Jaguar V-12 user guide
Performance Builder’s Guide:
Jaguar E-Type Series III V-12
BY MA RK J . Mc COU R T
PHOTOG R AP HY C OUR TE SY S T EW J ONES REST OR ATIONS A ND T R AC K TI ME P HO TO S
opular wisdom states that of all
the E-Type variants built between
P
lighter, triple-carbureted straight-six cars
make the best racers; the V-12-powered ETypes built between 1971 and 1974 were
too plush, too heavy, too complex. While
the Series III cars, both Open Two Seaters
(OTS) and 2+2 Fixed Head Coupes (FHC),
may have been larger and less agile than
their short-wheelbase predecessors, their
12-cylinder engines featured impressive
engineering and a torquey, smooth power
delivery, and they still wore aerodynamic
bodywork considered by some to be the
most beautiful of the era. Although the
steel-roofed FHCs are a natural choice for
high-speed race cars, OTSs perform admirably with judicious body reinforcements,
and both are virtually guaranteed to be the
prettiest cars on the track.
5,343cc, single overhead-cam 60-degree
1961 and 1974, the first series of
The design of this company’s road-going
V-12 was influenced by the 4,994cc V-12
in 1966’s stillborn XJ13 Le Mans racer.
This aluminum-bodied car’s mid-placed
engine had an 86.87 x 69.85mm bore and
stroke, and its Brico pistons and Dykes
piston rings were moved in their castiron dry cylinder liners by a nitrited steel
seven-main-bearing crankshaft and forged,
polished connecting rods. Dual overhead
cams actuated the valves, and dry sump
lubrication and mechanical Lucas fuel
injection circulated the fluids. The final
results of the XJ13 engine’s tuning were
502hp at 7,600 rpm and 386-lbs.ft. of
torque at 6,300 rpm.
Using lessons learned from the XJ13
engine, Jaguar developed the Series III EType’s V-12 to maintain their customary
level of power in the face of ever-stiffer
emissions regulations. Smooth and balanced, the aluminum block and head V-12
featured a number of performance-biased
components, including high-flow, flat-top
combustion chambers with optimally situated inlet and exhaust valves, seven main
bearings and replaceable, cylinder-cooling, cast-iron wet-sleeve cylinder liners.
This engine would gain fuel injection and
be redesigned twice before V-12 production ceased in 1996, the first time in 1981
when it became the H(igh) E(fficiency) with
a redesigned “swirl” combustion chamber
design, and the second time in 1994 when
the HE was stroked to 6.0 liters of displacement.
Considered by many to be overbuilt,
the Jaguar V-12 can withstand significant
cylinder boring, notably raised compression and is adaptable to numerous fuel
delivery solutions. Although Jaguar may
have intended their often air-conditioned,
power-assisted Series III cars to be Grand
Tourers, as opposed to the pure sports cars
of the first E-Type iteration, there are some
enthusiasts who feel otherwise. Stew Jones,
president of Stew Jones Restorations in
HEMMINGS SPORTS & EXO TIC CAR
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october 2007 hemmings.com
•
SELECT COMPONENT PRICES
Engine
Rob Beere Racing Fast Road
V-12 cylinder head and camshaft kit ........................................................... $4,938 (£2,400)
Rob Beere V-12 block conversion for 96mm liners ...........................................
Hayward & Scott stainless steel exhaust system .......................................
SNG Barratt V-12 ignition conversion ......................................................
Drivetrain
Medatronics JT5 5-Speed kit, inc. Borg Warner T5 gearbox,
shifter, new driveshaft, clutch disc and hydraulics,
hardware and bellhousing ..........................................................................................$4,700
Suspension
SNG Barratt uprated torsion bars, pair ............................................................. $760 (£371)
Koni adjustable shock absorbers ................................................................
Safety
Kirkey Intermediate Road Race seat ..............................................................................$725
Simpson five-point pull-down racing harness ...............................................................
$850 (£415)
$1,208 (£587.50)
$594.70 (£289.05)
$129 (£63) each
$105
SPECIFICATIONS
Engine: 7.3-liter, 450-cubic-inch
V-12, alloy block and
head, six 44mm Weber
IDF carburetors, 11.6:1
compression ratio
Horsepower: 600 @ 6,043 rpm
Torque: 578-lbs.ft. @ 3,922 rpm
Gearbox: Five-speed Getrag 265
Ratios 1st: 3.822:1
2nd: 2.200:1
3rd: 1.398:1
4th: 1.000:1
5th: 0.813:1
Racer Resumé:
believe the E-Type Jaguar is the most
beautiful car ever made. I bought my
“I
first E-Type, a 1972 V-12 roadster, in 1985,
and I had no intention of doing anything
to it. I joined the Jaguar Club [of North
America], and a few years later, they started
a slalom program. I started driving in that
program, and began thinking about SCCA
events. Stew was maintaining my original
car, and we decided that it would be fun
to have a car that would do really well in
these events. I didn’t want to further modify
my near-stock car, so we started with a 1973
roadster to make The Beast.
“This car is clearly pretty potent on the
track, and Stew’s wife, Karen, has turned the
best time ever in a Jag, beating the previous best time by a half-second. Bob Hebert
drives for Donovan [Motorcar Service in
Lenox, Massachusetts], and he’s turned a
DIMENSIONS
Length: 180 inches
Width: 68 inches
Height: 48 inches
Wheelbase: 105 inches
Curb weight: 2,760 pounds with roll
hoops and full fuel tank,
50/50 weight distribution
58-second lap in The Beast at Lime Rock. He
comes back with good feedback for Stew…
tweak the torsion bars, lower the tire pressure… and as long as Karen’s autocrossing
it, Stew trucks it around for me. I can’t turn
those times at Lime Rock, so it’s great to
see what the car is able to do at the hands
of a good driver. I’ve hired Bob Hebert as
a coach, and I’m planning to continue to
do more track driving and probably get my
competition license.”
– By Jim Roberge
hemmings.com october 2007 • HEMMINGS SPORT S & EXOTIC CAR
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