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Ducati Test |
History on Wheels (page 2) Ducati didn't actually have a Reparto Corse in the factory back then, so both machines were in fact constructed in the Scuderia NCR race shop, a long stone's throw outside the Bologna factory front gate, as modified versions of the NCR900 Endurance racers, complete with special, sand-cast, old-style round-case crankcases, one of 20 such pairs made with internal stiffening webs, as then permitted under F1 rules. These were also modified to accept a Pantah-style screw-in oil filter, and fitted with a close-ratio gearbox and all-metal dry clutch, with magnesium outer cover. But on receipt of the bikes late in '77, Wynne followed what was by now standard practice and dismantled them both to the last nut and bolt, before rebuilding them to TT1 specification, with many modifications. These include boring out the beautifully-polished standard rods and flywheel webs to accept a larger diameter crankpin and oversize rollers, to overcome what had repeatedly proved to be the engine's achilles heel: rev a bevel-drive Ducati big twin much over 8000 rpm on a standard big end, and you'll shorten its life drastically. Next, the 86mm bore NCR pistons were junked in favour of a set of 87mm American-made Venolias, obtained from Cook Neilson who earlier in 1977 had scored a landmark victory in the Daytona Superbike race over the Japanese multis, riding his 'California Hot Rod' desmo V-twin. These Teflon-coated pistons give increased 11:1 compression and are much stronger than the NCR parts, as well as delivering a slightly larger engine capacity of 883 cc. After rebalancing, these mods ensured the engine would be reliable up to 9500 rpm - though Mike claimed to have used 1000 revs more in his epic Post-TT Mallory Park race, where he once again took on and defeated the best of the four-cylinder Japanese opposition on a track much more suited to them than the long, lean, lazy-revving Ducati. With peak horsepower of 87 bhp at the rear wheel at 9000 rpm on the Sports dyno, it was an impressive testament to the value of desmo valve gear, as well as Steve Wynne's engine preparation, that nothing ever broke on the bike in all the miles Mike covered on it....
This horsepower is delivered with the help of flowed, ported 60-degree factory cylinder heads (stock bevel-drive Ducati heads have a 72-degree valve angle), fitted with oversize 43.5 mm inlet valves (compared to 39 mm on a stock 900SS) and 39.5 mm exhausts (36 mm standard), plus 'Super-Imola' factory camshafts giving 12.5 mm lift on the inlets - though Wynne added extra keyways in the bevel gears to vary the valve timing at choice. He also fitted a Lucas Rita electronic ignition to overcome the notoriously fickle nature of Italian electrics, running 36 degrees of advance at 6000 rpm, while standard PHM40 Dell'Orto pumper road carbs are employed, as then required under TT1 rules, but with about half the plastic bellmouth cut away to obtain optimum intake length, and the accelerator jets removed, to deliver smoother running at part-throttle openings such as are commonly used in the Isle of Man. And after Roger Nicholls lunched the clutch on the startline of the Brands Hatch international in October '77, soon after Sports got the bikes from Italy, the clutch springs were replaced with 450 single-cylinder components, and the three backlash dogs on fourth gear ground away to overcome the perennial Ducati problem of jumping out of gear. That didn't cure it, though, so using Mike Hailwood's connections with F1 racing car gearbox specialists Hewland Gears, a complete new close-ratio gear cluster was manufactured incorporating many detail improvements, which proved trouble-free thereafter and is still in the bike today. * * * * * |
