Well I must say I have never been a lover of Champion plugs but this does
seem a bit of a drastic failure.
The ceramic might have had a crack in it but its a bit odd that it lasted
15K miles. Have you had the plugs out recently?
The reason that I dislike Champion is that in the past on other cars I have
problems with the Champion plugs braking down and the spark occurring inside
It might be that you have had the same problem and its just broke down the
Most mechanics and engine builders I have used always recommended NGK on the
basis that they often get an odd bad Champion plug. However, thats based
the quantity they buy an individual may never get this problem.
They also say that they have never had the problem with NGK plugs! Nor for
that matter have I.
My little beastie runs on special Racing Plugs not cheap at over ?25 for a
set of 4 but they certainly do the business. Champion as far as I know do
not produce Racing plugs! I doubt you would find an engine builder of the
performance output of my Cosworth Caterham recommend Champion.
The engine in its original 165 bhp spec. came with Champion plugs but after
going through 3 sets in 5000 and the having the problem I have described
above I changed to NGK (warrantee on the engine finished). The NGK’s were
changed every 5000 miles after that, more as preventive maintenance, with
the engines revised output I would never ever fit Champion.
So in keeping with this I run the Sovereign on NGK.
As with lots disposable items on a car you do wonder if the recommended
Manufacturer is more based on Manufacturers discount rather than the items
A good example of this is when I bought the Sovereign then 3 years old at
the end of the years warrantee I fitted Pirelli P6000 and when it was in for
a service just before the warranty run out the service manager commented
that I had not fitted the recommended Jaguar tyre (I have forgotten what was
fitted originally). I told him that they greatly improved the handling but
he was unimpressed. One year later in the showroom all cars were using
P6000!! I am not tying state that this was effected by me, all manufactures
of tyres get the lead on the competition now and then. The little beastie
is fitted with Yokohama A032 and no way would I consider fitting them to the
Jaguar … well I might if I raced it but they are so soft that you would be
lucky to get 3000 miles off them! As its mostly road use on the 7n they are
good for 12000 miles+.
Black 1992 4 litre Sovereign 87,000 miles
200 bhp 1700cc Cosworth BDX 1988 Caterham with Brooklands, Quaife 5 speed
box 50,000 miles-----Original Message-----
From: email@example.com [mailto:firstname.lastname@example.org]On
Behalf Of Edwin G. Dooley, Jr.
Sent: 25 November 2001 16:35
Subject: [modern] bad Champion spark plug
Hello Jaguar friends,
I had a scare with my 89 Xj6 Saturday afternoon - thought I’d finally
blown the head gasket or worse at 192.5K. I started it up in the driveway
and after a minute or so it started missing and making a BAD mechanical
hammering sound under the hood.
On opening the hood, the plug boot had blown off cylinder no. 5. The
cause was the material cementing the ceramic insulator into the spark
plug body had disappeared, with the result that some or all of the
cylinder contents were entering and exiting around the spark plug
insulator rather than the valves. That ceramic piece getting slammed up
and down makes a heck of a racket! I suppose I was lucky that the plug
didn’t disintegrate completely and go down in the cylinder. What a p*sser
that would have been!
The plug was a Champion RC9YC and had about 19 month/15K miles on it so
they were overdue for replacement. I replaced all of them with Autolite
No. 3924, and then replaced all of the plugs on the 90 VDP with more RC9
Champions. I’ll compare the two types over time to see if any info about
the relative performance/longevity of the two types can be gleaned.
Fort Smith, Arkansas
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