Continuing the discussion from Very early XK120 engine parts I’ve never seen before:
Wiggles, you raise a most interesting point, but rather than gazump the ‘Very early XK120 engine parts’ thread, time to start a new thread.
You note your parents Silverstone LT-2 had ‘Sandcast’ (H8) carburetters.
LT-2 was a car built up basically as a standard XK120 chassis 660748, but with a lightweight-magnesium body, built alongside LT-1 (660751) and LT-3 (660741), all in April 1951.
My understanding is Jaguar built up these three essentially standard (for April 1951) XK120 chassis but with ‘lightweight’ bodies as a Plan B, if Plan A - having the all-new C-type Jaguar ready for the June 1951 Le Mans race was not ready. As it turned out the first C-types (XKC001, XKC002 and XKC003) were ready in time, but my understanding is with respect to their Engines fitted, they were all stock standard (for June 1951) XK120, with the sole exception of having manual-choke twin-H6 carburetters fitted, and not the usual XK120/Mark VII thermo-choke twin-H6. After the 1951 Le Mans race, Jaguar decided they needed to increase the power of the XK120 engine for the C-type, and although not then called as such, they developed the C-type engine. The main things upgraded/modified for the C-type engine was the first-generation C-type Head, a revised Inlet manifold, and indeed twin ‘sandcast H8’ carburetters now fitted.
The three 1951 Le Mans team cars XKC001, XKC002 and XKC003 were upgraded with the new C-type engine now fitted, and indeed ran in the June 1952 Le Mans race with this now H8 equipped C-type engine.
My research into H8 carburetters clearly identifies Jaguar working with SU to develop the H8 carburetter specifically for the June 1952 Le Mans race, albeit prototype/experimental work would have started sometime after June 1951, but certainly before June 1952, and my best guess is April/May 1952 as the first working/functional XK engine with H8 fitted.
The first public/race apperance of a C-type after the June 1951 LeMans was at the 15 September 1951 Tourist Trophy race, and although I cannot be positive, most improbable to yet have the new C-type engine fitted, although possible, but if so, these are post-new car modifications.
The fourth car built - XKC004, that was sold privately, was dispatched from factory in May 1952, and again I cannot be sure, most likely had the new C-type engine with H8 carbs fitted, thus if so, was the first Jaguar to be factory fitted with H8 from new.
Now it is most probable that LT-2 (and LT-3), both sold-off/dispatched in August 1951, would have still had their standard XK120 engines fitted, with H6 carburetters (and not H8), but maybe manual-choke ones also as originally fitted to XKC001/002/003.
After Le Mans 1952, Jaguar did offer/list an upgrade package of C-type Head/revised Inlet Manifold and twin sandcast H8 carburetters, but prevailing evidence is these scarce ‘competition shop’ upgrade kits were only available/offered to selected racing teams wanting more performance out of their XK120s.
So given your recollection of LT-2 having ‘sandcast’ H8 carburetters, and I have a photo of LT-2 under restoration with H8 carburetters, it is most probable that LT-2 was the recipient of one of these ‘upgrade kits’.
The actual H8 carburetters are dateable to month and year made. The earliest H8 carburetters so far dated are April 1952 and these are ‘prototype’ H8 carburetters, with the earliest ‘production’ H8 carburetters being dated May 1952.
I would love any close up photos of the H8 carburetters as now fitted to LT-2 - would certainly help with my better understanding of the origins of the H8 carburetter, but based on evidence to date, I have to believe H8 did not yet exist in 1951 at all, and were first seen in an SU/Jaguar prototype functioning form in April 1952, but may have been first seen in early 1952 when Jaguar was also internally testing their new disc-brakes, and maybe publically in the April 1952 Goodwood race where XKC003 was raced by Moss, or in May 1952 Silverstone race where Stirling Moss won in XKC002, and XKC001 retired while running 2nd.
Does anyone know of any Engine photos of XKC001/002 or 003 at these April/May 1952 race meetings?
