Reference
Triumph Stag specifications and dimensions
Factory specifications for the Triumph Stag (1970 to 1977). The figures below come from Repair Operation Manual data, cross-checked between independent sources and against this archive's own pages. Where sources disagree, the disagreement is shown rather than resolved silently. Where a figure cannot be corroborated at all, it is omitted rather than estimated.
Engine
Triumph's own 3.0-litre V8, 90°, single overhead camshaft per bank, cast-iron block with aluminium heads.
| Specification | Figure | Notes |
|---|---|---|
| Type | Triumph 90° V8, SOHC per bank | |
| Capacity | 2,997 cc | |
| Bore × stroke | 86.0 × 64.5 mm | Oversquare |
| Block | Cast iron | |
| Cylinder heads | Aluminium alloy | |
| Compression ratio | Home and general export: 8.8:1 to 1972, 9.25:1 from 1973. USA: 8.8:1 to 1971, 8.0:1 in 1972, 7.75:1 in 1973 | Repair Operation Manual Section 05, Engine Tuning Data, page 05-1, read at source. The archive previously published 8.8:1 as a single figure and recorded the other numbers in circulation as a disagreement between sources. There was no disagreement: the ratio changed by year and by market and each source was quoting a different car. The manual marks the 1973 USA figure as especially applicable to Australian market vehicles built to 1976 emission requirements |
| Fuel system | Twin Zenith-Stromberg 175, the type varying by year and market | Repair Operation Manual Section 05, page 05-1. 1970: CD2S home and general export, CDSE USA. 1971: CDS or CDS(E)V home and general export, CDSEV USA. 1972 onwards: CDSEV both. 1974 to 1976: CD2SEV home and general export. The archive previously published CDSE as the specification, which is the 1970 USA unit |
| Maximum power | 145 bhp @ 5,500 rpm | |
| Maximum torque | 170 lb·ft @ 3,500 rpm | |
| Engine character | Interference |
Factory redline figure omitted pending primary-source verification.
Cooling system
| Specification | Figure | Notes |
|---|---|---|
| Thermostat | Opens at 82°C | Repair Operation Manual Section 26 and the factory General Specification Data |
| System pressure | 13 lb/in² (0.91 kg/cm²) | The factory figure, given for early cars. The Vintage Triumph Register records that 20 lb caps became standard on later Stags and recommends the higher rating |
| Circulation | Impeller-type pump, driven through skew gears from the jackshaft | Mounted high in the engine, which is why coolant loss stops circulation before the gauge looks alarming |
| Fan | 13 blades, 16.5 in (418 mm), with Torquatrol viscous coupling | The coupling slips to hold fan speed to about 2,500 rpm, limiting noise and power loss at high engine speed |
| Antifreeze | Solutions meeting BS 3152 | The factory specification names no brand |
The thermostat must carry a blanking disc to close the bypass port. Most do not, and one that does not will make the car run hotter. See the cooling upgrades guide.
Valve clearances
| Specification | Figure | Notes |
|---|---|---|
| Exhaust | 0.016 to 0.018 in (0.41 to 0.46 mm) | Repair Operation Manual Section 12 and Rimmer Bros agree exactly. Rimmer states cold |
| Inlet | Disputed. 0.008 to 0.010 in per the Repair Operation Manual Section 12; 0.006 to 0.008 in (0.15 to 0.20 mm) per Rimmer Bros, stated cold | The two published ranges touch at one value and one only |
| Exhaust, target | 0.017 ± 0.001 in | The figure the manual's own worked examples aim at when selecting a pallet, which is the mid point of the published range rather than a different specification |
| Inlet, target | 0.009 ± 0.001 in | As above. An owner choosing a pallet should be aiming at the target rather than at the edge of the range |
| How it is adjusted | By selective pallets, not by a screw and locknut | The camshaft has to come off, and the pallet under each tappet is measured with a micrometer and swapped for one of a different thickness |
| Pallet thickness range | 0.070 to 0.114 in, in 0.001 in steps | Repair Operation Manual Section 12 |
The archive has now read the manual itself, and the hot or cold question is settled as far as it can be. Neither Section 05, Engine Tuning Data, nor Section 12.29.48, the valve clearance operation, gives any hot or cold qualifier at all. But the operation explains why. Checking the clearance means removing the air cleaner, the distributor cover and the camshaft covers and putting a feeler gauge between each cam heel and tappet; adjusting it means lifting the camshaft off and swapping selective pallets measured with a micrometer. That is not a procedure anyone performs on a hot engine, so by the time a reader is taking a measurement the engine is necessarily cold. The question only arises where there is a screw and locknut to turn, and the Stag has none. On that reading, which is the archive's own and not the manual's words, Rimmer Bros stating cold is not a contradiction of the factory but a statement of the obvious. The inlet disagreement remains: the manual gives 0.008 to 0.010 in and Rimmer 0.006 to 0.008 in, and the two ranges still touch at exactly one value.
Selecting a pallet
The Stag has no screw and locknut. Clearance is set by swapping the selective pallet that sits between the valve and the cam follower, and the arithmetic is simpler than the job. Measure the clearance, measure the pallet, and change the pallet thickness by the amount the clearance is out. The sign inverts: a thicker pallet gives less clearance.
The manual works two examples. An exhaust valve measuring 0.022 in against a 0.017 in target is 0.005 in too slack, so its 0.090 in pallet is replaced with a 0.095 in one. An inlet valve measuring 0.004 in against a 0.009 in target is 0.005 in too tight, so its 0.100 in pallet is replaced with a 0.095 in one. Pallets run from 0.070 to 0.114 in in 0.001 in steps. Two notes on the manual itself. In the second example the required pallet is printed as 00.95 in, which the arithmetic and the first example both show should be 0.095 in, so it is a transposed nought. And the camshaft must be aligned before the head goes on, the line on the camshaft flange against the groove in the front bearing cap, which is number two cylinder at top dead centre firing; the manual warns twice, in capitals, that getting this wrong bends valves or pistons. Source: Repair Operation Manual Section 12.29.48, read at source.
Oil pressure
| Specification | Figure | Notes |
|---|---|---|
| Running pressure | Approximately 40 psi (2.8 kg/cm²) at 1,000 rpm | Repair Operation Manual Section 12, Lubrication System |
| Relief valve opens | Approximately 50 psi (3.6 kg/cm²) | In the oil pump itself, which is an eccentric rotor type driven by the jackshaft |
| Warning light extinguishes | 3 to 5 lb/in² (0.21 to 0.35 kg/cm²) | Factory General Specification Data |
The warning light figure is the one worth carrying in your head. The light goes out at three to five pounds, which is roughly a tenth of normal running pressure, so a Stag with a lit oil light has almost no pressure at all rather than merely low pressure. It is a catastrophe warning, not a low-pressure warning, and the moment it lights the engine should be stopped rather than nursed.
Transmission
| Specification | Figure | Notes |
|---|---|---|
| Manual gearbox | 4-speed, synchromesh on all forward gears | |
| Manual gear ratios | 1st 2.995:1, 2nd 2.10:1, 3rd 1.386:1, top 1.00:1 | Reverse 3.369:1 |
| Overdrive | 0.82:1 | Laycock, optional, operating on 3rd and top |
| Automatic gearbox | Borg-Warner Type 35, 3-speed (option) | 1st 2.39:1, 2nd 1.45:1, 3rd 1.00:1, reverse 2.09:1 |
| Final drive | 3.7:1 (37:10) | Hypoid bevel |
| Drive | Rear-wheel drive |
Reverse gear is given as 3.369:1 in workshop-manual data and as 3.609:1 in one period reference; the former is used here.
Capacities
| Specification | Figure | Notes |
|---|---|---|
| Cooling system, with heater | 18.5 pints (22.3 US pints, 10.5 litres) | |
| Engine sump, drain and refill | 8 pints (9.6 US pints, 4.5 litres) | |
| Engine sump, drain and refill with filter change | 9 pints (10.9 US pints, 5.1 litres) | |
| Oil filter | 1 pint (1.2 US pints, 0.56 litre) | |
| Gearbox, from dry | 2.25 pints (2.7 US pints, 1.28 litres) | |
| Gearbox and overdrive, from dry | 3.75 pints (4.5 US pints, 2.13 litres) | This is the A type. Rimmer Bros gives 3.5 pints (2.0 litres) for the J type |
| Automatic transmission | 11.5 pints (13.9 US pints, 6.5 litres) | The factory figure, given without qualification. Rimmer Bros gives, from dry and including the oil cooler, 14.25 imperial pints for the Borg-Warner Type 35 and 9.5 imperial pints for the Type 65. These are probably measuring different things rather than disagreeing, and both are given rather than one chosen |
| Rear axle, from dry | 2 pints (2.4 US pints, 1.13 litres) | |
| Power steering reservoir | 1.25 pints (1.5 US pints, 0.7 litre) | |
| Fuel tank | 14 imp gal (16.9 US gal, 63.5 litres) | Early right hand drive cars. From 1973, and on 1972 left hand drive cars, 12.75 imperial gallons (58.0 litres). Source: Rimmer Bros |
These come from the Repair Operation Manual Section 04 General Specification Data, which is itself headed as applying to early cars. Treat them as the early-car figures and check anything critical against the manual for your own engine number and market.
Chassis & running gear
| Specification | Figure | Notes |
|---|---|---|
| Floorpan lineage | Derived from the Triumph 2000 saloon | |
| Body style | Four-seat convertible with fixed T-bar roll hoop | |
| Front suspension | Independent, strut type, coil springs | |
| Rear suspension | Independent, semi-trailing arms, coil springs, telescopic dampers | |
| Brakes | Discs front, drums rear, servo-assisted | |
| Steering | Rack and pinion, power-assisted | |
| Tyres | 185 HR-14, or 185/70 HR-14 | 26 psi front, 30 psi rear, cold |
Suspension, brake and steering types agree with the archive's own Suspension & Steering and Brakes guides.
Performance
A named period road test is now available: Motor Sport tested the Stag in October 1970. The figures below are taken from that test. The spread in published figures, 113 to 117 mph and roughly 9.5 to 11.6 seconds for 0 to 60 mph, still matters because not every source states which transmission was fitted or which market the car served. Where a figure cannot be attributed, it is given as a range rather than a single number.
| Specification | Figure | Notes |
|---|---|---|
| Top speed | 117 mph | Motor Sport road test, October 1970. The same test gives the Stag's best one-way speed as 119 mph and the mean as 117 mph. |
| 0 to 60 mph | 10.7 seconds | Motor Sport road test, October 1970. |
| Factory claimed 0 to 60 mph | 9.5 seconds | Triumph publicity figure, not independently tested by this archive. |
| Published top speed range | 113 to 117 mph | The range reflects different tests and possibly different transmissions; not every source states which gearbox was fitted. |
Acceleration to 100 mph and standing quarter-mile figures are omitted because no attributed source has been found.
Dimensions & weight
The Stag sits on a shortened Triumph 2000 floorpan. Three different weight figures circulate for this car and they are not in conflict: they are dry weight, kerb weight, and kerb weight with the optional extras most cars actually carry. All three are given below rather than one being presented as the weight.
| Specification | Figure | Notes |
|---|---|---|
| Wheelbase | 100 in (2,540 mm) | Shortened Triumph 2000 floorpan |
| Overall length | 174.0 in (4,420 mm) | Some sources give 173 in (4,394 mm) |
| Overall width | 63.5 in (1,612 mm) | |
| Overall height | 49.5 in (1,258 mm) | With hard top fitted |
| Front track | 52.4 in (1,330 mm) | |
| Rear track | 52.8 in (1,342 mm) | |
| Turning circle | 34.1 ft (10.4 m) | Between walls. Single source |
| Fuel tank capacity | 14 imp gal (63.5 litres, 16.9 US gal) | Early right hand drive cars. From 1973, and on 1972 left hand drive cars, the tank is 12.75 imperial gallons (58.0 litres). Source: Rimmer Bros. |
| Dry weight | 2,646 lb (1,200 kg) | |
| Kerb weight | 2,800 to 2,811 lb (1,270 to 1,275 kg) | |
| Weight with optional extras | 2,970 lb (1,350 kg) | Hard top, overdrive and similar fitted |
Track figures vary between sources by up to 0.15 in. Overall length is the one dimension on which sources genuinely disagree.
Production
| Specification | Figure | Notes |
|---|---|---|
| Years of production | 1970 – 1977 | |
| Total built | 25,939 | |
| USA sales | 2,871 | Distributor figure documented by the Triumph Stag Club of the Americas. The 1974 and 1975 sales were remaining 1973 model-year stock |
| Estimated survival rate | ~46% | |
| Body | Speke, Liverpool (built, painted and trimmed) | |
| Assembly | Final assembly at Canley, Coventry |
The verified year-by-year USA sales figures and their source are published in the US Federal-spec guide.
Editorial policy: figures on this page are transcribed from documented sources, not rounded, estimated or reconstructed. They derive from the Triumph Repair Operation Manual by way of published transcriptions rather than from the manual in hand, and any owner with the original document is asked to correct anything that does not match. Missing rows will be filled in as sourced material is added to the archive.