Correct Carburetor numbers for XK140 MC

I am selling a complete engine for an xk140MC on BAT. Someone says they believe I have the wrong carburetors. I am not sure but believe they are correct. Anyway I have three sets of carbs for an xk140,(I think). The set on this engine has the markings - M6 and SJ on the top of the carb and on the side of the body is AUC 6040 X on both carbs. the rear carb has the written number 6044 under the AUC 6040X and the front carb has 6041.

The other set of carbs I have have the same AUC numbers etc but the top flange has the number 7 then L11 and they same written numbers under the AUC as I mentioned above. The other set is on my car and is in a different location.

I think the letter and number after it might be the date of the carb. The engine number on my motor is

Can someone please tell me whether A. Both sets are correct. B. One of the sets is correct, or C. neither set is correct.**

Thank you

My comments are very much ‘provisional’ as you really must supply photos to allow conclusive identification of what SU Carburetters you have; all the markings relate to the main body only, and these SU carburetters can be, and often are a mix and match of various parts; for instance it is commonly seen for a Suction Chamber from one carburetter, being fitted onto the main body of another, that are from different variants of the carburetter.
Having said that, my comments therefore relate to the main bodies only, for which you have provided details …
FIRST SET: With AUC 6040 X on both carburetter bodies, with 6044 and 6041 etched underneath. These are indeed H6 carburetters of the variant suitable for a late XK120 or XK140 or Mark VIIM saloon from early 1954 up to late 1956. The M6 and SJ stamping on one (or both?) confirms be original from a mid 1955 build standard XK140 (not an XK140MC) . So these are not original to your engine G3614-8S being from an XK140MC and built a little earlier in 1955. However, apart from the Needles fitted, and the M6 and SJ stampings, they are otherwise totally correct (bodies) for that engine.

SECOND SET: Same AUC numbers but what about etched numbers?, but if as the First Set same comment applies for a late XK120 or XK140 or Mark VII saloon from early 1954 up to late 1956.
The 7 and L11 stampings however tell you these are ex a Mark VIIM saloon built in late 1954, and not an XK140. But again, apart from the Needles fitted and the 7 and L11 stampings these H6 bodies are otherwise correct for the XK140MC engine.

If I was buying, I would be more concerned about whether they are correct/original H6 twin carburetters, or whether mix and match pair or not, so photos needed…

Hello Folks,
I am happy to hear that one can date carbs by the numbers and letters stamped on the flange. Is there a chart that has the decoding? I have some H6 carbs I’d like to know more about.


Wes Keyes
York, Maine

These SU Date Codes is something I worked out in my own SU Research efforts Wes, and is not something I have ever produced any simple chart of, albeit I have mentioned/detailed in a number of papers I have had published, including in Philip Porters XK Gazette some 10 years ago, but has now been offered on a number of sites…
Essentially with H6 and H8 carburetters, there is always one code-pair, and with later H6 two-codes stamped on the top-edge of the main body flange.
The DATE-CODE is the LETTER-NUMBER stamping, and if there is a second code it is the NEEDLES fitted to the H6 carburetter (when assembled by SU before delivering to Jaguar.)

The DATE CODE simply in the first letter is a code for the year with A = 1945, B = 1946 etc but jumping the letters I, J and O (not used). So relevant to XK120/140 H6 and H8s.
1949 = E
1950 = F
1951 = G
1952 = H
1953 = K
1954 = L
1955 = M
1956 = N
1957 = P
and so on for XK150/ E-type HD6 and HD8, but a few more later letters missed, before restarting at A again…

The NUMBER denotes simply the month, 1 = January, 12 = December

There are a couple of anomalies, but that covers 99% of XK 120 and XK140 carburetters (and also Mark VII and Mark VIIM) Where the Needle Code is stamped in, that tells you whether XK120, XK140, XK140MC, Mark VII or Mark VIIM

Note - this is the DATE that the carburetter was made, so given delivery by SU to Jaguar, then warehousing, and lead time to fit to an engine then lead time for that engine to be fitted to a chassis and lead time for that XK140 to be made, the carburetter date typically dates 2-3 months earlier than the Date-of-Manufacture of the XK120/140/Mark VII/Mark/ VIIM.

Have fun………….

Hi Holden,

How did you get on with selling on BaT?

I have a fully restored semi-race spec Type-C engine I’m trying to sell and was wondering if you reached the right market on BaT?