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Jaguar XK120 by Bruce Carnachan


The proto type XK 120 was shown at the October 1948 London Auto Show where it received outstanding praise. Production began in July 1949, and ending in September 1954. The first 240 XK 120's were aluminum bodied, called "alloys" and differ from the later steel bodied cars in several ways. Most notable when viewing an alloy, is the windshield corner pillars mount on a rubber pad that extends up the pillar base. The first few cars also had nearly straight side pillars instead of the curved ones of the later cars. These cars also had different shaped side curtains. Visually, the headlight bodies appear thicker than on steel bodied cars, also, the rear fender has less of a curve at the bottom than the steel fenders. The alloy cars trunk or boot latch system was also different, and the first 60 cars had a hole at the radiator base for a starting crank to engage the front of the crankshaft. Some early cars had red orange oxidation paint in the engine compartment and under fenders, the later alloys as well as early steel bodied cars, had flat black paint in these areas, continuing into early 1952. These cars also had chrome plated top bows, hood and trunk supports, as well as seat frames. For some reason, the passenger grab handle at first came down from under the cowl, was chromed, but later, was fastened to dash panel, not chromed at first, then chrome plated. Production of steel bodied cars began in April, 1950, the last alloy car completed in May, 1950. There were 240 alloy cars, 184 LHD cars and 56 RHD cars. Two chassis during this period, were sent to custom body shops, which explains the sometimes quoted 242 figure for alloy cars. Total production from 1949 to 1954 for the XK 120 was 12,078, with 7,612 roadsters or Open Two Seaters (OTS), 2,678 Fixed Head Coupes (FHC), and 1,755 Drop Head Coupes (DHC). These break down to 6,437 LHD and 1,175 RHD OTS's, 2,484 LHD and 194 RHD FHC's, and 1,471 LHD and 294 RHD DHC's. The chrome plated bolt-on fender mounted side lamps were replaced in October 1952 with welded on housing that incorporated turn signal lights (chassis # 672963 LHD 661025 RHD). Also at this time, demister vents were fitted at base of windscreen. Even though the steel bodied cars replaced the alloy cars. the hood/bonnet. doors, and trunk) boot lid, were still made of aluminum. These cars only weight about 80 pounds more than the alloys due to that cars use of ash wood frame to support the aluminum body. To make the XK 120 more comfortable, "Air Conditioning", that is, a heater, and footwell vents were installed in November 1951 (chassis # 671493 LHD, #660911 RHD), with the air vents about 600 cars earlier (#671097 LHD & 660675 RHD). In December 1952, Trico Windscreen washers fitted, and synthetic enamel paint was used (the original can of touch-up shipped with my 1954 XK 120 smells and thins with lacquer thinner). January 1953, a zipping type top/hood rear view panel fitted (#673396 LHD / #661046 RHD). September 1954, a flat horn push fitted (OTS #675926 LHD / 661172 RHD; FHC, #681481 LHD #669194 RHD; DHC, 678418 LHD / #667280 RHD). Most cars had gloss black painted bumper support irons, but several early cars, particularly those with light color paint, had body color. The welting between the rear fender and body, was always body color, as is the welting behind the license plate mounting on the trunk deck - although I have seen factory photos with this black on some early coupes. From early 1952, all interior panels of the body, except bolt on inner fender liners in the engine compartment, and the plate under the spare tire area which were gloss black, were painted body color while body was off the chassis. Note: this includes the hood hinges and bolts. The small pieces in front of radiator were gloss black. It should be noted that the FHC introduced in March 1951, had the welded on side lamps although a few early ones did use the bolt on chrome ones. Both the FHC and DHC had wood veneer dash panels, with wood trim on door caps and around windows. It is known that a few OTS cars on special order at the request of the purchaser, had wood dash panels. I saw one with the original order, in 1970, in Los Angeles. The wheels of the early cars were disc and painted the body color, as were the recessed area of the hub caps. Beauty rings were optional. Beginning in the Fall of 1951, wire wheels were an option but were standard on the SE Model (SE standing for Special Equipment, which U.S. dealers called the "M" or Modified) The wire wheels were painted either body color, or silver color. Chrome wire wheels became available in mid 1953, and came two ways, all chrome, or just hub and spokes with rim painted aluminum color. (I have only seen pictures of this arrangement) The interior of the OTS had leather seats and center piece, with Rexin (a leatherette like material) covering all other panels except the compartment surround which is leather. On some of the early cars, it seems the dash panel was Rexin covered, but later cars used leather. Carpets were of matching color, some times a different shade if the seat upholstery was of a light color. If the seats were two colors, the carpets usually matched the darker color. The carpet material that covered the inside of the "firewall" had two holes in it where the clutch and brake pedal rods went through. The foot carpets snapped together just under the front of the seat frame, and slid under a chrome piece in side the door opening. They also had a leather scuff piece sewn under the pedals. This pad was the same color as the carpets. The carpets were of the cut-wool type (Wilson). As a special order, the doors and kick-panels could also be covered in leather. This is more common to the DHC's and some FHC's, the former being introduced in April, 1953 and was much more refined with its roll-up windows and padded top that when in the down position rested behind the driving compartment with a fitted cover. The later versions of both the FHC and DHC in the SE specification came with a single exhaust system instead of the normal SE dual (louder) exhaust. They also used a remote air cleaner for the carburetors, mounted in front of the radiator. While on the subject of color of paint, it should be noted that during the mid 1951 to early 1952, there was a shortage of materials for chrome plating, quite a few XK 120 OTS's and FHC's came from the factory with painted tail light housings. What follows are two statements from the Jaguar Color Schemes pamphlet that I obtained in January 1950. "The color schemes listed are standard, and any deviation involving special treatment of coachwork and/or upholstery will entail extra charges for which a quotation will be given at the time of ordering." and "Owing to the fact that carpets carpet bindings and door pipings are supplied in colors to match standard upholstery only, it is strongly recommended that patterns of these items be requested before a final is made on non-standard upholstery In the absence of any instruction to the contrary, non-standard upholstery will be supplied with carpets, carpet bindings and door pipings in a stock of colors nearest or most appropriate to the upholstery chosen." Usually the later cars from 1953 on, had a single color upholstery but the above color scheme list has body colors bronze, birch grey, suede green, black, red, silver, pastel blue metallic, pastel green metallic, and cream. The interior trim listed biscuit and tan, biscuit and red, suede green, biscuit and pigskin, red, light and dark blue, but I have seen an early 1951 car with original two-tone green seats in a black body. The Mark Five DHC and Saloon models, listed in the same Color Scheme list, have many more combinations, 59 for the DHC Mk V and 25 for the Saloon, verses just 12 listed for the XK 120 "Super Sports". In the later years, other colors were added to those available for the XK 120 and the XK 140. It should be noted that the English "Cream" is pale yellow. or primrose, to the Americans. The old English White is what we call cream. The first three production XK 120's were painted red, white (old English) and blue (light) and raced at Silverstone in those colors. Under the hood/bonnet, as mentioned before, was body color from spring of 1952, but flat black before then. Many cars had undercoating installed on the underside of the hood/bonnet. It may have been a dealer option as it was popular in the U.S. for this treatment to new cars, but I believe on the later cars it was applied at the factory, particularly inside the fenders. They never applied under-coat to the "firewall". The radiator tank is gloss black, and the only chrome in the engine compartment is on the acorn nuts on the head bolts and valve covers and the knob for turning on/off the water to the heater (always leave this on, prevents rust and can help cooling). The XK 120 cylinder head, made of aluminum, is of that color or silver. The polished aluminum cam covers never have a "C-Type" plaque on them, even if they have a C-Type head, The plaque was used on the XK 140MC in 1955( even the early 1954 XK 140 MC's did not have them) . The early engines used a cast aluminum five-bladed fan, but in May 1952, from engine #W4383 on, a six-blade fan, aluminum blades riveted to steel hub, was used. In April, 1952 a tandem or dual master cylinder and self adjusting front brakes were used ( 672049 OTS LHD, 660980 OTS RHD, 679622 FHC LHD / 669003 FHC RHD). Brake drums were painted several different colors, most notable were black, silver, grey, and red. The engine block is a dark color, usually black but I have found original colors on two engines to be a very dark green and a dark grey. Black is most common. On the optional "C" head, I have found that dealers would make the modification on the original cylinder head, or install a new C-head from the factory, stamp on the engine number, and in some cases, the factory may have sent a head in 1955 or later that had the "C" cast in the center. Two 1-3/4 inch S.U. carburetors were standard, but optional was a 2 inch version. These were "sandcast" and did not have the smooth polished finish. Also optional was a set of 9 to 1 piston for higher compression. Standard in the U.S. and Canada, were 8 to 1 compression ratio pistons. in England and Australia and some other areas with lower octane gasoline, 7 to 1 pistons were standard. The W or F and four digit engine number will have a dash and 7, 8, or 9 behind it to indicated the compression ratio. A brass plaque with Chassis, Body, Engine, and gearbox numbers stamped on it will be fixed to the "firewall", the right side on cars equipped with the heater, and in center with out the heater. The chassis number is also found on the left side frame top, near the master cylinder and exhaust down pipes. The engine number is found on the right side of the block where the oil filter base bolts on. It is also found at the front of the head, above the first spark plug. The body number is found on a small tag riveted to upper firewall/scuttle on left side. The chassis number can also be found on some models, (early), on the front cross member. The standard exhaust has two down pipes merging into one, that passes through the chassis crossmember, into one single muffler and exits the rear. Early cars up to about the end of 1950, had the tail pipe exit under the left rear fender. Later cars brought it straight back under the trunk on left side. The SE models had two pipes with flex, back under the frame, bolted to a dual Burgess muffler, and two pipes back to the tail. While at this end of the car, note that the rear springs are covered with gaiters, laced, and with two areas fittings. Also the reversing light/license plate light should be pointing straight back, not pointing to the sky. The mounting plate is bent at the top of the license panel. The rear bumperettes have the thick part of the body at the top. These are a left and right pair, each are off-set slightly to clear the trunk/boot lid. This lid should have the rubber seal glued to the lip of the deck lid on later cars (mid-1953-54), leaving the trough in the body open to drain water. The early cars had the rubber seal in the body trough, which allowed rain water into the boot when opened. The steel rod that supports the deck lid and also that used to support the hood/bonnet, were chrome plated on early cars up into 1952, after the Spring of 1952, these were painted grey or beige to match the seat frames and top bows, and black in the engine compartment. The seat frames and top bows of the early cars were chrome plated, The top had a fixed small back window, with the 1949 and into 1951, having a shorter back of the top. the later cars extended the chrome hold-down clips for the rear of the top, to 12 inches back from the edge of the driving compartment. An interim back-window opening was used in 1952, where the back-window canvas zipped open from side to side across the top. and laying down on the rear deck area inside. As the rear window had four rubber grommets so it would not rub the chrome metal frame on the body or on the battery box cover when folded away, the class on early cars, and plexi-glass on later models would not be scratched. However, at speed, the wind would lift the back panel, so in 1953, the top that zips up both sides, and across the bottom, using three zippers, then swinging up to snap onto two Dot fasteners on the second from rear top bow was adopted. This is by far, the best arrangement and was used on the XK 140 OTS as well. The area behind the seats, where the two six volt batteries are housed under a cover held with two Dzu fasteners, was covered with a thin material identical to that used as book binding. The FHC and DHC had a different treatment than the OTS, which had its top stowed behind the seats. This is why the OTS has a cut-out in the back of the seats that does not appear on the FHC and DHC. The FHC had a shallow storage space over the battery box, with the top a few inches below the rear window. The DHC was similar but with more space for the zip open back window to lay in. Mote that it did not snap up like the OTS top, due to the padded and lined interior. There were three types of seat backs available in the OTS, and two in the FHC and DHC. Most came with a semi-curved or "bucket" style, although a flat back could be ordered and often came in the FHC and DHC models. A racing style bucket seat could be ordered, it was the same as used in the C-Type. The early Special Equipment models came with small racing windscreens, as well as wire wheels, dual exhaust, lighter flywheel, stiffer torsion bars and springs, crankshaft dampener (later standard from #W8381, also lightened flywheel from #W8275 in May, 1953), but the racing screens became an option in September 1953. The dual exhaust, a straight through type, is a useful option, often supplied by dealers to standard XK 120's, that gave about 10 horsepower more than the single exhaust models. The OTS XK 120's had two AC aircleaners from December, 1950, painted black. As the FHC and DHC used a remote aircleaner located in front of the radiator, they used flexible rubber hoses to the carburetors. The hose clamps found on the XK 120 are British made Jubilee type for the large water hoses, however, you may find U.S. made screw clamps on the smaller pipe fittings. Remember, Jaguar, along with other small British car manufactures, took advantage of the large supply of surplus WW II U.S. Air Corps supplies, particularly hose clamps. The U.S. airplanes used many small hose clamps, which had to be changed each 100 hour check. In mentioning this strange finding of American clamps on British cars with members of the Riley Car Club, the Morgan Car Club, a Jowett Jupiter owner, and an Austin A-90 owner, they all have found original small U.S. made clamps. My M.G. never had these clamps, only the large wire type, as it had no heater hoses or a pressurized radiator. (to give an idea of the size of the U.S. 8th Air Force, operating out of England during WW-II, I recently talked with a ground crew veteran who stated his Air Service group had 30,000 men. Ours in China had about 700 to 800!) With total XK 120 production averaging about 195 per month, over its 62 month run, Jaguar was quite the small company. I believe the first full year of the 1954 Corvette, that year along exceeded production of the five years of the XK 120. One final note on the carburetors of the early XK 120's, the 1949 and into the 1950's, had a taller piston-dampener housing and lacked the aircleaners. Many of these early cars had the aircleaners installed to prevent large particles of dirt entering the carburetor. Also, a different type front motor mount was used on the early cars. (I have an engine in the W1200 series that has this front mount). Tires fitted to the XK 120's 16 inch wheels, either disc or wire, were 600 X 16", usually Dunlop Roadspeeds. Competition types could be fitted, and some may have 6.50 X 16" as the C-Types used. The Michelin X Radial tire was produced from 1948 and could be found in the 600 X 16" size, while Pirelli introduced their radial tire in 1951 as a 185 X 16", using the metric system. These 185 X 16's have a slightly smaller diameter,, giving about one MPH less speed per 1,000 RPM engine speed. There are some 185 X 16" radials available now from Specialty Tire shops, Michelin has one suitable for racing, and Firestone of Australia has one, being a "S" rated for speed. There are several sources of bias ply 600 X 16" tires; both in black wall (Avon Turbo speed is a good one, and white wall, the latter I believe are Firestones, or Lester 's. This is a problem facing car owners with high performance cars that use narrow 16" wheels, not just Jaguars, but Aston Martins and some Ferraris, although they often had wider rims. The Avon Turbo speed, black wall only, is speed rated to 130MPH with a full load of 1250 pounds per tire. That is about 1,000 pounds more than an XK 120 OTS weighs. For after market replacement of batteries, there are some six volt batteries about the same size as the original Lucas, but you may have to look hard to find ones the battery covers will fit. I believe Interstate has one. There are several suppliers of very good reproduction leather seat kits and carpets, also the rear spring-gaiters have been reproduced. A hard item to rechrome are the out side windshield posts, these are aluminum while the center one is bronze. Reproduction posts made of brass and chrome plated maybe the best way to go as rechroming the alloy ones often produces pits. (these were never polished aluminum as some owners claim!) One thing must be stressed on the XK 120. During its over five year production, there were many changes, noted Jaguar authorities such as Andrew Whyte and Paul Skilleter, estimate nearly 1,300 fairly major items. You would not say "no two are alike" but you could certainly notice the difference between a 1950 model and a 1954 version. Two more comments on originality, some early cars had white steering wheels instead of black. And the early engines did not have the front studs on the camshaft covers. There was a factory dealer installed modification that consisted of tapping a hole for a stud in the head between the highest point of the cam covers and bolting a hold down over them. A later factory change was a machine screw counter sunk in the high part of the cam cover. This gave way to the three studs on each side, but no date is listed. Viewing June 1951 pictures of the engine of the C-Types on the way to Le Mans, shows no studs, and personal inspection of an early 1951 FHC, the 195th made, showed no studs. This car also had the chrome hood stick and seat frames. Also, the passenger "grab" bar on early cars was painted instead of chrome, this probably only extends into mid 1950. Due to the shipping delays from the time a finished XK 120 left the factory until it arrived at a dealer in the U.S., a car completed in, say September, 1950, may not have sold until 1951. The DMV of California, like most states, labeled the car as a "year model" when first sold. The best source for when the car was made is to send to the JCNA the car's chassis number an they can supply shipping date, color, and distributor-dealer.
Bruce Carnachan
XK 120 Registrar & Membership
Classic Jaguar Association
1754 Hillcrest Ave.
Glendale, Calif. 91202

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