Mk I and Mk II Stags
– the difference
The Triumph Stag came into production in June 1970 and retained its basic concept until final production in June 1977. There are two basic models, ie Mk I and Mk II, the Mk II being introduced in February 1973, the basic changes being: The first thousand or so cars that were made had single points in the distributor which was later changed for dual points.
On the warning light cluster, there is a temperature warning light which is triggered by a switch on the offside cylinder head. This proved to be so inaccurate that it was discontinued on later models. A factory modification was circulated to British Leyland dealers to cut back the wire from the switch so as to make the light inoperative.
The next change came in early 1972 – the water system was redesigned although the waterways within the engine were left unaltered. Externally, the radiator is now a sealed unit with an expansion tank now running at 20lb instead of 13lb. A ‘U’ hose connects the rear of the thermostat housing to the water pump housing. Previously there was a three way union connecting it to the heater rail. At the same time the air filter box was redesigned and now draws in cold air from above the radiator and hot air from the near side exhaust manifold. A heat sensitive vacuum control flap decides whether to select hot or cold air. At this time a chrome moulding was fitted to the sill panels. When the Mk II model was introduced, the only change in the engine was that the combustion chamber was reshaped and the pistons now have a dome on top. The manual with overdrive was now standard using a ‘J’ type overdrive instead of the ‘A’ type as used in the Mk I car. Tinted windows were now standard along with a laminated windscreen.
The side windows were removed from the soft top and mohair material with a fawn lining was introduced, but not on the early Mk II, ie 1973 production. The background colour of the grille and rear quarter emblems was changed from silvergrey to black. The sill panels were matt black and the rear number plate panel was also matt black. The interior lights were removed from the door pillars to one single light in the centre of the roll-over bar.
interior trim was slightly redesigned and the front seats now incorporated fittings for head rests. Instruments had chrome lip to bezel, and the fascia was redesigned. A smaller diameter steering wheel was fitted, and twin coachlines were introduced. In 1974 seat belt warning lights and hazard warning lights were introduced. 1975, air conditioning became no longer available, and tufted carpets were fitted. Brushed aluminium sill plates were fitted in 1976 and alloy wheels became standard. The number plate panel went back to the body colour. The handbrake lever grip was redesigned, and a push button reset trip-on speedo was introduced. In 1977 the auto gearbox was changed from the Borg Warner 35 to the Borg Warner 65. Rubber inserts were fitted to the steering wheel spokes.
by Founder Member of the Stag Owners Club, Tony Hart