A Jaguar XK150S Redesigned to Tackle the Open Road

Photography Credit: Tim Suddard

Let’s say you want to build a bulletproof classic Jaguar, one that will haul you and a companion swiftly, safely and comfortably on long rallies and tours anywhere in the world. It’s certainly a reasonable goal.

You start with a solid 1957 Jaguar XK 150S fixed head coupe. You then renew or upgrade every mechanical and electrical component, throw in some trick NASCAR parts, add a select few Aston Martin bits, build a potent engine and install a transmission designed to survive duty in New York taxis. Finally you tune, test, refine and finish the entire car to a dazzling degree—all the while making sure it looks like, well, your ordinary Jag. 

Then you get in, fire it up and drive the hell out of it for long distances.

That’s what Jaime I. Del Valle did when he built a car for his wife, Aida. Of course, it helped that he owns a Jaguar dealership and a couple of specialty car shops. 

This globe-trotting couple divides their time between Miami and San Juan, where Jaime owns Jaguar of Puerto Rico. He also owns specialty shops Kat Kare in San Juan and Kat Kare Motorworks in Miami. All of Jaime’s shops contributed to the complete build of this car, which serves as an eye-catching rolling advertisement for these businesses—and a mighty quick one at that.

Route Book

Jaime is a diehard Jaguar enthusiast. In fact, enthusiast isn’t a strong enough word—he’s obsessed. This man’s 35-car collection is nearly all Jags. So when Jaime came across this Cotswold Blue XK150 languishing in Houston 14 years ago, it’s no surprise that he snatched it up.

“I wanted this one for its color,” Jaime says. “I love the blue.” He also favors this model since it’s four inches wider, and thus a little more civilized and comfortable, than the earlier XK models. The 150S also offers rack-and-pinion steering, four-wheel disc brakes, windup windows and a one-piece windshield. 

He says he wanted a fixed head model because it’s quieter, stiffer and more weather-tight than the open-top versions. This particular example was solid, undamaged and offered the perfect platform—including a traffic-friendly automatic transmission—for Jaime and Aida’s ambitious plans.

His team started by removing the body from the frame, crack-testing the various components and strengthening the entire chassis with seam welding. Then they started the long rebuild, following a comprehensive plan that called for components from the Jaguar family whenever possible. This included parts from later models, as well as safety and competition upgrades. 

One of the more creative parts of the build can be found behind the engine. “I got with John’s Cars in Dallas,” Jaime says, “and I told them what I was running and what we wanted the car to do. They suggested a GM T700 automatic built to New York taxi specifications, because it was virtually bulletproof.” 

John’s Cars built the exact transmission Jaime wanted. The four-speed automatic features an aluminum case, oil cooler and balanced internals. To keep things stealthy, the GM box is controlled by the Jaguar’s stock gear selector system. A lever jutting from the center of the dash tells the transmission what to do.

This four-speed transmission not only snaps solid shifts, but its 0.84:1 top gear makes for relaxed high-speed cruising—about 2800 rpm at 80 mph. The Jag’s rear end also hides some secrets, as the stock-appearing aluminum case conceals an Aston Martin DB7 limited-slip differential and 3.54:1 final drive.

The modernization also included a fresh electrical system, a conversion to negative ground and the installation of a 130-amp, one-wire alternator. Jaime went with the late-model alternator since it’s readily available from any parts store, reducing potential downtime on the road. The ignition is powered by a compact Vertex magneto that houses an internal coil and generates its own current independent of battery power.

Highway Master

During the past year, the Del Valles have covered 15,000 nearly trouble-free miles in the Jaguar. It ran a Jaguar Club of North America track day at Lime Rock, barnstormed through Maine with Brian Redman, and then headed south to Miami by way of New York and Washington, D.C. After a brief rest in Miami, the Jaguar motored north to Asheville, North Carolina, and then ran a leg of the Great Race near Chattanooga before returning back to South Florida. The Del Valles also squeezed in two concours events, one in Connecticut and an AACA National in Melbourne, Florida. 

The couple reports only one small electrical problem that was fixed on the road. The Jaguar narrowly avoided a brush with disaster when an unnamed copilot filled its fuel tank with diesel. “He is still alive,” Jaime says with a shrug, “and I can now safely say he knows the difference between gas and diesel pumps in the U.S.” 

Overall, the couple says they are delighted with the Jaguar’s performance along with the attention it garners. More road trips are planned for the near future, including participation in the Texas 1000. To make these long trips more comfortable, Jaime is busy designing an air-conditioning system that can be installed without modifying any of the car’s original features. 

Arrive in Style

Anytime this Jag is fired up, the music from the custom headers and oversized exhaust draws a crowd. Jaime reports that the quicker steering and brakes work as planned, making the car a stable and safe high-speed tourer. 

“I never used to like an automatic,” he says, “but this four-speed automatic makes this car enjoyable to drive.” He also said the Jaguar has the legs to run with the big Ferraris and Porsches—much to the surprise of their drivers. According to Jaime, this little bonus feature makes those evening cocktail receptions just a bit more enjoyable.

We had the opportunity to sample the Jaguar, and Publisher Tim Suddard came away most impressed. “This car drives like a dream,” he said. “While it seems a bit stiffly sprung for rally work, the ride is not overly harsh and the chassis is controllable in the corners. The quicker steering rack provides crisp turn-in, even when pushed. The engine makes plenty of power, and the automatic shifts smoothly and tightly.”

Do the modifications and late-model hardware sour the experience? Hardly, he says. “And despite its modifications, this is still very much a classic British ride. When I look out over that wooden dash with its gleaming instruments and down that long, flowing hood, it’s hard for me to focus on the highway. I want to keep looking around and soaking up the experience.” 

In the late 1950s, owning an XK150 was said to be the ultimate motoring fashion statement. The machine offered style, speed, stopping power and comfort in an affordable package. 

Aida and Jaime’s Jaguar carefully preserves that tradition while elevating those same features to a level far beyond what the chaps at Coventry envisioned. So here’s a friendly warning: If you’re motoring along a scenic highway, somewhere north of the posted limit, and happen to see a Cotswold Blue XK150 coming up fast in your mirrors, just smile and let it go. This one only looks like your ordinary Jag.

Photography Credit: Tim Suddard

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wspohn Dork
12/22/20 11:44 a.m.

I owned an XK150 S fixed head for awhile - very nice touring cars. That one loosk very nice in what I would call Wedgewood Blue.  They made the 150s with an optional automatic (pretty rare) but it was the BW type 35 which had many shortcomings. I'm sure the modern automatic makes a huge difference.

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