Introduction of inlet manifold C.4953 on XK 120

Various sources claim that Inlet manifold C.4953 was introduced from engine number W.1251 (February 1950). There are sincere doubts whether this date is correct. I collected some information on this Inlet manifold and wrote it down (see below). I would appreciate comments on the conclusion. Also owners of an (original?) 1950/1951 built XK 120 that have the predecessor Inlet manifold C.2377 fitted, are invited to comment, mentioning the built date (month) of their car.

(Unfortunately I still cannot upload files or photos; tried everything but no success so far).

Bob K.

Jaguar XK 120 Inlet manifold C.4953 for 1 ¾ ” SU H6 carburettors
Inlet Manifold C.4953 had been developed for the October 1950 introduced Mark VII Saloon. A vacuum port at the bottom rear end of the manifold was required for the brake booster of the Mark VII, as were two upper tapped bosses to support the Mk VII Air Cleaner. The same Inlet manifold was also used on the XK 120 that so far used Inlet manifold C.2377. For application of Inlet manifold C.4953 on the XK 120, however, all these holes were not required and therefor plugged with Brass Plug C.799 or a chromed 3/8" bolt.

Jaguar had two supply sources for Inlet Manifold C.4953: William Mills Ltd of Wednesbury and West Yorkshire Foundries of Leeds. They can be easily recognised having different casting marks.

Inlet Manifold C.4953 made by West Yorkshire Foundries Ltd is marked D 180 .
This version has only two brass plugs: one at the lower rear (vacuum port) and one below the rear carburettor (water channel). Some very early versions may have no vacuum ports, not for the (Mk VII) brake servo, nor for the Trico windshield washer.

Inlet Manifold C.4953 made by William Mills Ltd is marked WM 2724 .
This version has 4 brass plugs: one at the lower rear end (vacuum port), two below the rear carburettor and one below the front carburettor. It also has the vacuum connection for the Trico windshield washers.

West Yorkshire Foundries also manufactured the earlier Inlet manifold C.2377 as used on the XK 120 and apparently kept the casting number D 180 when the above modifications in the tool were made and the Jaguar code number was changed in C.4953. This was possible as the overall design of the manifold had not changed and they only had to add the two bottom ports and the top bosses for the Air Cleaner.
We assume that the West Yorkshire Foundries manufactured Inlet manifold was initially intended for the Mk VII as the Mk VII SPC refers to the use of two Brass Plugs C.799. The XK 120 SPC refers to four Brass Plugs C.799 which clearly refers to the William Mills manufactured version. But the Manifolds are fully interchangeable.

Time line
Inlet manifold C.4953 was used on the Mk VII with A prefix engines and up to B.2916 over a period from early 1951 (start production) till 1952.
The introduction of manifold C.4953 on the XK 120 is often referred to as “from engine number W.1251” (February 1950). The XK 120 SPC refers to the use of certain Studs after engine number W.1250, but there is no clear relation between these studs and the new Manifold C.4953. These new studs relate to the introduction of the new Water Outlet Elbow, not the Inlet manifold itself.
As the new Manifold was first used during the start of the Mk VII production in early 1951, it would not be logical to assume that it became available for the XK 120 by February 1950 (one year earlier).

Hence, we assume that Manifold C.4953 was introduced on the XK 120 in early 1951.

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Yes, there certainly is a case of misreading the SPC. Another Viart error, pgs 209, 212

No indication is given of an engine number demarcation for the change of manifold.

The studs however, changed after the first 250 heads because of the change from the oblong otter switch with 2 screws to the triangular otter switch with 3 screws and consequent change of the top hose elbow.


The C.4953 manifold can be easily recognized by the two unused screws above and to one side of the carbs, and two or four large brass plugs underneath. The plug at the extreme rear at the intake port for #1 cylinder is replaced by a hose fitting on Mark VII for a vacuum hose to the brake booster.




The C.2377 manifold can be easily recognized by the lack of those two unused screws above the carbs, and only one large brass plug underneath the rear carb.

As to an introduction date for the manifold, we are left to guess.
Only one Mark VII is recorded by JDHT as having been finished in Dec '50.
The brake booster seems to have been fitted from the first Mark VII. It is listed in the SPC and mentioned in the first brochure.


We make an assumption, unsupported by documents, that they would have used up all their C.2377 manifolds on XK120 engines, while building Mark VII engines with C.4953 manifolds, and then started using C.4953 manifolds for all engines.

Another factor to be entered into the investigation is heater hose fittings. Did the C.2377 manifold have a plug at the back, where later there was a hose port for the FHC heater?
Mark VII had a banjo on the manifold for a heater hose, but I think it was on the bottom.

So until more accurate information is found, the early part of 1951, when about 1700 XK120s had been built, seems to be the best guess at this time.

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For your research.

660752 - engine W3017-7 - completed 18 April 1951 (Thanks Terry) has C.2377

The car had been dismantled and previously may have had parts replaced but overall given it’s a matching numbers car I imagine this inlet manifold would be original.

Excellent Jason, this is how we ferret out these obscure details.
So you have a clearly marked C.2377 manifold, but it has the bosses (unthreaded) for the Mark VII air cleaner screws (red arrows), and the plug at the rear where the Mark VII vacuum hose fitting would go (green arrow). Both of which are not found on earlier C.2377 manifolds. We have to conclude this is some transitional casting, a previously unknown, but not entirely impossible situation.


I think I also see a plug where the hose port would go on later 120s with a heater (blue arrow).
Now it’s got me curious, what is the plug at the yellow arrow for, if earlier manifolds had it?

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Jason,

Thanks for that information. So my assumptions seem to hold. The XK 120 apparently still had the “old” manifold in April 1951 . But yours is (like Rob mentions) an “intermediate version” with the double plugs at the bottom and the mounting bosses for the Mk VII manifold already in place.
It also explained why West Yorkshire Foundries later only changed the Jaguar part number but kept the casting number D 180.

Bob K.

Rob,

I had to re-thread one of these plug holes (I have the William Mills casting with 4 plugs) under the rear carburettor and there’s only a water channel down there. I also wondered what purpose these connections might have… Another heater connection?

Bob K.

I believe I have one (totally bare) of those C.4953 manifolds on the garage floor,
after selling a complete one with carbs on it recently, which came off a '51 MK7 block, engine number A15xx

Better remember to slip that manifold onto the engine before I forget, and check it is a C.4953

My XK120 (660405, built 5 Dec 1950) has engine number W2604-7 and has the early C 2377 manifold with no threaded bosses for attaching the Mk VII air cleaner. Some PO had drilled and tapped the welch plug at the rear to accept a fitting for an added servo (now removed). I plan to re-install the original-type plug at some stage. I can’t comment on any brass plugs underneath, but one of my next jobs is to remove the manifold to fit the new longer studs to accommodate the thicker heat spacers between carbs and manifold, so I will check then and report back. BTW, these are old pictures - things look much better now!



A more recent picture. A heater was fitted on 29 August 1952 by Jaguar for the first owner. In addition to this they also fitted a wing mirror and an HMV 4200 radio and aerial - total cost £59 15s od.

So if the plug at the yellow arrow is water, it must be for a heater hose banjo on Mark VII.

I suspect but am unable to confirm that D180 is the aluminum alloy spec. in the old British system.

Rob,

In the 1970’s up to the 1990’s, the British factories I was involved with used LM6 aluminium casting alloys. As far as I remember all aluminium alloys started with an L.
I guess D 180 is the casting tool number for the WYF manifolds. Possibly D for Die-casting.

Chris,

Thanks for your input. So we have your manifold (at this moment) as the last C.2377 in an unmodified execution, dating from December 1950 and made by WYF.
Jason reported a “modified” C.2377 manifold dated April 1951, also made by WYF… So, we’re beginning to see a time line (but too early to conclude that this is it).
Tony reports he probably has a C.4953 manifold from a 1951 Mk VII, which also fits in the overall time line.
I wonder whether William Mills ever made the early C.2377 manifold! Could be that the expected much higher production volume of the Mk VII, made Jaguar decide to opt for a second supplier and WM only made the later manifold…

Bob K…

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C2377. No foundry mark that I can find. Unknown origin and I don’t know who polished it, or when.

here is a couple of pics…

This comes off engine A5951-7 its a MK7, a '51 I am pretty sure
Has an SH gearbox (from memory) on the back (suits XK120)

Note I did did sell the original complete manifold with all attachments and carbies, that was actually on it, this was a loose manifold sitting next to it, the manifold on the engine was able to slip right off, and I think I he got a good buy, it was the same, but this one is bare

The entire lot is for sale, it has the cam covers with no front studs, I also have another set like that, (a good upgrade for any early XK owner with the wrong cam covers)

I havent advertised it yet on “classifieds”, but I will soon

My early Mk7, car no 711124,has a C4953 manifold.

Tony, a little research indicates that this manifold is from an XK140. Probably also late Mk VII and maybe Mk VIII? Quite a bit different to the XK120 manifold.

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Just confirming, Tony’s C7462 manifold is for all XK140 and later Mark VII from engine B2917 onward, other than specials with 2" carbs.

Randall, your C4953 manifold is as expected for early Mark VII A and B engines up to B2916. I imagine it shows how those two screws were used for the air cleaner.

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To all

So based on the dates we have found so far, the time line of early Inlet Manifolds could look like this (only XK 120 and Mk VII are presented here, but XK 140 could be added).

Bob K.

yes, my bad, I misread the stamping in the manifold and ignored the raised cast part num :grimacing:

Yes mine has the two screws for the air cleaner

Just as an aside, I note that Bob’s table shows no Mk7’s listed in 1950.A friend of mine from Cpe Town had car no 710525 which was purportrd to be a 1950 model, it had a diffetent block with an extra small welch plug higher up on the exhaust side. It was re-exported back to UK by his son in law some years ago.

That extra welch plug is one of the features of an early C2331 block. I wonder how the front engine mounts were arranged on a Mk VII with this block, as there are no threaded bosses for the later Mk VII (and XK120) engine mounts. I thought the reason for introducing these was that the Mk VII had a different chassis design in that respect?