Guide: Ford Shelby Mustang GT350 Series 1 1965 / 1966
Background
Ford’s Total Performance programme of the 1960s spawned some legendary machinery of which the four-time Le Mans winning GT40 is particularly revered.
The company’s engines were also used to power Jim Clark’s 1965 Indy 500-winning Lotus and considerable support was put the way of Carroll Shelby for his Cobra endeavours.
Later there was the dominant Cosworth DFV F1 engine (bankrolled by Ford UK) plus saloon racers and rally cars too.
While all this came at considerable expense, Ford capitalised by extending the programme to include a stunning new high performance production model called the Mustang.
Originally conceived as a strict two seater, Ford senior executive, Lee Iacocca, realised the new car would be a massive seller if it could be made into a four-seater suitable for everyday use. Ford agreed and the move paid off. 22,000 Mustangs were sold on the first day of availability in April 1964 and more than 100,000 had rolled off the production line within four months.
Inside two years, over one million Mustangs were sold - it was well on the way to becoming Ford’s biggest seller since the Model T.
Based on conventional Ford underpinnings, the chassis, suspension and drivetrain components were all derived from the Falcon and Fairline. The chassis itself was a unitary platform sourced from the 1964 Falcon.
In August 1964, Ford commissioned Carroll Shelby to produce a further uprated Mustang that could rival Chevrolet’s Corvette, albeit in a more practical day-to-day package.
Shelby’s operation would also handle a competition programme that included an attack on the SCCA’s high profile B-Production championship.
The result was the Shelby Mustang GT350, all examples of which initially started life as Wimbledon White K-Code DSO fastbacks with 271bhp 289 cubic inch V8s and black interiors.
DSO referred to Domestic Special Order - the unique blend of upgrades these cars were built with before being dispatched to Shelby.
For example, the front disc brakes were kept, but sintered metallic pads were used instead of the softer stock items. At the rear, station wagon drum brakes with larger metallic-lined shoes were installed.
There were also 9-inch Detroit Locker limited-slip differentials, under-hood ‘Export’ bracing and close-ratio T-10 Borg Warner four-speed gearboxes with special lightweight aluminium casings.
Cars were shipped from Ford’s San Jose plant to Shelby American’s Los Angeles facility without hoods, grilles, rear seats, exhaust systems or emblems.
Then the transformation really began.
The SCCA’s B-Production rules stated that qualifying cars could run either modified suspension or engines, but not both. Shelby opted for the modified engine route and thus the suspension was created from existing Ford components.
Chassis
The front-suspension mounting points were re-positioned and the A-arms were lowered which reduced ride-height at the front by an inch. The live rear axle was held in place with a semi-elliptical leaf spring and stronger torque reaction arms on top of the axle itself.
Adjustable Koni shocks were installed plus new rear traction bars and thicker anti-roll bars.
Shelby further enhanced the GT350 with a quick-ratio steering rack and an oil cooler for the differential.
The stock Mustang radiator was replaced with a much bigger unit from the air-conditioned Galaxy 500.
The battery was initially repositioned from under the hood to the trunk, but following complaints from owners about fumes and corrosion, it soon reverted back to the original location.
15-inch wheels were available in two styles: white-painted steel or cast magnesium Crager rims. Both types originally came shod with Goodyear Blue Dot tyres.
Engine / Gearbox
Engines were based on Ford’s new Hi-Po 289 small block V8 that produced a respectable 271bhp direct from the factory. This pushrod-operated all-iron motor displaced 4727cc thanks to a bore and stroke of 101.6mm and 72.9mm respectively. The compression ratio was 10.5:1.
Once on Shelby’s production line, each motor was equipped with a new aluminium Cobra hi-rise intake manifold to replace the stock cast-iron item.
A Holley four-barrel 715-cfm carburettor was designed not to starve or flood during hard cornering.
There were lightweight tubular Tri-Y exhaust headers that fed straight-through pipes and low restriction glass-pack mufflers. The exhausts were re-routed to exit ahead of the rear wheelarches.
Engines were dressed with a chrome air cleaner, finned aluminium Cobra rocker covers and a cast aluminium oil pan.
All told, the revamped motor produced 306bhp at 6000rpm and 329lb-ft at 4200rpm.
Transmission was via the aforementioned close-ratio Borg Warner T-10 four-speed gearbox complete with special lightweight aluminium casing, a 9-inch Detroit Locker limited-slip differential and single-plate clutch.
Bodywork
Externally, the GT350 could be identified by its hood-mounted air scoop.
The new fibreglass front lid was held in place with fastening pins.
All GT350s were initially painted Wimbledon White with Guardsman Blue stripes and matching GT350 sill decals.
Interior
As the SCCA B-Production requirements only permitted two-seats, Shelby received all cars from Ford without back seats. They were instead fitted with a simple fibreglass panel that held the spare tyre in place.
The dash was modified to incorporate a central pod that housed a large tachometer and smaller oil pressure gauge.
Directly behind the new wood-rimmed three-spoke steering wheel was the original Mustang’s rectangular instrument binnacle. Small circular dials for fuel and water temperature were housed at either end and a sliding speedometer was located in between.
Competition safety belts were combined with otherwise standard Mustang seats.
Black vinyl was used to upholster the dash, seats, door panels, sidewalls and the rear storage platform that housed the spare wheel.
Weight / Performance
Weight was 1265kg which represented a 102kg reduction compared to stock Mustang.
The GT350 had a top speed of 138mph and 0-62mph time of 6.6 seconds.
1965 Model Year Production
At least 100 production units of the new model had to be completed to meet the SCCA’s homologation requirement. With this in mind, Ford initially only shipped the required number of their specially optioned Mustangs to the Shelby American plant.
By September 1964, the first GT350 had been built.
The remainder were ready for inspection by December and homologation was duly granted in January 1965.
Shelby American then moved to its new production facility at the Los Angeles International Airport.
The GT350 made its public debut on January 27th 1965.
The entire production run was finished by July 9th. 516 had been completed, all of which were left-hand drive.
An additional 200 1965 versions were held over and titled as 1966 model year cars.
1966 Model Year
For the 1966 model year, the GT350 underwent a variety of changes, primarily because Ford wanted to make more money.
Most significantly, the rear seats were re-instated and a wider choice of colours was offered.
The 1966 model year also saw the introduction of a Hertz rental version followed by a supercharged GT350 and even a tiny number of Convertibles.
All 1966 model year GT350s were completed with 14-inch wheels instead of the 15-inch rims used beforehand.
The lowered A-arms used in 1965 were ditched for standard parts and the rear traction bars originally installed over the axle were exchanged for less complex units that now went underneath.
Outside, the elegant sail panel extractor vents were replaced with Plexiglas quarter windows. The fuel-filler cap now bore a Cobra logo rather than a Mustang.
To further broaden the GT350’s appeal, four new exterior colours were introduced; Ivy Green, Candyapple Red, Sapphire Blue and Raven Black could all be specified with contrasting stripe kits.
Customers could also select a set of new chrome-rimmed Magnum 500 wheels.
Although the rear seats officially returned, 95 1966 model year GT350s were built as two-seaters.
Other cockpit changes saw an oil pressure gauge added to the instrument panel while the 1965 instrument pod was discontinued in favour of a separate tachometer mounted on the dash.
By August 1965, production of the proper 1966 model year version was underway. It went on sale in October 1965. The first 300 or so were completed without the GT350 tailgate badge.
Hertz GT350
In November 1965, Shelby made a proposition to the Hertz car rental firm about producing a special edition GT350 that would serve as a useful publicity tool for both companies.
Hertz liked the idea and a prototype was quickly up and running.
A contract for 200 cars was soon increased to 1000 units, all of which were produced in the 1966 model year.
These Hertz derivatives were supplied with special Gold sill stripes that read ‘GT350H’. Many were also kitted out with matching centre stripes. Around 80% were painted Raven Black and the remaining 20% was split primarily between Wimbledon White and Candyapple Red.
Quickly nicknamed Rent-a-Racer, some Hertz customers headed straight for the track while others swapped the powerful Shelby motors for the standard V8s in their own Mustangs.
All Hertz GT350s got Magnum 500 wheels as standard. Early examples came equipped with the Borg-Warner four-speed manual. This was replaced by Ford’s own Toploader unit after around 250 had been completed.
Automatic Gearbox Option
When the C4 automatic transmission was introduced as an optional extra, many customers (including Hertz) began to order GT350s equipped as such. Autolite 4100 carbs were used for this application as opposed to the Holley 715-cfm.
GT350 Convertible
In addition to building cars for Hertz, Carroll Shelby decided to treat himself, his secretary and a handful of close associates to a batch of specially developed GT350 Convertibles.
Not offered for public sale, six were made (all in different colours).
Chassis numbers for these cars ranged from 6S2375 to 6S2380.
Paxton Supercharger Option
Eleven GT350s were also equipped with Paxton superchargers during the 1966 model year.
Paxton’s Joe Granatelli had approached Shelby with the concept in early 1965. The idea was for a Paxton supercharger kit to be offered as an official option. Shelby lent Granatelli a ’65 GT350 (chassis 5S425) for use as a development mule.
The prototype was completed in July 1965 and Shelby was apparently bowled over by the car’s performance. He went on to order 500 Paxton kits for installation by special request.
These supercharged GT350s also came with Autolite 4100 4V carburettors and Carter high-volume fuel pumps.
Inside, there were Paxton gauges for the manifold pressure and vacuum, both of which were mounted under the centre of the dash.
With an output of between 380bhp and 400bhp, these Paxton supercharged Mustangs were the quickest road-going GT350s of all. 0-62mph took under six seconds and top speed was nearly 150mph.
End of Production
By June 1966, specifications for the redesigned 1967 model year GT350 and an even bigger-engined GT500 were finalised. Production began in September 1966.
By this time, 2388 1966 model year GT350s had been manufactured.
1368 of these were stock GT350s and 1001 were Hertz variants. There were also six Convertibles and eleven supercharged examples.
Text copyright: Supercar Nostalgia
Photo copyright: Ford - https://www.ford.com
