Not a Cobra, but a remarkable scratch-built AC Bristol

Car photography by John Webber; Build photography by David Wagner

Carroll Shelby’s Cobra is perhaps the world’s most copied sports car. Sixty years after it first thrilled enthusiasts, countless builders are still having a go at it. 

But respected Cobra restorer David Wagner decided not to build another Cobra. Instead, he chose to replicate, in obsessive detail, an AC Ace, the elegant, British-built roadster that started it all. In fact, he built two.

No doubt about it, this lifelong enthusiast inherited the Ford gene. His great-grandfather, grandfather and father worked for Ford, so he did, too, spending three decades as an engineer. 

He enjoyed some interesting assignments as well. In the early ’80s, tiny England carmaker Autokraft–owner of the remains of AC Cars–was building its Mk4 Cobra, a big-block-styled, alloy-bodied version. David served as the company’s Ford liaison, supplying it with 5.0-liter engines and five-speed transmissions. 

He made many trips to the original AC factory in Thames Ditton, where Autokraft’s Cobras were built. There he spent his free time taking pictures and making notes, learning how these cars were put together from longtime fabricators, who were still using the same tooling and fixtures they’d employed decades before. Autokraft’s partnership with Ford lasted 10 years and resulted in 175 examples of the Mk4 Cobra, most of which came to the U.S.

My relationship with Autokraft was what got me involved with Cobras,” David says. His love for these cars grew over the years, and he started restoring them in his home garage. When he retired, he continued this sideline full time. In the past 30 years, he’s restored about 25 original Cobras from the frame up; he’s repaired, freshened, and built some 75 more, including Kirkham replicas, Autokrafts and AC Bristols. He’s gained a reputation as a restorer who goes to extreme lengths for authenticity. He built a Cobra for Ford CEO Jim Farley and is scheduled to build one for Chairman Bill Ford. 

Today, David owns an original 289 Cobra (which he restored from a basket-case racer), a Kirkham 427, a 1965 Shelby GT350 and one of the Ford-powered Aces featured here. “I often build two or three cars at a time,” he says. “It’s more efficient.” So as you read this, multiply this project’s intricate, time-consuming processes by two. 

Why Not a Bristol?

David was preparing to restore a customer’s very original 1957 AC Bristol when it struck him that these early Aces played a role in the Cobra’s evolution. All the Bristol’s AC bits, big and small, held a wealth of history. 

So he talked to the Bristol’s owner about the possibility of duplicating parts. The enthusiast agreed, and David’s project started to come to life. When he’d stripped the car to its last rivet and cataloged each item, he identified the parts he needed to reproduce. 

Most he duplicated the old-school way, fashioning them by hand, but he went high-tech when he 3D-scanned half the car, its front section. Without access to these AC “templates,” he believes this project never would have happened. 

“Bristols are such pretty cars, simple and clean,” David notes. “I really wanted one.” But the Blue Oval beckoned; he knew he would miss that V8 power. 

“The six-cylinder Bristol engine is a work of art,” he continues. “It’s well balanced, a delight to drive and delivers a unique sound, but I love small-block Fords.” Plus, he realized that Bristols worthy of restoration are highly coveted and chased by collectors. 

So why not build one? David, with a wealth of AC and Cobra experience, a sizeable stash of original Cobra parts (plus parts he’s reproduced for years), bulging files and access to a completely disassembled Ace, told himself, Sure, I can I do what Carroll Shelby did. And I’ll build two.

“I made these cars as close as possible to how I thought Shelby built the first Cobra,” David recalls. He knew, of course, that Shelby didn’t start with a 1957 Bristol, but David liked the vintage appeal of that car’s sculpted front bodywork, which was refined and simplified on later ACs and Cobras. 

And since he’s a guy who loves fast Fords, he opted to add performance upgrades that would have sent Ace engineers into swoons of envy. 

Similar but Different

While a 1957 AC looks much like a 260 or 289 Cobra, a host of parts differ, and David had to determine ways to deal with those differences. For example, a Bristol sits on the same 90-inch wheelbase as an early Cobra, but its track is 3 inches narrower, determined by the length of its transverse springs (which act as upper control arms front and rear) and the length of the lower A-arms on each corner. 

David bought two Kirkham 289 frames and asked the builder to modify their Cobra-like A-arms to compensate for the AC’s narrower track. Kirkham revised the dimensions in its CAD models and then crafted two sets of lower arms from billet aluminum. 

David Wagner didn’t just build one Ford-powered Bristol–he built two. Scans of an original allowed him to create the aluminum bodywork needed for each car. Kirkham Motorsports, known for its Cobra replicas, supplied the chassis.

Other suspension components that required modification included the steering rack tie rods (Shelby used a modified MGB rack) and the rear axle half shafts. David had Eaton Springs build two sets of shorter transverse leaf springs, and he modified steering racks and rear axle half shafts to fit. When these modifications all came together, his faithfully reproduced 1957 Ace bodies would sit on 289 Cobra frames and roll on modified Cobra suspensions. 

When David was restoring the original 1957 Bristol that launched his grand plan, he sent its frame and body to Cobra Performance for specialized bodywork and chassis repairs. “Drew Serb and his guys have all the parts and expertise to build a complete Cobra from scratch,” David says, “and we worked up a plan for my replica project.” 

Using a surface plate, the shop’s technicians repaired and aligned the original AC’s frame, which then served as a template for locating and fabricating fixtures. The fixtures would enable them to weld body-supporting substructures on David’s Kirkham frames. “That required a lot of precise measurement and calculations and was a difficult obstacle to overcome,” David recalls, “but we knew these steps would make things a lot easier down the road.

Crafting Alloy Bodies

For many of us, building a curvy car body from flat sheets of aluminum conjures up a blend of high-tech wizardry and old-world panel beating, and that’s how these bodies took shape. Wisconsin coachbuilder Alan Buresh used scanned data from two Bristols to fashion David’s bodies, because that proved to be the best method to collect accurate data points. 

David furnished the data file for the front section, and another Bristol restorer provided a file for the rear section. Alan fed those files, with their countless location points, into in a stereolithographic printer that “grows” or “prints” a three-dimensional body section in plastic. For the AC, this process required 25 sections. 

Alan reinforced and hand-finished each roughly 2x2-foot section, which then served as shaping dies when positioned in a stretch former against a sheet of aluminum (cut slightly oversize). Hydraulic pressure and stretching, along with expert handwork, slowly forced the soft aluminum into the shape of each die, a process he repeated 25 times. If this sounds like an exacting and repetitive procedure, that’s because it is. 

Next, Alan installed each formed section in its proper position on a body buck, built to the precise shape of an AC body and with vertical support segments every few inches. This device locates and holds sections as they’re shaped and stitched together. Picture an intricate jigsaw puzzle in three dimensions. 

Once properly fitted, the sections were tack-welded together–gas-welding aluminum is an arcane art in itself–and more careful adjustments followed. When Alan was satisfied with the fit, the sections were final-welded into front and rear body clips.

He then applied more gentle shaping with rawhide and nylon mallets, and more finishing and filing and polishing followed. Shaping an alloy body demands a multitude of skills, learned over years. It’s an exacting process that would drive most of us nuts. David says Alan spent about 1200 hours over several months crafting the bodies. “I tried my hand at coachbuilding at Autokraft,” he recalls. “I learned I just didn’t have the patience.” 

Bodies and Frames Get Married

Months passed. When body clips were complete, David loaded them and the frames into his enclosed trailer and pointed his motor home toward California. 

Once there, he spent three weeks working with the Cobra Performance team, fitting bodies to frames. Each frame was mounted on a surface plate, and thanks to the special fixtures built earlier, body-mounting substructures were located on each frame.  

AC and Cobra alloy bodies sit on a network of 30-some sections of ¾-inch steel tubing that’s welded to the frame. While most Cobra tubes fit earlier AC bodies, some are unique and required fabrication. With all the substructures fitted and welded into place, the assemblies were prepped and powder-coated to reduce the possibility of corrosion between the aluminum skin and steel support tubing, a problem on early Cobras. 

“Drew had all the prefabricated Cobra tubing in stock plus the tools and fixtures needed, so this process was relatively straightforward,” David explains. “It’s slow, careful work, but both bodies fit their frames and support tubing without much modification. Without these guys’ expertise, this would have been a mammoth job, impossible for one man.” 

When the front and rear body clips were fitted, their edges were carefully shaped around the support tubing and riveted every 3 inches. The bonnet, doors and trunk lid, which also required tubing support, were crafted and attached separately. 

Final Assembly

Back in his shop, surrounded by shiny Aces on frames and stacks of new parts, David worked on the cars concurrently. “I had these cars sitting side by side,” he says, “and as I completed each step on one, I started it on the other.” 

He fabricated and installed aluminum floor and trunk panels, built and installed fuel tanks, and began final bodywork and paint preparation. Once the cars were painted, he bolted in the rear differentials and suspension components on each corner, upgrading with Wilwood brakes and QA1 adjustable shocks. Slowly, his creations began to look more complete, and soon he had a pair of steering, rolling Aces.  

In the cockpits, he remained as faithful to a 1957 Bristol as possible, handcrafting and trimming dashboards and glove box doors, which differed from a Cobra’s in size and instrument layout. He made new emergency brake handles and pedal boxes. He fabricated Cobra seats and had them trimmed in red leather, fiddling to gain the perfect seating position. 

“If a car is not comfortable, you won’t drive it as much as you should,” he says, “and I built these cars to be driven.” Next came red leather on the doors and carpet throughout. David then installed new windshields, complete with glass, which he ordered from England. 

Finally, he installed the Roush-built, 331-cubic-inch engines, which had been tested and run in on their dynos. He hoisted them into place, along with their Centerforce clutches and Tremec TKO five-speed transmissions. Custom driveshafts finished the drivetrains. 

Like the famed Cobra, David’s creations rely on Ford V8 power. In this case, though, it’s a slightly modernized take: 331-cubic-inch Roush engines backed by Tremec TKO five-speed transmissions.

He hooked up all the systems, added gas and hit the button. “I pumped the gas once and they both started on the first crank,” he says. 

David is a patient, painstaking engineer, accustomed to drawn-out, meticulous restorations, and he claims this 18-month deep dive into Ace building wasn’t that big of a deal. “Honestly,” he says without a hint of brag, “I’ve built so many Cobras I could practically put one together blindfolded.” 

Still, he estimates that he spent 850 hours–that’s per Ace–on final assembly, and that number doesn’t include the time he spent planning, phoning, emailing, coordinating tasks and supplies, dealing with glitches, duplicating and ordering parts, hauling bodies and frames around the country while living in his motor home, or the thousands of fiddly little tasks needed to pull off this project. “Overall,” he says, “it went pretty well.” This man is a master of understatement, too.

However long it took, David has created a pair of masterpieces. As we put this story to bed, we learned that the twin to the Ace featured here has a new owner: Lynn Park, known to the Cobra community as Mr. Cobra. Mr. Cobra has been a Cobra fanatic, collector and restorer for more than 50 years. He’s owned more than 50 and still has a shop full. For David, having his Ace join Lynn Park’s fleet is the ultimate endorsement.

So, What Is It?

Call this a fairly historically accurate take on an evolutionary branch that failed to materialize. It looks like a Cobra–and goes like one, too–but is based on a slightly different mix of automotive DNA.  

So, is this an Ace or a Cobra? It takes an expert to tell, especially if the bonnet is closed. 

What they see is an exact replica of a 1957 AC Bristol, faithful from nose to tail. What they don’t see–although exhaust pipes and brake calipers hint–is that this Ace is powered by a 365-horsepower V8 fed through a five-speed transmission. 

Does it drive like a small-block Cobra? Sure, and some might say better. 

Cobra expert Tom Cotter gave us his take: “David has taken the most replicated car in history and made a spectacular variation of it. It is darned authentic, and he went to such great lengths to find all the obscure pieces he needed–rare AC stuff that Cobra guys don’t look for. Most builders replicate Cobras; he replicates Aces. People in the know will really dig this car.” 

Yes, it’s a replica, but it’s as close to the real thing–with a nod to how the real thing evolved–as most of us will get. In poker, an ace is the highest card in the deck. We were delighted to play a few hands with this one.  

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Flyman615
Flyman615 New Reader
11/24/22 11:18 a.m.

Fabulous project story and accomplishment! Thanks for sharing!

joeymec
joeymec New Reader
11/24/22 11:27 a.m.

I would prefer driving the AC Bristol.  It's closer to the original design.  The Cobras are what they are and much too much power for me.  Plus, you talk to the average person and tell them it is NOT a Cobra.    Raw power is all about getting it to the wheels.  What's the sense of so much power that the car breaks away.  That's just me.  I prefer less power ( but not underpowered) so I can go through the gears without fish tailing on every shift.  Bravo to the Bristol!!

bertbrown
bertbrown
11/24/22 12:27 p.m.

Thanks for the great article about Dave Wagner's Aces.  He told me that it was coming out.

What is not mentioned in the article is the fact Allen Buresh constructed 3 Ace bodies, with the first one going on an original Ace Bristol that is in my garage.  My car had been wrecked at Laguna Seca in 1958 and was in need of a body.   So what to do?  Checking with shops in England meant they wanted me to ship the chassis over there and wait.  I didn't care for that solution.

I worked for an engineering company here in California and we did lots of laser scanning for our clients, so I borrowed our scanner for a weekend and used it to scan an original 2-owner Ace Bristol located not too far from me.  Then working directly with Allen Buresh of Coachsmithing I knew he needed to cover some tooling costs.  So I called old friend Dave Wagner and popped the question, would you like to participate in this endevour and help defer some upfront costs?  Lo and behold, he signed up for 2 bodies!  

That said, Dave works in fine detail, but with lightning speed.  While Dave has been driving his two Aces, mine is just now nearly ready for paint!

Bert Brown

ShawnG
ShawnG MegaDork
11/24/22 12:33 p.m.

Gorgeous car.

I've driven a real 1965 Cobra and I would love to drive an Ace, just for comparison. I bet the Bristol engine is plenty of power for that chassis.

MyMiatas
MyMiatas Reader
11/24/22 12:44 p.m.

When I read that article in my magazine. I was waiting to ask if he built two Aces to offset the cost of just one. Build the two of them and then sell one. But that question I assume was answered. He has both that he drives.  I enjoyed reading about that build and how they came to life.

californiamilleghia
californiamilleghia UltraDork
11/24/22 5:55 p.m.

Is the Bristol motor the same as the early 1950s motor that was based on the Prewar BMW 328 motor ?

bertbrown
bertbrown New Reader
11/24/22 6:45 p.m.

In reply to californiamilleghia :

Yes

californiamilleghia
californiamilleghia UltraDork
11/24/22 8:53 p.m.

And is there any info on the 3D printed body panels that were used to stretch form alloy panels ?
 

sounds like it might be interesting for a few small panels I would like to form , 

Thanks for any info

bertbrown
bertbrown New Reader
11/24/22 9:41 p.m.

In reply to californiamilleghia :

Talk to Allen Buresh at Coachsmithing.  (google Coachsmithing)  He is in Wisconsin.  Allen also shows his work on Instagram.

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