark V SPC, and this same no. is listed for 2-1/2 L Mark IV, although the Champion no. was given as N.A.8 and described as “Long Reach”.
So it may be suitable for 2.5 Mark IV with P series engines after P201.
It would apparently not be suitable for my 2.5 SS which had L.10.S plugs.
I don’t think the thread length in the head changes SS through to MkV. I think they were just experimenting with the differences in firing given by the rather socketed 1/2" reach L10 and the later 3/4" reach N8/NA8 types.
The NA-8 BLACK BODY Champions were OE for the XK120s… These are very rare now and generally only the serious OCD folks ( like me ) are prepared to stump up what they cost… last set I sold flew off the shelf to the Healy guys who’s cars also use them for $100.00 each. ( $600.00USD /set ) I have yet to sell a set to a jaguar owner… go figure. there was a set of NOS black body N-8s on offer on e bait a few weeks ago… but they didn’t sell at 30 quid for the set.
Thank you gentlemen. I will let him know. Perhaps he will list on eBay as well. Regards Paul
According to a well-known military PhD who used to post on J-L:
“Those plugs have a NATO stock number on them, Bet they are for a scorpion or some British Military veh. Those numbers are unique and allow ordering across national systems.”
For my part I would only say that N8 is a pretty ‘hot’ or ‘soft’ grade. That’s fine for burning off deposits and staying clean in an engine running at low stress and on poor fuel but I’d be wary of using them in a high-revving sports engine.
Suited to chugging along, usually below temp and operating well below the designed performance envelope? Sounds ideal for Healeys and XJ220s…
Confirmed by some other reading I did. Apparently suitable for some series of 7:1 compression Land Rivers. I think you’re right, at least about the Healeys.