What became the troubled Triumph Stag started off as a simple request from Giovanni Michelotti to Triumph design chief Harry Webster.
Michelotti had strong links to Triumph and wanted a donor car for use in a new concept for the 1965 Turin show, so Webster sent him a Triumph 2000 sedan, previously used as a support car at LeMans.
The only condition was that if Triumph liked Michelotti’s concept, they’d have first refusal. As it turned out, Webster loved Michelotti’s sleek, clean convertible. It never even got to a motor show stand before Triumph decided to build it.
It was a fateful decision, because the Stag had a protracted development and an infamously troubled production life.
The Design Phase
Development on the Stag began in early 1966 and was part of an aggressive expansion plan, but by the time it reached the market in the fall of 1970, lots of things had changed became of the merger maelstrom sweeping the British motor industry. Leyland, which owned Standard-Triumph (by then the Standard name was retired) bought Rover in 1967, and a year later Leyland merged with British Motor Holdings into British Leyland.
In 1963 Triumph had started planning a new range of SOHC slant fours and V8s with common elements. The Stag was originally supposed to us the straight six from the 2500/2.5 sedans, but very quickly plans grew more ambitions and the “family” V8 would be used for a top model. The V8 might also be used in a “Triumph 3000” sedan, which would be a direct rival for the V8 Rover P6.
These new cars were a move upmarket for Triumph and, it was thought, might also have appeal in America. But it was not to be.
With the BL merger, Webster moved on to Austin-Morris, leaving Rover engineer Spen King managing the Stag. King felt the six wasn’t powerful enough, so the stag would be powered only by the Triumph V8, which took a long time (and lots of money) to fully design.
By then, Rover’s cars and V8 had been prioritized over any planned Triumph expansion – there wasn’t any need for a Triumph 3000 when the P6 was selling well and work was underway already to replace it. But the Stag didn’t get Rover’s V8 for a variety of reasons.
First, Triumph engineers just didn’t want to scrap the V8 they’d worked on in favor of a “rival” engine. Second, re-engineering for the Rover V8 might have added more delays to an already delayed car – engineers told Spen King, supposedly, that the Rover V8 wouldn’t fit.
It does, of course, fit – as many swaps prove. But as would be demonstrated on the MGB/GT V8, Rover’s V8 was also often in short supply. Triumph originally hoped to make 20,000 Stags a year – which probably wouldn’t have been possible with the Rover V8.
There’s also a persistent rumor that General Motors had a potential veto on uses of the V8 in cars destined for North America despite having sold it to Rover in 1965. The V8 did, in fact, come stateside in the Rover P6 and the brief appearance of the SD1 in the USA, but it may have been a factor in not using it in the Stag – this rumor hasn’t ever been confirmed or denied.
The Stag Arrives
When it finally arrived in the summer of 1970s, the Stag’s muscle-car looks belied a relaxed GT – complete with an optional Borg-Warner 35 Automatic for American tastes (or a manual with overdrive), but it was pretty and good to drive, if not particularly fast for a V8 car. A Ford Capri 3000 GT was faster, but the Stag looked and felt more exotic.
The Stag’s unusual “hoop” roof was the result of needing to make it rigid. This featured would turn up on many later convertibles, but was strange in 1970. Early roofless prototypes, which looked more like Michelotti’s original, were unacceptably shaky according to Webster, so the roof added structure and safety.
Unfortunately the V8 would prove the Stag’s undoing in the eyes of public perception. The high-mounted water pump meant poor coolant circulation in some circumstances. If the car overheated, the aluminum heads could warp and weren’t big enough to skim down. Too-long timing chains would develop tension problems and needed replacing after only 25,000 miles – on an interference engine. The Stag’s rep quickly soured.
The Stag was offered in the U.S. from the spring of 1971 until the summer of 1973, and just 2,871 were sold in the U.S. – it wasn’t a two-seat roadster and it was too small and too costly to be a rival to cars like the Dodge Challenger (in concept, it’s not so different).
At home, early sales were alright until quality ills and engine trouble started to become widely talked about. The Stag lingered in production until 1978, but BL’s lack of funds meant even though it was periodically updated in small ways, it could never be properly fixed. Low sales mean low investment.
Instead, it was left to enthusiasts and specialists to make the fixes that should’ve been worked out before the cars ever left the factory – Stags can be made to run properly and reliably, and many have been (though quite a few have swaps – Buick or Ford V6s, or Rover V8s, or in rare cases larger V8s).
Slight error/misunderstanding in para 8. When Spen JKing took over the decision to use the V8 in Stag had been taken. The confusion is that Spen took over a project with a 2.5l V8 as the power plant and that was deemed to be missing low end torque so it struggled to shift the heavy Stag from standstill. Spen increased the cubic capacity from 2.5 to 3.0l (and dropped the fuel injection idea as the engine couldn’t reliably satisfy the USA emission regs with the fuel injection system).
In the UK Stag sales were at a premium with waiting lists of over a year through to 1975 – but was in the States that tongues wagged excessively and there was a reason for that – to satisfy the emission regs, the compression ratio was reduced and the timing altered to suit. With the new timing spec, more heat was generated as combustion was tuned to low emissions not to maximum performance. That was why USA Stags suffered from overheating – especially on the West Coast – whereas in the UK the engine did not suffer the same overheating problems. They eventually started to suffer the erosion of cylinder heads and the silting up of radiators as garages used water instead of the correct anti-corrosion antifreeze – especially in summer when the change was ingrained into the UK psyche (heaven knows why, but it goes back to the days of the Austin 7 when you changed everything all the time). The silting up of water passages led to overheating and possibly to another dose if the garage just blamed ‘that bloody Stag engine’ without realising that the real culprit was the partially blocked radiator.
And, less than 10% of Stags ever got that replacement Buick/Rover engine – the presumption that the change was widespread is a fallacy, although the figures in the States were much higher as a percentage.