At the beginnig the Triumph engineers considered to drop the TR5 150 Hp Straight Six engine in, which was quickly cancelled, then, on a suitable purchase like the Daimler V8. But Chief engineer Harry Webster favored an own Lucas fuel injected Triumph V8, with 2500 ccm capacity, but by progressing the development, problems with the reliability of the Lucas Pi system in the 2,5 Pi Saloon and the TR5 Pi appeared.
But 1968 the British Leyland Group was formed, Harry Webster changed to Austin Morris and Spen King from Rover came to Triumph and the Fuel Injection was discarded in favor of a carburettor system, but such a prototype inlet manifold does still exist and is property of the British Motor Heritage.(see picture)
As Triumph was just developing a new 4 cylinder OHC engine for the new Dolomite Range and for the SAAB company, the engineers decided to double the slant 4 engine and ready was the 3 litre V8 lump.
The new, slant engines were of cast iron, the cylinder heads from alloy, the size was compact enough to fit perfectly in the Stag enginebay. The more, as the waterpump was situated inbetween the two banks, which made the enginge a bit shorter. The two overhead cams had cam followers and were operated directly by chains and sprockets, adjustments were made with shims.
The alignment of the cylinderhead studs and bolts were not parallel, the studs slightly slanted against the bolts.
The camshafts are driven by chains and 4 sprockets - 2 on the camshaft, one on the crank and one on the jackshaft, which drives also the waterpump as the distributor at the centre, rear of the engine.
The infamous cooling problems with its severe damages to the engine - lastly crucial for the Stag's bad reputation, its commercial flop and therefore withdrawl from the market, was an interconnection of single circumstances which led lastly to catastrophic results.
More under "Weakness"
After 40 years, many enthusiasts and specialists have driven the Stag and its engines whims out and and made him a remarakble classic today.
Der "Slant" 4 cylinde engine, from
which the V8 was developed.
V8 engine gearbox and overdrive
Original Triumph V8