Extremely interesting, and equally interesting how one can get drawn into exploring such details. I can see that the human behavior factor in the early manufacturing process plays very heavily in tracking down details, as the workers’ state of mind and attitude that particular day back then would impact how compulsive they were in stamping, recording, and even machining the heads/engines.
This really makes the cars into almost living individuals, as opposed to cold, mass produced objects without a soul.
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Were sand-cast bells, on the SUs, used in early production?
Wiggles,
By saying ‘sandcast bells’, presumably you are referring to the larger 2inch model H8 carburetter, that had Sandcast ‘Suction Chambers’
These were introduced in 1952 for the C-type racing car, and were also rarely offered as an aftermarket spare part for those racing all manner of cars including a special set-up for the XK120. THey were never factory fitted option on XK120s, albeit through the 1950s and 1960s a number of XK120s did have C-type heads (ex XK140) and H8 carburetters (ex XK140 or new spares from SU or Jaguar) fitted as a performance upgrade.
Al XK120s left the factory with H6 carburetters (a smaller 1-3/4inch model) that had smooth/polished ‘Suction Chambers’, but there was an evolution in detail over the 1949 to 1957 XK120 and XK140 period.
I am trying to resolve exact demarcation of all changes, and indeed also the exact original finish of all parts - for instance the ‘bright-parts’ were originally Dull Nickel plated, but later onwards (exact month unsure) most bright-parts were then Cadmium Plated. Some parts were originally ‘blackened’ and then Cadmium plated later, and so on. A lot of detail to resolve.
This is my interest in getting photos of original carburetters and inlet manifold - whether original H6 or indeed even if aftermarket modified H8. I have done a huge amount on both H6 and H8.
Indeed if anyone has or knows of a ‘spare and available’ H8 - I only need one, but happy to get a pair - I would be interested. Trying to put together a complete ‘original’ twin H8 / linkages/ manifold/ air-cleaners/ choke set up for my XK140, and have just about everything now, except for a second H8.
Roger
My parent’s Silverstone (LT-2) had the cast suction chambers, and if I ever saw a ‘49-52 120, the memory is lost to the ages!
Thanks for the info!
Good morning Roger,
Sorry. I’ll send the pics of carbs and manifold today ( promise!).
Best Regards
Nigel
Nigel I would love to get some more and closer pics of that number on the back of the block to confirm exactly what the prefix is.
I would also love to get the numbers stamped into the top flanges of the carburettors where they bolt to inlet manifold it will be a letter and number 1-12.
What car is this motor going into?
terry
tmcgrath@bigpond.com
Ok Terry
Maybe tomorrow? Off out to NEC Birmingham Auto sport show today.
Nigel
lucky man was there myself back in 1993!!!
Many thanks Nigel,
From these photos I can basically identify carburetters, but as with head, the devil/interest is in the detail.
On top of the flange(s) where the carb body bolts onto the inlet manifold, for both H6 carbs of course, there should be stamped in a letter/number code. In your photos I cannot read that, as resolution insufficient when I blow-up pic. Can you please advise this letter/number code on both H6, and if possible a clear photo would be great.
Similarly on the rear-side of both main bodies, there is a cast in ‘466’. Very faint and alongside will be an etched number. Again if you ‘carefully’ chemically clean the area, it will be easier to see, but don’t clean abrasively as this all important etched number can easily be removed. Again a photo would be best, as the faint etching can be difficult to read unless you know what you are looking for.
Many thanks.
Lots of good detail in all these photos, of a very very early XK120 engine.
Roger
Also worth noting is the first generation manifold which lacks some features of later manifolds such as threaded bosses on the upper half and an extra brass plug on the bottom, which were provided for use on the Mark VII.
There are several of us on this forum who take an abnormally keen interest in such details.
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Hi Roger
I’ll degrease them today and see what’s more visible then, if still not clear I’ll do it after rebuild when they’ve been sonically cleaned.
Best Regards
Nigel Boycott
I’ve been reading through this thread with much interest! Perhaps somebody can help me with some numbers on my early (Dec 1950) XK120 engine, which is currently undergoing a full rebuild to standard specs at Brian Stevens’ XK Motorsport in Hampshire. Main components are back from the machinist’s and I’ve taken a few pics of various (but not all) casting numbers.
The engine number is W2604-7, and the bock is the early C2331 without the mounting bosses for engine mounts, threaded holes on RH for coil mounting, extra small core plug above centre core plug on exhaust side, etc.
The crankshaft is the early 6-bolt flywheel flange type - C2239. Stamped on the front counterweight below the part number is what looks like 3 (or 8?)OFY69B. Does anybody know how to decipher the meaning of that number?
The cylinder head is a later replacement - C12500, which I think makes it an XK150 or Mk VIII head? Also cast near the part number are C697 and also B680. I don’t know what these mean…
Sump is the early full-length depth C2359, and the inlet manifold is C2377, while the SU carbs are both stamped F11 on the mounting flange. Short dashpot type, early thermo starting carb design.
Many thanks if anyone can help.
Hi Chris
Not sure, but think the cast no on the crank could be some kind of production date for the casting? But don’t know how to read it!
The engine is mounted via a plate that fits onto the font cover mounting bolts. It was subsequently changed and the front engine mountings came off the sides of the cylinder block. This involved the introduction of necessary bosses being cast into the block for provision of the mounting setcrews. 3 on each mounting bracket. I don’t think the early block can be modified to this design.
Hope this helps
Best Regards
Nigel Boycott
Thanks Nigel. Yes, my engine is mounted at the front with the plate that bolts to the timing cover.
Best,
Chris
Hi Nigel and others,
I’m replying to this topic since it ads information for other early XK120 owners.
At the moment im rebuilding a very early XK120 engine. Engine number W1388 and sequence number A386. There is very little information available and since I didn’t disassembled the engine by myself i’m in doubt how to reassemble the engine.
Currently the piston bores have been bored and honed, new pistons has been placed, top deck is surfaced and the cilinderhead is completely serviced. At the moment i’m rebuilding the carburetors and on the engine placing the timing chain.
My question:
Is it correct that there is no top chain dampers? Except on the metal tap in the photo below?
Were the float chambers different in the first XK120’s? See photo.
Hi Bram,
The spare parts catalogue shows no dampers for engines before W1914.
Also different front and rear mounting brackets beginning at W1914.
I’ve never seen float chambers with an original hole in the bottom. It looks like the studs were broken off, and somebody drilled the broken stub out and was figuring on coming up with some alternative stud mounting, perhaps an epoxy like JB Weld or something.
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Hi Bram
You have a very early engine there.my advice would be to fit later type chain plates which will let you fit top chain dampers. I had one exactly the same about 2 years ago. At all my time in Jaguar Cars Ltd,engine Reconditioning, I don’t ever remember
seeing ones like this!
The spacers for dampers are available. Not sure if anyone is making new plates.
I would also replace the tensioner adjusting plate. You’ll need to buy a used chain assy as the plunger for locking the adjusting plate is NLA (the later type I mean)
Best regards
Nigel Boycott
Well, here’s a puzzle for the engine sleuths!
My Dec 1950 car has engine number W2604-7. BUT, this number is too late for the block, oil sump, and intake manifold. The C2339 crank fits with this engine number (W1747-W2645) and the carbs are also a good fit, both being stamped F11 (Nov 1950). The block is a C2331 and the last engine to use it was W2011, the sump is a C2359 and W2057 was the last to use it, and finally the intake manifold is a C2377 which wasn’t used after W1250.
I’ve been studying the engine number stamping on the block which I had always thought to be correct, but very close examination has made me wonder slightly see picture below. There are slight signs of file(?) marks on the right corner of the top of the oil filter boss, and there is the faintest hint of a 0(?) above the 6 - or are my eyes playing tricks on me?? However, the slightly rough texture of the casting seems to be intact with no real signs of another number having been ground off. I’m at a bit of a loss…
i will just note…whether early or later…do be sure you have a set of the parts supercede documents, changes made in production, AND the Factory Technical Service Bulletins: …so many parts were revised and many of those revised have to be installed and work together with other revised parts. You can not rely of the Factory Service Manual alone…you have to understand the revisions…some of which MAY have already been done by prior owners…correctly or NOT. Nick