Xk 140 vs. 150 Engine Block Numbering & Differences

(Mike Loper) #1

I have a 1955 XK140 FHC with a Heritage Trust Certificate. The Chassis No. (S814364), Engine (G3662-8S), and Body (J4565) numbers I have on the car match the published Certificate.
I restored the car, taking everything apart. During the engine removal and disassembly, I noticed the number stamped on the block above the oil filter housing read: V5057-8. The Part No. cast into the side of the block read: C8610 FF.
In “Jaguar XK140/150 In Detail” by Clausager, page 218, the implication I read is that 140 block numbers began with a “G” while 150 block numbers began with a “V”. It does appear that engine numbers started at V.1001 for 3.4 engines (Original Jaguar XK, page 138), so perhaps I’m reading too much into the “V” vs. “G” designations. However, how do I tell if the block I have is indeed the block which came with the engine? Should the number on the head stamped near the #6 cylinder match the number above the oil filter on the block? What are the differences, if any, between the 140 and 150 blocks?
Thanks for any help from the experts.

(Mike Spoelker) #2

The engine numbers are stamped in three places: the commission plate, the front of the cylinder head valley and the engine block above the oil filter mounting pad. When you say “… numbers I have on the car match the published Certificate…” exactly which set of numbers are you referring to? If the cylinder head number matches the commission plate and the heritage certificate but not the number stamped on the engine block, then the evidence would indicate that the engine block is not original to the car.

I think the only significant difference is in the oil filter mounting pad. Does your car have the XK140 oil filter or the XK150 oil filter? Do you have a photo of it?

(Mike Spoelker) #3

Maybe this will help. (Photo credit to Rob Reilly, retrieved from the Jag Lovers photo archives) The attached photo is of an XK140 block. There are 4 peripheral holes for the mounting bolts, three large holes and one small hole. The three large holes are the supply to the oil filter from the oil pump (rear hole), return to the main oil galley from the oil filter (top hole) and the excess pressure bypass (front hole). The small hole connects the main oil galley to the center main bearing and is either plugged or blanked off by the filter housing. Early engines (XK120, 140, et al) had an internal excess pressure bypass, so excess pressure was simply dumped/sprayed back into the sump and on the spinning crankshaft via the front hole. There are several reasons why this is not a good idea, and the practice was soon abandoned and replaced with an external bypass that dumped into the sump via an external hose or tube below the normal oil level. I believe the XK150 falls into the later category. As a result, I believe you will find that XK150 and later blocks either lack the hole for the internal bypass for the earlier filter or are equipped with a blanking plate.


(Mike Spoelker) #4

A later block, circa 1964 without the bypass port.

(Rob Reilly) #5

Block serial number prefix V is very definitely from an XK150. Head serial number prefix G is very definitely XK140. The head and block serial numbers always matched from the factory.
However, block casting number C8610 FF is correct for XK140 and 3.4 XK150. I have one of each, G4686 and V5144, both with casting number C8610 FF. Both do not have that plug in the small filter port as pointed out by Mike. Although the V block could have lost its plug if it once had one.
The XK150 parts book gives C15951 as the part number of the 3.4 cylinder block, with C15867 Plug for Oil Filter Flange.
Is that plug the only difference between a C8610 and a C15951? Did they not bother to change the number in the foundry mold? Possibly.
The sump and oil filter assembly are very different for 140 vs 150.
For you, we probably need to investigate whether you have mismatched parts, which has been a problem for others blessed with cars coming from ignorant mechanics or restorers.
Can you post pix of your sump and filter?

(Roger Payne) #6


The numbers tell you most of the story.
Your original Engine G3662-8S would have had a C.8610 block which was used up until XK140 Engine Number G4430 (don’t worry about the suffix -8S which denotes 8:1 cr pistons only, can be also -7 or -9).
From XK140 Engine Number G4431 to the last at G9980, and from the first 3.4 XK150 Engine Numbers V1001 to V6860; a slightly revised block C.8610/1 was now used. Your block, stamped V5057-8 is most definitely a C.8610/1 block as was originally installed in a 3.4 litre XK150.

Now as noted by others, although an XK150 application C8610/1 block is identical to and interchangeable with a later XK140 application C.8610/1 block (other than the physical stamped in Engine Number), you do need to be careful and check all the associated parts bolted on. The Oil Filter and the Sump are the two main areas you need to have correct. Also you should be aware that a C8610/1 block is totally interchangeable - as a short-motor assembly - with your XK140s original C8610 block, the only difference being in the timing-chain tensioner arrangement, and thus associated drillings in the block casting to suit - so a minor change and not a major change, thus only the C8610 to C8610/1 progression, and not a totally new part number.

But your specific question. No your V5057-7 block is NOT the original to your XK140, but with attention to bolt-on detail, is totally useable/interchangeable. As noted the XK150 application uses an external oil-return hose from the revised oil-filter, quite different from the XK140s internal oil-return arrangement - thus an XK150 plugs the internal oil-return port, has a different sump with an external return pipe inlet, has a different oil filter assembly with an external oil return exit, and a rubber-hose. So that all works OK in an XK140, but visibly quite ‘non-authentic’. If you want to make it ‘look authentic’ you need to source an XK140 Oil Filter (there are three variations) and an XK140 Sump (there are two variations), and remove the oil-return plug in your C8610/1 block. If you really want to get XK140 back to ‘authentic’ then you need to source a correct C8610 block, and then make a decision as to ‘changing’ its stamped in Engine Number to be G3662-8S or not, given hardly worth the effort/fraud as its near impossible to see/read in an installed engine.

See below pic - this is the blocks oil filter interface on another XK150 C8610/1 block - number V6460-8. Note the oil-return plug has been removed, thus now XK140 application/filter suitable.


(Mike Loper) #7

Thanks gents…I appreciate your thoughtful responses. I’ll upload three photos to help illustrate what I have. So, we’ve definitely established that I have an XK150 block attached to the original “C” type head. I believe I have an XK140 pressed steel sump (it is 12.5 liters/13.21 qts.) as shown in the photograph. I don’t know if I have a 140 or a 150 oil filter canister, as I have no XK150 information. Perhaps one of you might shed some light on the filter and bracket. Unfortunately, I do not have any photos of the block showing the oil supply and return ports, but will photograph this area soon when it’s time to change the oil. What happened was: I had every intention of overhauling the engine myself, but as I was disassembling the engine I realized the original head was cracked so I shipped the entire assy. up to XKs Motorsport in San Luis Obispo, CA. They overhauled the engine while I focused on the frame and body.
If one or more of you could help in this regard I’d certainly appreciate it…

(Mike Loper) #8

After reviewing the information in “XK 140 Explored” by Viart, page 196, it now appears I have an early type XK140 oil filter attached to an XK150 block. In addition, on page 195 of the same book, it looks like I have a late, pressed steel XK140 oil sump. There is no external oil return. If you gents could confirm or deny or make other recommendations, I’d certainly appreciate it. I sometimes have felt as though I’m working by myself in a closet, but having the ability to communicate with others who have more experience is extremely helpful. Thanks.

(Rob Reilly) #9

We’ve discussed oil filters frequently on this forum.
Here’s an example.

You appear to have a standard XK140 filter, with an anomaly.
FA2690 used on early XK140 G1001-G1907 normally would not have the external bypass valve,

which I see yours has.

FA2690/101 used on later XK140 G1908-G6232 is the same but with the bypass valve. So it may be that you have your original filter but the wrong tag.

Here is a 150 filter.

So my recommendation is to find out if that small hole in the block has or does not have the plug as pictured by Mike, and do you have two or three big holes.

Here is block G4686

(Roger Payne) #10

If you care to look at credits of XK140 EXPLORED you will see I was actually co-author, although only shown on front cover as “EDITED BY”. Most of the detailed research work was mine, with Viart doing all the excellent artwork/line drawings that are the immediately apparent feature of this book. The page 196 detail on Oil Filters was the first time this level of detail, and detailed illustrations had ever been published before, but please note, this was done back in 2012, and I have since marked up my master copy of this Plate 4-d1 with a number of refinements, and indeed a couple of minor corrections, the most significant functionality error being the Bolt Head at the top of the lower drawing - the EARLY type FA2690/101 filter - is 3/8"BSF and not the 9/16AF as shown (don’t know how this error escaped correction, as I was well aware of this detail at time, with many XK140s in USA or ex-USA having the bolt butchered down to allow a 9/16AF spanner to fit, with the average USA workshop not having BSF spanners (Same error with the underneath oriented bolt of course with the top drawing) These errors were my fault, as Viart simply did the artwork as per my photos and/or instructions re text and captions.

Most of the other refinements I have marked up are more accurate detail re colours and finish, so not things that matter functionally. The paint colour I now describe as being ‘Dark metallic brown’ which I have now done an exact colour match for my own September XK140 which has its original FA2690/101 oil filter, as should be yours.

See photo below, which shows my FA2690/101 partially restored - the metallic brown paint is 100% accurate. Note the top bolt is still my butchered original that you can now force on a 9/16"AF spanner, that I debated how to best restore, but solved the problem by sourcing a non-butchered original here in Australia where our mechanics were well used of correct 3/8"BSF bolts and associated tools.


Note the metallic brown paint coverage is on the outside of the steel cannister and also all over the cast aluminium head only, and there is no white label/stencil on the canister as there is on later FA2708 oil cleaners (not shown in PLate 4-d1, an omission that I have marked up to correct).

Your correct OIL CLEANER should be this same FA.2690/101 as is mine (and if this matters to you painted the same, with no white stencilled label), and I have to say, it does look to be correct, so maybe your Tecalemit Plaque was not overstamped with the added /101. The plaque for the earliest FA. 2690 and the second FA.2690/101 are identical, with the /101 just added/stamped in, just above where the FA.2690 is printed.

The important detail is that your filter does incorporate the Relief Valve assembly - see page 197 (Plate 4-d2) which it appears to have in photo, thus I suspect your plaque has simply omitted the extra /101 stamping.

The most important thing is for this filter to match your C.8610/1 block whether its original G3662-8S block or your now V5057-8 XK150 block with its blanking plug removed. See the rear face of the correct FA2690/101 filter head below:-

You can now see where the various oil passages are, and what are just depressions in the casting.
What is not always fully appreciated is that you MUST of course use the correct gasket between the Oil Cleaner head, and the oil cleaner mounting platform on the block. There are several different gaskets that all have the same external quadrilateral shape, but the gasket used must align with the specific oil passage holes in the FA2690/101 oil cleaner head and the C.8610/1 block. Yours is not a 1955 original gasket design, but is still functionally correct later design/manufacture exposing/aligning the main oil passages, and sealing the required boundaries.

I mentioned before, there are two different XK140 Sumps. See page 195 (Plate 4-c2) This shows the two different XK140 sumps, and describes/details their minor difference, and also shows an XK150 sump for comparison (showing its added external oil return pipe).

From what I can see from your photos, all looks OK.


(Mike Loper) #11

Fascinating information gents, and much appreciated. I’ll put this information in my restoration archives. There is much to learn about these beautiful cars.
My confusion may have stemmed from the time I originally pulled the engine out of the car. As you can see from the attached photo, the oil cannister and filter assy. were original to me (not the car) when I began the restoration. I incorrectly assumed the assembly was original to the car in the first place. It wasn’t until I finished the restoration that I happened upon “XK140 Explored” and Jag Lovers Forum. Until that time I was relying on several other commercially available books such as the Original Jaguar books and the Service Manual. By the way, I’ll likely paint the oil filter when I remove it to check the mounting platform, although I’m sure the block has been modified as the odometer registered over 73,000 miles when I acquired the car and the last restoration took place in the '80’s.

(Mike Loper) #12

I have had a chance to do some additional research into this subject as recommended by Rob Reilly and Roger Payne back in August of 2018. This past weekend I pulled the oil filter canister and mounting bracket and now have been able to see the oil passages on the block.
I indeed have the same oil passageways as Rob Reilly’s block G4686, as shown in my attached photograph. I also have the same Tecalmit oil filter assembly as shown in Roger Payne’s photograph, including what appears to be the blanked off quadrant in the upper right area of the aluminum filter head. Again, see my photograph for comparison.

Using Mike Spoelker’s description as a guide, along with a visual inspection of my oil filter assembly, I believe I now understand the way in which oil flows through my oil filter and to the engine. Mike states, “The small hole connects the main oil galley to the center main bearing and is either plugged or blanked off by the filter housing. Early engines (XK120, 140, et al) had an internal excess pressure bypass, so excess pressure was simply dumped/sprayed back into the sump and on the spinning crankshaft via the front hole.”
The small port leading back to the center main bearing in my XK150 engine is blanked off by the filter housing. I also have a spring loaded ball check valve (see photo) which, if opened, allows oil from a plugged filter to empty “dirty oil” back into the engine through the center oil passageway.
Here are my questions:

  1. In your opinion, have I correctly described and shown the oil flow through the oil filter and the engine?
  2. Since I have a safety relief valve (1) and a ball check (2) which can continue to provide oil to the engine in the event the oil filter becomes somehow plugged, is it safe to say, in your opinion, my oil filter system is adequate for my XK150 block Even though the small oil passageway is blocked by the oil filter head? I believe it is, but would appreciate your opinion.

(Rob Reilly) #13

Hello again Mike L.

  1. Yes, you have correctly described the flow.
  2. You’re good to go. The port labeled “This Port Blocked” connects directly to the port labeled “Filtered oil returns…” right behind that web of iron you can see between them. In fact, behind all six brass plugs in the side is a long fore-n-aft passage that connects “Filtered oil returns…” to all seven main bearings.
    So you have a completely normal XK140 system with no mismatched parts.

(Mike Loper) #14

Thanks Rob…this is quite a relief to me and is wonderful news. Appreciate your knowledge and willingness to share it. I had no idea there was a connection in the block.