Have to disagree.
Original XK engine valve seats are already hardened steel, thus are totally OK for unleaded fuel.Indeed, unless your original valve seats are unserviceable, then you have greater risk of causing problems unnecessarily replacing serviceable originals. Very few people know how to properly insert new valve seats, and if not done properly high risk of them coming loose with all associated risk of damage.
For valve seats to be done properly you need to properly heat up total cylinder head, thus will need decking due to probable warpage.
And who to say new valve seats, made wherever (China, India, etc) are equal quality steel as the original British steel anyway.
Listen to expert advice, and not that of anyone with a vested interest in selling you parts, or many hours of machine shop work.
Roger
That’s my understanding too. However, I have been advised to modernise the valve guides if I want to reduce oil consumption. Much of a job?
I never knew that they are all unleaded compatible. So, as you say, if not badly recessed/ burnt then should be fine. Excessive re cutting of valve seats will result in it being impossible to attain correct valve clearances without bodging,ie thinning shims or taking material of the top of the valve stems.
Nick,
You will be aware of course that all British engines, including the XK motor, we’re designed deliberately to burn oil. Acted as an upper cylinder lubricant, before anyone cared to much about the pollution aspect of burning oil. RR was worse than Jaguar.With new interest in limiting air pollution, Jaguar simply added valve guide seals, so if guides were not overly worn, certainly limited oil consumption/ pollution.
But the valve guides did wear, but are easily replaced, and if that worn will undoubtedly require new valves to be fitted as well.
When I had my XK140 engine rebuilt, I had fitted quality new valves and valve guides, and fitted to modern tighter clearances, but chose not to fit valve guide seals. But if the odd puff of burnt oil is of concern, it is very easy to fit the standard seals as supplied with any quality head overhaul gasket set.
Depends how many miles you expect to cover, and as per the UK, is there an annual roadworthy check that measures pollution.No annual checks in Australia, unless you can’t see the car because of the smoke!
Roger
Just to kind of finish up the thread that I started (with much appreciation for all the helpful comments posted!) here’s a recent sale of a 1954 non-numbers matching, 5 speed converted XK120 SE. The comments posted in the auction thread seem to indicate a belief that it was “well bought” and that most expected a higher result.
So what have I learned from all of this?
Observation number 1: The XK120 OTS is one of the most beautiful Jaguars ever built (not exactly news to all here!)
Observation number 2: as expected matching numbers cars in the current market usually sell for more money then non-matching numbers cars.
Observation number 3: the vast majority of people who see the car think it is beautiful and don’t really even think or care about matching numbers.
Observation number 4: Key questions for me as a purchaser are (a) “do I want to drive it or do I want to show it?” and (b) “what percentage of my purchase decision is based on investment vs. pride of possession/enjoyment of driving?” ( i.e. higher percentage = investment then that much greater need for matching numbers).
My guess is the person who bought the non-numbers matching 5 speed converted XK120 on Bring a Trailer will have a blast owning and driving (and showing) that car!
And the fact that I’m jealous is a pretty good indicator of what I think of the entire issue…
Chet
Beautiful! Had I the ching—and was about 6 inches shorter!!—that would have made a wonderful sop, to the Silverstone: that was my rent’s race car, during the late 50s to the late 60s.
It, and many other beautiful Jags, can be seen here:
I had my original oil pump refurbished. Chain tensioner upgrades are available from:
Rob Beere
Coventry auto components
Guy Broad
I stayed with the spring blade tensioner, however there is a disturbing article in the November XK gazette where the design of the replacement is called Into question. I have yet to run my engine in (currently in the trim shop) so am a little worried about what might need to be done when I get it back!
Thanks for digging out that video again Wiggles. I’ve seen it before, but every time I watch it I see something new. This time what I saw was quite a surprise. The first 3 minutes of the video were shot in my back yard - literally! The road you see the C-Type driving on runs along the bottom fence line of my property.
Small world!
-David
Hi Phil:
The only time in my sixty odd years of owing the XK120 that it left me stranded was due to a timing chain break and the reason for the chain break was the spring on the blade tensioner letting go. It happened twice, although many years apart. When I had my engine rebuilt I believe the chap used a new blade and spring tensioner again as the parts I had given him did not fit. So far, after 11 years and some 32,000 miles all is good!
Chris.
Many thanks. I’ll be biting my nails for a few months until I get some miles under my belt.
07714 759198
The two areas to watch with regard to oil consumption are valve guides (used modern ones with seals), and high quality multi-piece oil control rings. My professionally built engine used new Mahle pistons with one piece oil control rings and it burned about one quart every 300 Miles. I’ve heard that Mahle admits this is typical for the one piece rings! I used the past tense because it no longer runs because a professionally installed valve seat (Jag specialist), dropped after 1200 Miles.
Obviously, I advise against replacing your valve seats unless they are worn out. The originals were stellite which is as hard as they come.
John
Thank you for the advice, John. About 18 years ago when I was looking for something to do I decided to refresh the head - the engine was free but hadn’t been fired up in 30 years. Took it off, lapped the valves and replaced the springs and cam bearings. At the time I noted some slop in the valve guides but the seats were looking good. No reason to replace them. When I get around to doing a proper rebuild on the engine I will want to put in new guides.
My block on engine W2604-7 only has C2331 cast on it, where one might have expected C2331-1…?