1960 OSCA 1600 GT Zagato

The OSCA 1600 GT Zagato is perhaps one of the most underappreciated and misunderstood GT cars of the post- war era. Signaling a close to the Maserati Brothers dynasty and remaining in the shadow of the legendary OSCA MT-4 (overall winner at Sebring in 1954), the 1600 GT emerged with a very different goal in mind; to produce an agile and stylish coupe. The result was an international success. The OSCA 1600 GT Zagato prototype debuted at the 1960 Turin Auto Show. The car was tested by Lodovico Scarfiotti (Auto Italiana Sport, February 1, 1961), receiving rave reviews. The Maserati Brothers knew they had a winner and OSCA 1600 GT Zagato production quickly commenced.

An All-New Tubular Chassis

The 1600 GT was built on a specially designed tubular OSCA chassis, not on a Fiat 1500 or 1600 unit as some authors have incorrectly described. The chassis for the 1600 GT was constructed at the OSCA factory with some components subcontracted out. The wheelbase was 2250-mm (88.5 inches), 50-mm longer than the MT-4. The majority of cars were equipped with independent suspension front and rear, although a few cars had live-axle rear suspension. The rear live axle, also known as the Ponte Rigido (PR), was a less expensive alternative, but also used on the Le Mans Experimental flat- topped (“un-bubbled” roof) OSCA Zagato (chassis # 0036).

In Orsini and Zagari’s definitive OSCA book, a reference photo shows a bare chassis (page 325) with the caption (translated here from Italian to English): “The chassis was made up of a primary structure in round tubing, and a secondary one in boxed sections. The assembly was done in the factory, and partially by specialized outside workshops in order to speed up the production process.”

The Marvelous OSCA Twin Cam Engine 

The casting for the 1568-cc (Bore = 80-mm; Stroke = 78-mm) OSCA twin-cam 1600 GT engine was a tour de force of displacement balancing power. A derivative of the Maserati designed Fiat 1500 power plant (Bore = 78-mm; Stroke = 78-mm, same as the OSCA MT-4) overbored to 80-mm, the five main bearing engine was inherently strong and potent. Specifications dictated by the OSCA engineering team were carried out at the Fiat foundry under the watchful eye of the Maserati Brothers. The engine castings destined for the coupes were delivered to the OSCA factory and carefully machined and balanced to exact tolerances. While the overall configuration of the OSCA 1600 engine was similar to that of the Fiat 1600, there were many important differences.

The OSCA 1600 GT engine block was machined with larger oil passageways and had other important modifications to allow for greater oil volume and flow. The OSCA block was constructed with a mechanical oil pump and a vertical oil filter canister. The Fiat block had a centrifugal oil pump with the oil filter screwed into the block. Additionally, an alloy front cover and oil pump assembly was fitted to the OSCA engine. The OSCA 1600 engine was stamped “OSCA” while the Fiat block was stamped “Fiat.” Most notably to viewers of this engine, OSCA factory name and numbers were cast or stamped into the unique parts. The connecting rods, pistons and five-main-bearing crankshaft of the OSCA 1600 were forged, while the Fiat units were cast. Finally, the oil pan of the OSCA engine was cast and machined, resulting in a delightful finned aluminum construction.

The OSCA 1600 Zagato came in four basic variants: 

GT – One 28/36 Weber twin-choke carburetor, weight 862-kg, 95 bhp (soon abandoned); GT2 – Two 38 Weber twin-choke carburetors, weight 862-kg, 105 bhp; GTV – Two 42 Weber twin-choke carburetors, weight 862-kg, 125-bhp; and GTS – Two 42/45 Weber twin-choke carburetors, weight 800 kg, 145 bhp.

Bubbles Galore

The Zagato coachwork for the OSCA 1600 came from the gifted hands of Ercole Spada who later penned the astounding Alfa TZ and Aston Martin DB4GT Zagato. All 1600 GT Zagatos were constructed of aluminum using traditional wooden bucks and hand-formed body panels.

According to Raffi Minasian, Automobile Designer and Professor of Design at California College of the Arts, “The OSCA 1600 Zagato coachwork is perhaps one of the most visually dynamic coupe expressions from this coachbuilder. The low frontal area and gentle articulating beltline bring the eye low to the ground. The tall upper and open greenhouse (required for occupant comfort) pulls the eye upward, into the bodywork, creating a stunning coupe without appearing bulbous, truncated or visually stunted. The ‘bubbles’ create musculature that contrasts the scale of the car, but does so with tapered elegance. Small cars are challenging to design with proper proportions, and the 1600 OSCA Zagato is proof that Italian artisans were masters of form and function in metal sculpture.”

The most common style produced by Zagato for the OSCA 1600 had a double-bubble roof with rear vent openings (to the best of our knowledge, there were no OSCA Zagato coupes that were built with a double-bubble roof that did not have rear vent openings). The rear vents had clever wedges inside the cockpit which could be opened to allow warm air (or a cloud of cigarette smoke) to exit the driver’s compartment, or closed if the weather was cold. There was more than one variation in the design of the grille opening on these cars. The Amadori magnesium wheels and seats on some of the earliest cars differed a bit from those in later cars. The prototype and some production cars were equipped with comfortable sports seats. Other examples left the factory with the rather Spartan-looking lightweight Zagato seats as also used in the Alfa SZ and some Abarth coupes. These Zagato seats are actually rather comfortable. Chrome-plated front and rear bumpers were fitted to many of the cars destined for road use.

A small number of racing GTS cars had perspex-covered headlights that were faired in, continuing the front fender line. Some race prepped cars were fitted with perspex windows and some with slightly lightened bodies. Another racing feature on some cars was the use of a large (87- liter) fuel tank as compared to a stock 50-liter tank. One Zagato double-bubble (the 1960 Turin Auto Show car) was built with larger rear vent openings and can be seen on pages 324 and 325 of the Orsini book. Zagato also built a one-off 1600 GT example with an unbubbled roof (chassis # 0036) that was raced at Le Mans in 1962 and Sebring in 1963.

Production and Chassis Numbers

Most OSCA 1600 GT owners and aficionados believe that the often quoted production number of 128 cars is inflated. Based on a review of the published Registry data available, it is more likely that fewer than 75 1600 GT cars were built. Of these, likely no more than 50 examples were bodied by Zagato. An article in the March, 1998 issue of Ruoteclassiche Magazine estimated that roughly 30 OSCA 1600 GT Zagatos had survived. The two most often quoted sources of information on the OSCA 1600 GT are Orsini’s book and The Italian Car Registry by de Boer. It is important to note that the Orsini and de Boer rosters and chassis numbers are not in agreement regarding all details. Of the 56 chassis numbers listed on the Orsini roster, 32 were bodied by Zagato, 22 by Fissore, and two by Boneschi.

Information regarding OSCA 1600 GT production and chassis numbers can be found on pages 273 and 274 of de Boer’s The Italian Car Registry (1994, First Edition). The de Boer roster contains chassis numbers ranging from 001 to 00140, but there are sequencing gaps. The largest such gap in de Boer’s roster occurs between chassis #s 0037 and 0070. Of the 70 1600 GT chassis numbers listed, 44 are noted as definitively being bodied by Zagato, two additional cars may have been bodied by Zagato (chassis #s 0011 and 00100) and one was “badged” by Zagato (chassis # 00140). In addition, de Boer lists 20 cars with histories, but without chassis numbers at the end of his roster in note fashion. Here, de Boer reports that six of these cars were bodied by Zagato, however, it is unclear whether or not the histories of these six cars belong to cars in the chassis number range of 001 to 00140.

Racing

Two OSCA 1600 GT Zagatos (chassis #s 007, a double-bubble roofed car and chassis # 0036, the only un-bubbled roofed OSCA constructed by Zagato) were entered in the Le Mans 24 Hours in 1962. The flat-topped Zagato was fitted with the all-new twin-plug head that had not yet been homologated. Both cars competed as an “Experimental.” Racing car number 37, George Arents and Jose Behra completed 227 laps (20th overall) before expiring with a gearbox problem. Driving car number 36, John Bentley managed only 13 laps before an engine problem ended his race.

Back home in Italy, the 1600 Zagatos were raced primarily in hillclimb events by privateers. A factory works development car was campaigned by OSCA faithful Gianfranco Stanga at several venues. Stanga’s earliest success in the car came with a 1st-in-class at the Trieste-Opicina Hill Climb in July of 1962. Stanga later scored an overall win at the Selva di Fasano Hill Climb in August of ’62.

Two OSCA 1600 Zagatos competed at Sebring in 1963. Car #57 (chassis # 0036, unbubbled roof), entered by Luigi Chinetti Sr. and driven by Thomas T. Fleming, Harold Baumann and Ray Heppenstall finished 5th in class despite a race-ending problem on lap 139. Robert Publicker’s entry, car #56, failed to finish with a differential problem on lap 41. Mario Nardari finished an impressive first-in-class in an OSCA 1600 GT Zagato (chassis # 00101) at Round 6 of The International Championship of Manufacturers Race at the Consuma Hillclimb in June of ’63.

OSCA 1600 owners continued to race their machines in the Italian hill climbs in ’63 and ’64. By 1965, it was becoming obvious that the cars were no longer competitive, as the Alfa TZ was now on the scene. Designed as a purpose-built racer, the TZ was simply faster in every way.

Owning an OSCA 1600 GT Zagato

From the outside, the OSCA 1600 GT Zagato appears to be a very small car. However, once inside (the best entry technique is bottom first, then swing the legs in) there is a surprisingly vast amount of both leg and head room. Seating is comfy and allows for long legs. Nicely balanced at the H-Point, drivers are well nestled into the car without feeling hunkered down.

Turn the key and there’s an immediate response as the car jumps to life. The engine is smooth once you are under way. Cam timing on ex-racecars can be a bit wild, with bunny-hops below 3000 revs. Unless you are racing on a circuit, 6500 rpm is plenty to get your heart and the car’s power plant going hard. One of us (A.C-F) has owned two of these cars; an ex-hillclimb GTV example with 120 bhp, and a far more exotic GTS. The latter had the twin-plug head removed as these were apparently extremely difficult to set up properly and the twin-plug configuration left no room for larger valves. Today, it has become relatively easy to massage an additional 25 bhp from a properly prepared single-plug street engine, and all-out racing engines are now capable of 165 bhp with good reliability.

The OSCA 1600 GT Zagato is a car that tempts you to go for it…drive fast and take chances. Plant your foot firmly on the go-pedal and the needle races toward the 7200 rpm redline with the twin-cam singing like a great Italian tenor. Shifting is a wonderful thing as the gearbox is quick and precise. The factory clutch can be a bit grabby, but swapping in a modern replacement makes all of this disappear.

Handling and steering are extremely precise, as one would expect from any OSCA. This gives rise to the feeling that you simply need to “think” the car around the twists. The four corner disc brakes—remember this car was designed in ’59-’60—result in impressive stopping power. Any signs of breakaway at the rear are easily controlled under most conditions with a quick bit of correction at the wheel, making the car huge fun to drive. This is a car that rewards the exacting and enthusiastic driver, but for those accustomed to larger-displacement engines, it may not excite in the same thumping way. Forward vision is excellent, but the rear view is somewhat distorted by the steep angle of the glass (a side mirror is a must). Maintenance is relatively easy as the engine shares many components with the Fiat 1600S. There can be some issues sourcing things like suspension bushings, but Fiat 1100 parts can easily be turned down to fit. Keep everything well greased, check the clearances at regular intervals, run with clean oil at all times and be diligent about the usual care as with any vintage sports car.

The OSCA 1600 GT Zagato is an equally exciting car to behold and pilot. Other than a few one-offs, it is the only OSCA that can be practically driven on open roads and on touring events. These cars were born from the heart and soul of the Maserati Brothers and hit on all major points: ultra-low production, Italian, OSCA, aluminum body, Zagato coachwork with an exotic, vented double-bubble roof, twin- cam engine of 1.6-liters, independent suspension front and rear, disc brakes and the vast, incomparable history of the Maserati Brothers.

For the longest time these cars were sleeping giants and prices were very reasonable. Times have changed, and the OSCA Zagato is now on its way to becoming very expensive…if you can find one. Still less than half the price of an MT-4, this car offers any collector great value as a road/event car and as a shrewd investment. After all, can you name another ultra-low production Zagato-bodied double-bubble car over 1.5- liters that can be bought for less than half a million U.S. dollars?