A tale of two Triumphs

(With partial apologies to Charles Dickens)

The Editor tries the new 2500 TC and comments further on the popular Dolomite Sprint.

As Motor Sport announced in June, a new big Triumph, coming between the 2000 and the 2.5PI, has been introduced and when, having written that “Buy British” Editorial, I suggested to British Leyland that it was about time I drove some British cars, this 2500TC Mk. II Triumph was the first one they produced.

It can be rated a very nice touring saloon but in no way a sporting proposition. It costs £2,326 with the optional power steering and overdrive. The twin-SU six-cylinder push-rod engine gives 99 (DIN) b.h.p. and runs smoothly and quietly unless you ask it to turn fast, when its antiquated long stroke is betrayed (75 x 95 mm.). Such modest power, developed at 4,700 r.p.m., further emphasises the out-datedness of the power unit, and it brings rather mediocre urge, such as a top speed of 103 m.p.h. (but 90 in o/d third) and 0-60 m.p.h. acceleration taking more than 11 seconds. The gear change is somewhat notchy and has long movements but o/d is conveniently selected from a slide on the gear-lever knob. The minor controls and instruments are well conceived, with two stalk-levers, and the warning lights in a circular cluster. The seats are big and comfortable, the boot large and unobstructed, and those who like old-fashioned amenities and arrangements will welcome the manual choke, openable 1/4-windows in the front doors and the real wood facia, with lockable cubby, and the matching window cappings. There is very thorough and powerful heating and ventilation but no tachometer or oil-gauge is fitted.

The rack-and-pinion power steering is high geared (3-turns, lock-to-lock) and this Triumph 2500TC is a restful car for fast cruising. Its handling is, however, not altogether impressive, and I consider that Ford, with the Consul 2500, have it licked. But Triumph fans will like it and it follows so closely the former concept that there is no need for a detailed description. As for economy, driving largely in o/d I got 29 m.p.g. of 4-star but harder driving reduces this to around 24 m.p.g., and the 14-gallon tank ensures a useful range. No oil was used in 600 miles. The servo disc/drum brakes were rather heavier to apply than expected but satisfactory, a wheel-trim rattled on rough going, I disliked a notice which told me to fasten the safety-belts, the door-locks were stiff to operate, and a Dunlop SP68 tubeless tyre slowly deflated. A comfortable saloon this, which however, did nothing for me except transport me sedately wherever I had to go.

***

Having greatly enjoyed the Triumph Dolomite Sprint when it was newly announced, I was glad that BL agreed to let me re-cap on it.

Before doing so, however, there is that misleading advertisement to be disposed of. It appeared in The Times on June 7th, and was headed “The Design Council Award has gone to our head”. It was issued to proclaim the good news that a Design Council Award has been made in respect of the Dolomite Sprint’s ingenious valve gear for its sixteen-valve cylinder head. It is excellent that this neat piece of design work led by Spen King has been officially recognised. But unfortunately in underlining this the copy-writers went badly off the rails. For in saying that 16-valve engines (they mean for four-cylinder power units) “have been around the racing circuits for years and are fine for power” they implied that these were all twin-cam engines which they labelled as “noisy, fussy and temperamental”. They embellished this by remarking that these problems “still show themselves in many expensive twin-camshaft high performance saloon cars….” Apart from this remarkable mis-statement in a full-page The Times advertisement being rather unkind to another Coventry-built car, the XJ6 Jaguar, it becomes nonsensical by saying that “the complicated twin-camshaft configuration” was “hitherto essential to sixteen-valve engines”. What nonsense! The Triumph copy-writers have conveniently overlooked such classic single-cam multi-valve engines as the Bentleys of W.O. Bentley, the Brescia Bugatti of Ettore Bugatti, the sports Sunbeam of Louis Coatalen, not to mention the 2-litre and 3-litre Bignan production power units. In stating that 16-valve racing engines invariably had twin-cam valve-gear, the Triumph publicity chaps have conveniently overlooked one of the most successful single-o.h.c. multi-valve racing cars of all time, namely the Mercedes that finished first, second and third in the 1914 French GP. They have also forgotten, if they ever knew of them, those single-cam 16-valve racing engines by Nazzaro, Opel, Fiat, Rolland-Pilain, Sizaire, and AC. (A table in Pomeroy’s “Grand Prix Car” repeated in Court’s “Power and Glory,” attributes this valve gear to the 1914 Coupe de L’Auto Peugeots but, in fact, these had twin-cam engines.)

What Triumph have done in the Sprint engine is to actuate the eight inlet valves efficiently by prodding them directly from the single 8-lobe o.h. camshaft, at the cost of using eight rather long rockers to actuate the eight exhaust valves. Is this such a simple solution as it sounds ? Some of the early sixteen-valve single-o.h.c. 4-cylinder engines had 16-lobe camshafts and 16 rockers, examples being the sports Sunbeam which employed 16 short bell-crank rockers, and the Brescia Bugatti in which 16 non-pivoted lightweight sliding “banana” tappets replaced the conventional rockers. But the original 3-litre Bentley engine had just an 8-lobe camshaft and eight forked rockers, like the Dolomite Sprint, but with shorter rocker gear. In production form it and the 4-1/2 — litre Bentley used a 12-lobe camshaft, with separate rockers for the exhaust valves and shorter double-arm rockers for the inlet valves, or a total of 12 rockers, the layout adopted for the all-conquering 1914 GP Mercedes. So all the Sprint can really claim is to have eliminated four or eight of the rockers normally found in a four-cylinder sixteen-valve single o.h.c. power unit by the substitution of abnormally long exhaust rockers. It can hardly claim many marks for its direct actuation of eight of the valves, a la HispanoSuiza, when this classic layout is not used for its remaining eight valves! Anthony Blight will say it’s all poppycock anyway, as they would have done better to have copied Georges Roesch’s simple lightweight push-rod system.

I wonder therefore whether another full page advertisement will now appear in The Times, apologising to earlier designers of single o.h.c. multi-valve engines, the late W.O. Bentley in particular ? Misleading as this advertisement is on technical grounds, do not let it put you off the excellent Triumph Dolomite Sprint or, for that matter, 16-valve engines. It is worth recalling that in their beautiful catalogues (now another collectors’ item!) the old Bentley Company used to claim that the use of four valves per cylinder not only improved the breathing of their engine but increased its reliability, “The seating area is increased by 50% and in consequence the cooling surface is greater, and a greater volume of water can be circulated through the space surrounding the seatings. Further, the hammering effect on the seating of a single large valve with a strong spring is greatly diminished by using two light valves with light springs,” they claimed. Realising that there were twice as many valves to grind-in, they hastily added that this chore should not be required until the car had done 20,000 miles!

Well, today you don’t grind-in your valves, so Spen King has all the advantages on his side. I think it is probable that when Henry (or Birkigt?) designed the 1912 GP Peugeot engine with four valves per cylinder and is reported as saying he did this, not to improve gas flow or to reduce valve inertia, but simply to have a standby in case of failure of one of the valves, he may have been misquoted and that what he was aiming at was reducing the likelihood of valve trouble, for the reasons given in the old Bentley catalogues. However, gas flow is improved, as Bentley knew, by doubling-up the number of valves, unless a wide-angle, hemi-head arrangement is employed, and this the Sprint engine does not have, as its unique layout would then require even longer rockers. Having disposed of all this, I was looking forward to that promised re-cap on what a nice car the Dolomite Sprint is to drive. Alas, it was not to be. Having dutifully returned the 2500TC, I was told that the Sprint would not be arriving, because there was an industrial dispute at the factory and Triumph could not take out their own cars. So much for trying to persuade you to Buy British by writing road-test reports on cars made in Coventry! (At the same time a colleague was informed that the Reliant Scimitar booked for test weeks ago would not be delivered, because repairs had not been completed.) Never mind! For some time while doing tests of other cars I had been finding myself praying something on the lines of “Oh, St. Christopher, I beseech thee, restore unto me mine BMW, that I may dwell not too long among the red lights, and that peace and tranquillity may bless my rapid passage through the land”. And lo, it was so. The 520i was in the office car-park and I was able to go home in it. Time, I guess, to be signing off ! –WB

That misleading Triumph advertisement: