[pre-xk] Engine Numbers

Occasionally a question arises about identifying a Jaguar engine, so I put
together this list. I still lack info on a few models where I have indicated
by a ? question mark. Perhaps others will let me know the numbers for those
last few, or let me know if I have missed any or stated anything incorrectly.
I am sending separate postings to several Jaguar lists, so please do not
simply reply on those lists, instead send all replies directly to me.
The initial letter or letters of a Jaguar engine serial number indicate what
model car the engine was made for.

For sidevalve engines the number may have been taken directly from the series
used by the Standard Motor Co., which supplied these engines. I do not know
where the number is located on these engines.

Early 2-1/2 Liter pushrod engines also appear to have a Standard number. Is
this because they did not have the Weslake modified head?

The number for the pushrod engines is found stamped on a machined boss on the
right hand side of the block near the rear above the drain petcock; there is
no serial number on the pushrod head. Pre-war engine blocks had the SS hexagon
logo cast into the block on the right hand side; post-war this was changed to
a Jaguar logo.

The number of the XK engine block is stamped on the horizontal shelf above the
oil filter, or for later models on the left on the bell housing flange; on the
head it is on the vertical face in front of the front spark plug. If there is
no number on an earlier head it is probably a replacement head obtained
through the Jaguar Spares Department. Was the practice of numbering heads
discontinued at some point? Following the initial letter(s) there are
generally four numbers followed by /7 or /8 or /9, which indicates the
compression ratio.

The number of the V-12 engine block is stamped in the Vee between the heads at
the rear. There is no serial number on the heads.

In the following list the format is the initial letters followed by xxxx
indicating three or four or five numerals for the sequential numbering.

sidevalve engines
? SS-I
248xxx SS-90
249xxx SS-90
? 1-1/2 Liter SS Jaguar saloon & DHC

OHV pushrod engines
249xxx 2-1/2 Liter SS-100
250xxx 2-1/2 Liter SS-100
251xxx 2-1/2 Liter SS-100
252xxx 2-1/2 Liter SS-100
253xxx 2-1/2 Liter SS-100
LxxxxE 2-1/2 Liter SS-100
MxxxxE 3-1/2 Liter SS-100
? 1-1/2 Liter SS Jaguar saloon & DHC
? 2-1/2 Liter SS-Jaguar saloon & DHC
? 3-1/2 Liter SS-Jaguar saloon & DHC
KBxxxxE 1-1/2 Liter “Mark IV”
Pxxxx 2-1/2 Liter “Mark IV”
Sxxxx 3-1/2 Liter “Mark IV” RHD
SLxxxx 3-1/2 Liter “Mark IV” LHD
Hxxxx 2.5 Liter Mark V
Txxxx 3.5 Liter Mark V early
Zxxxx 3.5 Liter Mark V late

DOHC XK engines
Wxxxx XK-120 early
Fxxxx XK-120 late
Axxxx Mark VII
Bxxxx Mark VII
Dxxxx Mark VII
Exxxx C-type, D-type
Gxxxx XK-140
Nxxxx Mark VII & Mark VIII
NAxxxx Mark VIII
NCxxxx Mark IX
NExxxx Mark IX
ZAxxxx Mark X
Vxxxx XK-150 3.4 Liter
VSxxxx XK-150S 3.4 Liter
VAxxxx XK-150 3.8 Liter
VASxxxx XK-150S 3.8 Liter, E-type 3.8 Liter
BBxxxx 2.4 Liter Mark 1
BCxxxx 2.4 Liter Mark 1
BDxxxx 2.4 Liter Mark 1
BExxxx 2.4 Liter Mark 1
BGxxxx 2.4 Liter Mark 2
BHxxxx 2.4 Liter Mark 2
BJxxxx 2.4 Liter Mark 2
KExxxx 3.4 Liter Mark 1
KFxxxx 3.4 Liter Mark 1
KGxxxx 3.4 Liter Mark 2
KHxxxx 3.4 Liter Mark 2
KJxxxx 3.4 Liter Mark 2
LAxxxx 3.8 Liter Mark 2
LBxxxx 3.8 Liter Mark 2
LCxxxx 3.8 Liter Mark 2
LDxxxx 3.8 Liter Mark 2
LExxxx 3.8 Liter Mark 2
Rxxxx 3.8 Liter E-type
RAxxxx 3.8 LIter E-type
ZAxxxx 3.8 LIter Mark 10
ZBxxxx 3.8 Liter Mark 10
ZDxxxx 4.2 Liter Mark 10, 420 G
7Bxxxx 3.4 & 3.8 S-type
7Jxxxx 340, 240 saloons
7Exxxx 4.2 Liter E-type
7Fxxxx 420
7Lxxxx 2.8 Liter XJ6
7Lxxxx 4.2 Liter XJ6
? DS420 Limosine

SOHC V-12 engines
? 5.3 Liter E-type
7Pxxxxx before 7P25000 5.3 Liter XJ12 w/carburetters
7Pxxxxx after 7P25000 5.3 Liter XJ12 w/fuel injection
? 5.3 Liter XJS

AJ-6 engines
? 3.6 Liter XJS
? 4.0 Liter XJS
? 2.9 Liter XJ40 style XJ6
? 3.2 Liter XJ40 style XJ6
? 3.6 Liter XJ40 style XJ6
? 4.0 Liter XJ40 style XJ6

AJ-? 6 cyl engine
? 3.2 Liter X300 style XJ6
? 4.0 Liter X300 style XJ6

V-8 engines
? XK8
? XJ8
? XJR8

Please send additions and corrections to: