Studless Cylinder Head

A bit of a mystery to me, so I would be interested in any comments. I've
recently acquired a very original, low mileage 1951 Mark 7, with early
"studless" cam-cover engine (no studs at front of cam-covers), correct and
original "A" prefix engine number, matching block and i.d. plate. So far,
nothing unusual! However it is in fact an original first type head C.2242,
that I had thought was unique to earliest XK120, with the later C.2242/1
head being introduced before Mark 7 production started. The XK120 Parts
Catalog and the Mark 7 Parts Catalog are quite specific about engine
numbers relating to specific head variations, and supposedly for Mark 7
from engine A.1001 head C.2242/1 was used. The engine is as nice an
original motor you could hope for, still with full nickel plating on
carburettor dash-pot damper screws, all original hoses and TEX clamps, and
even with the surity of its matching numbers, there is no sign of either
the head or even the cam-covers ever being disturbed. So, how did a Mark 7
get an original C.2242 head on it, or is this not uncommon with those more
familiar with Mark 7 detail than I am? - Roger Payne

Roger,  I cannot help precisely with your query, but can maybe date the
manufacture of your head if you give me the numbers from the back of the
head e.g. AC 123 or whatever.  Also, is it a Mills or WYF head?  You will
need a mirror to check. Sounds like a nice car all right. - Regards, John
Elmgreen

Hi Roger Payne & all -- It's entirely possible that some early VIIs had the
studless head installed; after all, they were hand-built, and available
parts on that day were installed on all of the earlier cars -- so if there
were no full-stud heads available that day, a studless head was used to
keep the line running. The definitive check for yours, Roger, would be the
engine # -- on the head at the front between the cams, and on the block on
the flat space inward from the oil filter assembly.  If they match, it was
an original engine and head. Early Mk VIIs had the A-series engine (710003,
the introductory 1950 England/NY show car, had eng. # A1997-7, which almost
certainly would have had studless cam covers; this is the car we've been
citing for Twilight Blue in the recent thread because there's an elegant
photo of it at the NY show).  The INTERNATIONAL Mk VII/VIIM/VIII/IX
REGISTER shows that by mid -'52, Mk VIIs had switched to the B-series
engine, which certainly had fully studded cam covers. In fact, the REGISTER
shows 710005 (5th car from new) with engine # W2161-7; this would have been
an XK120 engine, installed in this particular car -- why -- ???  One more
case for detective work, eh!  I hope all this helps - Larry Martz

Larry, Roger:  I thought it was well accepted that the earliest Mk 7s had
studless heads.  Re the Mk 7 with the 120 engine, most interesting!  Any
other examples?  I have previously calculated that there were about 190
extra XK120 engines made, some used as spares etc etc and one in a Mk 5
(experimental). - Regards, John Elmgreen

Larry, Thanks for comments but my question was not about the existence of
"studless" head, as there is no mystery about A.1001 to A.7026 all listed
as being "studless" heads. My query was about the existence of the first
type of studless head (part # C.2242), as opposed to the expected second
type of "studless" head (part # C.2242/1). The 3rd type of head, part #
C.6733 introduced the extra studs at the fronts of the cam-covers, at
Engine # A.7027 for Mark 7 and W.4691 for XK120. My engine is A.4464-7
which should be a 2nd type head, but is in fact a 1st type, whereas another
really nice engine I have as a garage ornament (beats pictures on the
wall!) A.3553-7 is an earlier engine number, but IS the expected 2nd type
head. Thus my mystery Any Mark 7 owners care to comment - please. - Roger
Payne

John, See my comments to Larry.  As elaborated, there is no confusion over
early Mark 7 engines being "studless", from A.1001 to A.7026, except all
are listed as being part # C.2242/1, whereas my engine A.4464-7 is a first
type C.2242, with spark-plug depression paired for plugs 2/3 and plugs 4/5
and 1 and 6 separate.  Number on back is J842 which is consistent with
engine #. Another engine I have A.3553-7, has 2nd type of studless head
part # C.2242/1 as expected, and number G737 on back, which again is
consistent for Engine # Dead torch battery has delayed me checking casting
brand, will advise later. The "nice" car is quickly being reduced to parts
as lots of goodies interchange correctly to XKs, (and the unique Mark 7
bits are in great condition for Mark 7 owners looking for original/rust
free parts).  A lovely straight/ rust free body shell is free to anyone to
take away, until its final resting place in Canberra tip.  Freight cost is
more than its worth in Australia, however if there is any local, as in
Australian, interest please be quick with your trailer. I am posting this
on the XK lovers list! - Roger Payne

Roger, Pursuant to the objective of restoring my 140FHC as much to its
original condition as feasible, might the MKVII yield include useable
original hoseclamps and, if yes, would you part with them.
Regards - Klaus Nielsen

Roger,  Can you give me the numbers on the back of the valleys of the heads
(e.g. A 123, or AB 123) and also  see whether they are Mills ofr West
Yorkshire castings?   I will then check an correlation with other info. -
Regards, John Elmgreen

Klaus, For your XK140 you are looking for CHENEY brand hose clamps.  My
Mark 7 has generated a set of TEX brand clamps as used by early XK120.
CHENEY clamps are not that hard to pick-up, if you have access to some
parted out Jaguars - Roger Payne

Roger, You will have realised that one of my messages earlier today crossed
with yours.  Question:  why do you say your Mk 7 head is C 2242? I presume
that it is the number cast into the head.  I have also recorded  Mk VII
with A 2963-8 and F 509 (on the rear boss) as C 2242 without the /1.  I
presume from what you say about the other heads that the /1 was cast into
those - can you confirm? I have also recorded XK120 with W 4271-8 as J 794
- this should be a C 2242/1 head also (I did not note the cassting number,
just assumed that was what it was).  Not that early really. I have also
recorded  Mk VII with A 3174-7 and G 714 at the back, again I assumed this
was a /1 head, per parts books without recording the actual number stamped.
However, I would offer the following message from Rob Reilly from Feb 97 as
support for a theory that /1 heads were marked just C 2242 not with the /1
- but maybe you know different - here is what Rob said: 17 Feb 1997 -  On
Saturday I went to see Jim Kakuska at JK Restorations, mostly to show him
my MkV bonnet side panel, but I also asked him about heads. He had examples
of both the earliest and the second studless head. The difference is as
Roger directed my attention to, the seals at the rear of the camshafts. The
first head and cam covers have a groove cut in the middle of the joint face
right at the back, and a half moon rubber (or rope?) seal pushed into them.
The second head has a small gasket or a circular rubber O-ring on the rev
counter cable adaptor (exhaust) and the flanged sealing plug (intake) so
they seal on the back vertical face, and no grooves in the head or cam
covers. Both heads have the number C2242 underneath on the intake side,
there is no "/1" on the second one.  And just to tantalize Roger's passion
for really obscure trivia, Jim told me the very earliest cam covers had the
cutouts for the 8 studs machined too deeply, with the result that they are
frequently cracked from overtightening. - Rob Reilly
I would not mind betting that Bernard Viart has something to say about this
- Brian Pel, any chance you (whose French is so much better than mine)
might be able to have a look at Le Grand Livre for us? - Regards, John
Elmgreen

Hi Roger Payne, John Elmgreen & all -- I think it was you, John, who
wondered about early VII studless heads in the INTERNATIONAL Mk
VII/VIIM/VIII/IX REGISTER -- since Roger noted engine #s A1001 to A7026 as
studless, here's what we show in the REGISTER for early VIIs through A7026
as of today:

RHD --
710003, London/NY show car, twilight blue, A1997-7
710012, to AUSTRALIA, A1040-7
710021, to AUSTRALIA, A1047-7
710053, Simon P. Harris, ENGLAND, A1084-7
710365, Martin Mountford, ENGLAND, A1697-7
710523, Edric Nantes, AUSTRALIA, A1966-7
710525, Robert Platt, SOUTH AFRICA, A1957-7
710608, Urs W. Haenhle, SWITZERLAND, A2804-8
710806, Jorge Misteli, SWITZERLAND, A3044-8
710936, Les and Chris Bradd, AUSTRALIA, A6059-7
711124, Randall Botha, SOUTH AFRICA, A3989-7
711463, John Miller, AUSTRALIA, now scrapped, A1805-7
711464, Kenneth R. Bullis, USA, A4553-7
711645, Andrew Yen, AUSTRALIA, A4848-7
711675, Brian John Smith, AUSTRALIA, A4851-7
711716, Steve and Mary Papworth, NEW ZEALAND, A4922-7
711723, Hans Stammel, AUSTRALIA, A4926-7
711975, Fred Burrow, ENGLAND, A5258-7
712174, John Leuders, AUSTRALIA, A5365-7
712420, (?), AUSTRALIA, A5797-7
712479, Ruchard Jenkins, A5855-7
712485, Steve davies, NEW ZEALAND, A5867-7
712702, Les and Chris Bradd, AUSTRALIA, A6191-7

LHD
730309, Robert Hinshaw, USA, A2055-8
730469, Genevieve Cregar, USA, A2211-8
730596, Robert Sauls, USA, A2330-8
730624, T. D. J. Van Sonderen, HOLLAND, A2351-8
730929, Jerry Parkhill, CANADA, broken for parts, A2497-8
731176, Kenneth Bullis, USA, A2638-8
731233, Martin Mingo Sande, CHILE, A3153-7
731717, Demir Berberoglis, TURKEY, A3723-8
731982, Tyler Ahlgren, USA, A4326-8
732067, P. De Snoo, HOLLAND, A4409-8
732588, Don Taylor, USA, A6709-8
732636, Eeri Immonen, FINLAND, A6740-7
732695, Jeff Ade, USA, A6907-8
732730, Robert Kauffman, USA, A6978-8

Note that most RHD were -7, most LHD were -8.  Interesting research, eh!
Take care - Larry Martz

John, I lifted the body off the chassis on the weekend so its now a lot
easier to have a look underneath the head. As expected, underneath the
inlet side of head are the two raised lettering numbers "C2242", the Jaguar
part No, and "XK774", although the K almost looks like an N, which I
understand? to be the manufacturers casting number.  No numbers under
exhaust side, or anywhere else I've yet picked up, so apart from the usual
"JAG in a circle" quality control stampings on a variety of places, there
may be other minor stampings not yet cleaned properly. The previous
discussion back in Feb 1997, my input was to do with the Cam Covers
themselves, not the heads so I am still unsure exactly where a C2242/1 head
differs from a C2242 head apart from rear camshaft seal recess machining,
although I'm starting to wonder whether I am mistakenly assuming the
pairing of the oval depression around Spark plug holes 2/3 and 4/5, (rather
than the usual single concentric depression) is the key identification
feature. Is there any definitive views yet on visual differences between Wm
Mills and West Yorkshire manufactured heads? - Roger Payne

Roger,  Just one aspect of your message, I thought that the WM heads had
that funny W over M logo thing on them.  Not sure about WY ... or was the
logo the WY?  I haven't checked ... ! - Regards, John Elmgreen

John, The picture I have of my '64 S-type
(http://www.conterra.com/white/xk-lovers/gifs/markings/head-btm.jpg) the
logo looks like a Y over W.  Does this support the theory - early WM, later
WY? - Dick White

John/ Dick, The "Y over W  within an Octagon" logo, I presume denotes "West
Yorkshire" manufacture. A raised cast part number prefixed "WM...",  eg.
WM351  C14958, I presume is "William Mills" part number followed by Jaguar
part number.(C14958 in this instance being a later "B-type" head. My early
studless head, with paired recesses around spark plugs 2/3 and 4/5 has
neither the West Yorkshire Y over W logo, nor the William Mills WM prefix
casting number.  As advised earlier, only identifying marks are raised cast
"C2242" and "XK774" underneath the inlet side. - Roger Payne

If you have any questions or comments send e-mail to: ted@jag-lovers.org
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