Spitfire specifications from the official Triumph Herald 1200, 12/50, Vitesse & Spitfire Workshop Manual.
Engine
| Number of cylinders | 4 |
| Bore | 2.728 in. (69.3 mm.) |
| Stroke | 2.992 in. (76 mm.) |
| Piston area | 23.45 sq. in. (151 sq. cm.) |
| Cubic capacity | 1,147 cc. (70 cu. in.) |
| Compression ratio | 9.0 or 7.5 : 1 |
| Valve clearances (cold) | 0.010 in. (0.254 mm.) |
| Firing order | 1, 3, 4, 2 |
Performance Data (9.0 : 1 Compression)
| Brake horse power (nett) | 63 B.H.P. at 5,750 r.p.m. |
| Torque | 804 lbs. in. at 3,500 r.p.m. |
| B.M.E.P. | 144 lbs./sq. in. |
Lubrication
| Oil pump type | Eccentric rotor |
| Oil filter | A.C. Delco, Purolator or Tecalemit full flow, external replaceable unit |
| Oil pressure at 2,000 r.p.m. | 60 lbs./sq. in. minimum (4.2 kg./sq. cm.) |
Ignition
| Contact breaker gap | 0.015 in. (0.4 mm.) |
| Spark plugs | Lodge CNY, 1/2 in. reach x 14 mm. |
| Spark plug gap | 0.025 in. (0.64 mm.) |
| Ignition timing (static) | 13° B.T.D.C. |
Cooling System
| Circulation | Impeller type pump with bypass, two-bladed 12.5 in. dia. fan |
| Thermostat opening | 70°C |
| Thermostat fully open | 85°C |
| Radiator | Pressurised finned vertical flat tubes, separate header tank |
| Filler cap pressure | 7 lbs./sq. in. (0.49 kg./sq. cm.) |
Fuel System
| Carburettor | Twin S.U. HS2 Horizontal, Needles A.N. |
| Air cleaners | A.C. wire gauze |
| Fuel pump | A.C. mechanical type Y |
| Fuel pump operating pressure | 1.5 to 2.5 lbs./sq. in. (0.105 to 0.176 kg./sq. cm.) |
| Fuel tank | Non-pressure type, mounted forward of luggage compartment |
Clutch
| Type | Borg & Beck 6.25 in. dia. single dry plate |
| Operation | Hydraulic |
Gearbox
| Type | 4 forward speeds and reverse, synchromesh on 2nd, 3rd and top |
| Top | 1.0 (overall 4.11) |
| 3rd | 1.394 (overall 5.74) |
| 2nd | 2.158 (overall 8.88) |
| 1st & Reverse | 3.746 (overall 15.42) |
Rear Axle
| Type | Hypoid bevel gears, tapered roller bearings |
| Ratio | 4.11 : 1 |
Brakes
| System | Girling hydraulic |
| Front | 9 in. (22.86 cm.) diameter disc |
| Rear | 1.25 in. x 7 in. (3.175 x 17.78 cm.) diameter drum |
Suspension
| Front | Independent with wishbones top and bottom, coil springs, telescopic dampers, anti-roll bar, tapered roller hub bearings |
| Rear | Swing axle type independent, radius rods and transverse leaf spring, telescopic dampers |
Steering
| Type | Rack and pinion, telescopic steering column |
| Caster angle | 4° positive |
| Camber angle | 2° positive |
| King pin inclination | 6.75° |
| Front wheel alignment | Parallel to 1/4 in. (1.6 mm.) toe-in |
| Rear wheel alignment | Parallel to 1/4 in. (1.6 mm.) toe-in |
| Turning circle | 24 ft. (7.32 m.) |
Dimensions
| Wheelbase | 6 ft. 11 in. (2,110 mm.) |
| Track — front | 4 ft. 1 in. (1,245 mm.) |
| Track — rear | 4 ft. 0 in. (1,220 mm.) |
| Ground clearance | 5 in. (125 mm.) |
| Overall length | 12 ft. 1 in. (3,685 mm.) |
| Overall width | 4 ft. 9 in. (1,450 mm.) |
| Overall height (hood up) | 3 ft. 11.5 in. (1,205 mm.) |
| Overall height (hood down) | 3 ft. 8.25 in. (1,125 mm.) |
Weights
| Dry (convertible) | 13.5 cwt. (675 kg.) |
| Complete (incl. fuel, oil, water, tools) | 14 cwt. (710 kg.) |
Capacities
| Engine oil (from dry) | 8 imp. pints (9.6 U.S. pints, 4.6 litres) |
| Engine oil (drain and refill) | 7 imp. pints (8.4 U.S. pints, 4 litres) |
| Gearbox | 1.5 imp. pints (1.8 U.S. pints, 0.85 litres) |
| Rear axle | 1 imp. pint (1.2 U.S. pints, 0.57 litres) |
| Cooling system with heater | 9.5 imp. pints (11.4 U.S. pints, 5.4 litres) |
| Fuel tank | 9 imp. gallons (10.8 U.S. gallons, 41 litres) |
Electrical
| Battery | 12 volt, 38 amp. hours |
| Control box | RB 340 (22 amps.) |
| Generator | C40-1 (22 amps. max output) |
Tyres
| Type | Tubeless |
| Size | 5.20 x 13 (4 ply rating) |
| Pressure (2 up) — front | 18 lbs./sq. in. |
| Pressure (2 up) — rear | 24 lbs./sq. in. |