Built in California by racer Frank Scurria, a Ducati 350 began life as a Ducati 175 single in a 125 F3 frame.
Before this bike existed, there was no Ducati 350, and like the mongrelized Cadillac in the popular Johnny Cash song, it was built one piece at a time. Meet Frank Scurria and his Ducati 175-cum-200-cum-250-cum-350 that had its origins in a 125 F3 frame but eventually found a home in a modified 250 frame.
The pieces to this Italian-American puzzle have their origins in America’s oldest motorcycle road race organization, the California-based AFM (American Federation of Motorcyclists). Among AFM racers in 1959 was a young Frank Scurria, who grew up in Glendale, California. Scurria began road racing his Ducati 200 when he was a teenager and like many young men then and now he was, as he puts it, “a California hot-rodder type who liked working on cars and motorcycles.” Calling him a “hot-rodder type” is shortchanging his talents; Frank Scurria was, and still is, a gifted fabricator who also commands a firm grasp of engineering principles, two qualities that led to the development of his Ducati 350.
Scurria was a skillful road racer, and he campaigned his Ducati 200 with success. When he learned about a special stroker crankshaft developed by master machinist Allan d’Alo that boosted a Ducati 200’s displacement closer to 250cc, Scurria wanted in. With an eye cast towards competing in the 250cc class, Scurria bought one of d’Alo’s flywheel assemblies, and by the end of the 1961 season he was top dog in the AFM’s quarter-liter ranks, winning the class championship.
Scurria didn’t stop there, mapping out a plan to compete in the 350cc class that was ruled by guys riding Manx Nortons, AJS 7Rs and hot-rodded Honda Super Hawks. Initially he wanted to race his bored-and-stroked 200 (by now 247cc) against the 350s, but AFM rules disallowed undersize bikes in the larger classes, so Frank turned to his friend and sponsor, Bob Blair, owner of ZDS Motors in Glendale, for help. Blair supplied Scurria with an over-bore cylinder with matching piston that would bump the engine’s displacement to 254cc. The legal engine worked: “I finished a close second in the 350 class behind an AJS 7R,” recalls Scurria today. He was hooked, and the road to a full-on Ducati 350 suddenly got a little straighter.
“In late 1961 Ducati came out with an over-square 250 that had a bore of 74mm and the same 57.8mm stroke as the 175/200 bikes,” Scurria explains. “The biggest bore I could have without making the cylinder liner too thin was 76 millimeters. With a bore of 76 millimeters and a stroke of 76, I would have a 344cc engine.” Perfect for the 350 class!
“The obvious plus for a 350 Ducati was lighter weight than a 350 Manx or 7R,” Scurria points out. Looking back, he speculates that the Duc weighed about 60-70 pounds less than the full-on 350s. “But I did foresee a few potential problems; the rod-length-to-stroke ratio could be considered marginal and could result in piston failure.” Simply put, piston acceleration and speed was going to be exceedingly high. There was also the issue of the Ducati’s 4-speed transmission, originally intended for a 175cc engine. “I decided there would be no clutch-less or kill-switch gear changes,” he remembers.
Scurria gave d’Alo specs for a stroker crank to push displacement to 344cc. To assure piston dome clearance, he inserted a 0.360-inch spacer plate beneath the bored-out cylinder. Blair also ordered a batch of 76mm pistons from Borgo Piston in Italy. “Unfortunately,” Scurria says, “they were cast pistons, not forged, and there was a piston failure [later in the project’s life].” More about that later.
Before assembly, Scurria visited master engine builder C.R. Axtell, who was among the first speed merchants in Los Angeles to have a flow bench for motorcycle engines. Axtell took one look at the bare cylinder head’s ports and told Scurria, “You can make this a little better, but you’ll never make it really good,” pointing out that there wasn’t enough metal within the port area to do much sculpting to fully correct the problems.
Axtell made a few suggestions to improve flow, which Scurria followed to a T, weld-filling some areas so he could alter the port angle from 9 degrees to 3 degrees for improved flow. Axtell stressed that the important thing was to shape the port angle in relation to the valve, not the horizon. Scurria also fabricated a thick, wedge-shaped flange that tapers in two planes for the carburetor spigot mount so that a larger 32mm Dell’Orto SSI carburetor (and later an Amal GP2) would clear the frame tubes on the right side. He was careful not to remove much material from around the valve guides, to assure adequate support for the valves at high rpm. Scurria recalls that he did a lot of handwork using riffler files to shape the port around the valve guide boss.
The intake valve was 1.59 inches (40.4mm) with a 7mm stem, and the exhaust 1.45 inches (36.8mm) with an 8mm stem. Art Sparks and Tim Witham, better known as S&W, provided the coil valve springs. Selecting a high-performance camshaft proved a problem because there really wasn’t a clearing house for Ducati racing cams in 1962. After trying a modified cam set to F3 specs, Scurria received a gift from Blair: “Bob just walked up to me in the shop one day, handed me a cam and said it was for my 350 engine.” It was the grind that led to the Ducati kit cam known later among racers as the Daytona Cam. It shared the F3’s timing, but offered more lift.
He sandblasted the engine cases, cylinder and head before anodizing them black for improved heat transfer, and the new connecting rod was X-rayed, polished and shot peened. He ground off excess metal from the piston’s underside for lightness, and he knife-edged the piston skirts to reduce drag on the cylinder wall. An internally tapered and lighter wrist pin from a 250 F3 further reduced weight. He set combustion chamber squish clearance at 0.038 inch. The compression ratio factored out to be 10.5:1.
Further engine weight was shed thanks to constant-loss battery ignition, which allowed for the stator and flywheel to be discarded. “Only the steel flywheel center was used, as a spacer for the crankshaft primary gear,” Scurria explains. He also drilled the engine mounting bolt holes to 0.375 inch to accept aircraft-grade 12-point bolts to help create a more rigid chassis.
Scurria also found himself navigating through unchartered waters when he selected an exhaust system for the 350. He experimented with pipe diameters from 1-5/8 inch to 1-3/4 inch, ultimately settling on a stepped pipe (and people today think that’s a fairly new concept!), measuring 1-5/8 inch at the exhaust port, stepping up to 1-3/4 inch farther downstream. Header pipe length varied from 32 to 34 inches, but the real mystery remained in the megaphone’s shape. The Manx megaphone that he first tried was crowd-pleasing loud, but it created a flat spot through the mid-range engine speed. “The long megaphones seemed to work better than the shorter ones, the power was better,” Scurria says, adding, “but the best one was the Axtell design; it’s what’s on the bike now.”
Initial speed testing took place on the service road running adjacent to the Los Angeles River near Interstate 5 just down the block from ZDS Motors. “I could make a couple of high-speed passes and then scoot before the police came,” admits a more mature (read: responsible) Frank Scurria today. “A small motorcycle running over 100mph and passing cars next to the freeway caused quite a few double takes. One was a CHP [California Highway Patrol] giving me a wide-eyed stare.”
The bike proved fine, so Scurria packed it on the trailer for a trip to Willow Springs Raceway out in the Mojave Desert to do further testing. “In those days, Willow Springs was just 2.5 miles of race track in the middle of the desert, without fences or barriers. There wasn’t anyone to stop us [from testing].”
Those early tests revealed weak brakes, so the 125 F3 frame Scurria was using was fitted with a large Amadoro four-shoe front brake, with a smaller Amadoro brake on the rear and 18-inch rims for both wheels. The first race proved how under-engineered the frame was for the “big” engine. A fellow competitor described the bike’s wobbling and weaving as “a crash in progress that never quite made it all the way to the ground.” Scurria agrees: “It seemed both wheels were never going in the same direction at the same time.”
A re-think led to a second chassis based on a late-generation 250 F3 with Oldani brakes and 19-inch rims. “It was a little heavier than the 125 F3 chassis, but it handled so much better,” reflects Scurria. “With this new chassis I could beat most of the 350 Hondas [CB77] and run with the best 7R and 350 Manx.”
By now Scurria was a one-man R&D department. Buoyed by his progress he decided to up the ante, placing the crown jewel — the sweet-running 350cc engine — into an original 1961 Ducati 250 road frame that was “highly modified and much lighter.” Only the frame’s backbone, front down tube and steering head remained in stock configuration. Mods included repositioning the front down tube forward about 5/8 inch at the bottom and fabricating a complete rear section using 7/8 inch diameter, 0.065-inch wall 4130 chromoly tubing. Additional strength came from an all-new, one-off, rectangular cross-section swingarm. Despite the swingarm’s massive size compared to stock, Scurria says it weighed about the same. It’s also stiffer and about half an inch longer to improve weight distribution.
The swingarm pivot is 2-3/8 inches longer than stock, and constructed from machined 4130 chromoly tubing. “I didn’t have access to a TIG welder and didn’t even know how to TIG weld, so I fabricated the steel parts, tacked them together with an oxyacetylene torch, and then took them to a welder a few miles from ZDS who finished the job with TIG welding,” Scurria remembers.
All that hard work paid off. The frame, with swing arm, tips the scales 10 pounds less than a standard 250 F3 frame. Final suspension includes a 35mm Ceriani road race fork, 18-inch rims front and rear, and a 230mm Oldani front brake. The rear brake is based on a standard Ducati road hub, but with a cooling air scoop. Italian bike aficionados might notice how it resembles brakes found on many Grand Prix race bikes from the 1950s.
Finally, Scurria called on another early AFM stalwart, “Dirty” Dick Kilgroe, owner of Cupless Plastics, for the fairing. Kilgroe started with a Peel fairing — popular among road racers in those days — modifying it to fit the small Ducati frame. Peel fairings aren’t as abundant today, so when Scurria began the bike’s restoration a few years ago, he made a buck to form a similar fairing, then had AirTech (airtech-streamlining.com) in Vista, California, build the replica, which, by the way, is now in AirTech’s regular catalog. Geoff Giammarco gets credit for the lustrous metallic silver paint job.
All of Scurria’s original work paid off because the little Ducati, checking in dry at 217 pounds, proved competitive against the 350 field in 1963. The bike’s first win happened during a two-day event at Willow Springs. The teeth on the clutch gear had sheared off during Saturday practice, prompting Scurria to return to his motel where he set up shop to disassemble the engine. By chance, members of Berliner, distributor for Ducati in the U.S., were in Southern California visiting ZDS Motors, and among the contingent of VIPs was Heinz Kegler, Berliner’s Norton specialist. Kegler gladly switched hats for the day, donning one with a Ducati logo so he could help Scurria repair the engine. While Scurria tended to the engine’s damaged internals, Kegler hustled back to Glendale to get replacement parts, including new primary gears.
“The driving gear at the end of the crankshaft was steel, but the driven gear, which is also part of the clutch housing, was made of cast iron,” Scurria recalls. Cast iron proved to be the weak link.
After the all-nighter, Scurria and Kegler buttoned up the Ducati engine in time to make it to the grid for the 350 race. “The first win for a 350 Ducati anywhere in the world,” Scurria proudly says, adding, “I wish I could say that I won the 1963 350-class championship, but no, I didn’t.” His Ducati was third in points behind a Honda and AJS. However, he looked towards 1964 with optimism. “Other than the primary-gear failure, there weren’t any problems with reliability,” Scurria says. “I started the 1964 season thinking I was riding a bulletproof bike.”
Early in the 1964 season the engine burst along Willow Spring’s high-speed back straight. “At maximum revs [9,000 rpm] the top half of the piston came off at the pin, hit and bent both valves and ruined the valve guides. The cylinder had deep gouges in the liner from the piston pin, and the rod was bent.” Worse, though, was the beautiful crankshaft, which had begun to separate from its flywheels. Party over.
Scurria’s never been a quitter, and although he parked the Ducati 350 for good, he continued racing. “Because of the level of damage, unavailable parts and my move into the 500 class with a new Norton Manx, the engine was never rebuilt,” Scurria says. Instead, it was disassembled, the engine parts stashed in boxes and the rolling chassis parked nearby until it eventually was sold.
However, customer inquiries to Berliners’ headquarters in New Jersey about Ducati’s “350” model showed that Scurria’s project hadn’t lost traction. Late in 1963, Mike Berliner called Bob Blair to ask about the Ducati 350 in California that everyone was talking about. Blair explained the situation, and Berliner promptly asked Scurria to send the kind folks at Ducati the specifications and other data for the engine.
“On Dec. 3, 1963, I sent drawings and all the specs of my bike to Dr. Giuseppe Montano, thinking nothing would come of it,” Scurria recalls. A week later, however, Dr. Montano replied, explaining that he was turning over Scurria’s fact sheet to Ducati Studies Office for review. About a year later, Blair informed Scurria that Ducati was going to offer a 350cc model that was considerably like his 350.
In 1965 Ducati sent factory rider Franco Farne to race a 350cc prototype at Sebring, in Florida. The race included bikes with engine sizes ranging from 251cc to 700cc. The little Ducati finished 11th overall and first in class, and to celebrate the occasion, Ducati named the forthcoming production model the Sebring. By all rights, though, and with due respect to Signore Farne, the first-ever Ducati 350 should have been called the California, or something to that effect. For his foresight and efforts, Ducati promised Scurria that they’d supply him with a new 350cc racer. “It never arrived,” Scurria says.
Even so, the story has a happy ending. In 2002 Scurria met Ducati parts specialist Steve Allen of Bevel Heaven (bevelheaven.com). Allen posted articles on his site about Scurria’s Ducati past, including a request to readers who might know the whereabouts of Frank’s old race bikes. A few years later someone responded, claiming to have an old Ducati that might be Scurria’s. “When I saw what he had, I knew instantly it was the final 250 road frame,” beams Scurria.
He obtained and restored the bike to its former glory. Although various components were missing, they’ve been replaced, including the Oldani front brake that a friend located in Italy. The engine is a runner, right down to the Kulan camshaft, which happens to be the first cam that Blair passed along to Scurria for the project. And that alloy gas tank? It’s not original, but it resembles the first one. And more to the point, the replacement was fabricated by Scurria.
The restored racer appears occasionally at bike shows. Beautiful in every way, it’s an important machine, worthy of appreciation for its unique place in Ducati history, a special that inspired a factory model. As Scurria says, “We weren’t trained engineers, just California hot rodders. But we didn’t know what we couldn’t do, so we just did it.” MC