New Zealand Notes
THE September, 1943, ” Bulletin ” of the New Zealand Sports and Racing Car Club contains information of more than usual interest. W. J. Farnsworth describes the Sunbeam cars he has had, comprising one of the 1912 “Coupe de l’Auto ” 3-litres, afterwards sold to another enthusiast who has rebuilt it, and a 1914 3.3-litre T.T. car and a “20/60 ” push-rod sports tourer, which he still possesses. The T.T. car, of which Anthony heal and Brodie Dunwell preserve examples in this country, is credited with 98 to 100 m.p.h. in touring trim, 0-00 m.p.h. in 9.2 secs., s.s. -mile in well under 20 sees., and 21-22 m.p.g. cruising at 2,000-2,500 r.p.m., equivalent to 60-75 M.p.h. A Smith 5-jet carburetter is used. Although not mentioned in the “Bulletin,” we believe Farnsworth is now on the scent of one of the 1921 straight-eight 3-litre racing Sunbeams, of which Heal preserves another Is) this country, and one of which was raced by Daybell at BrOoklands as late as 1930, afterwards becoming the Munday-Special (later Bainton-Special), with with a ” 30/98 ” Vauxhall engine installed. Another is owned by Burnand, with a Rolls-Royce ” Falcon ” engine in place of the original. Of Sunbeams in general, Farnsworth sagely observes that the ” 20/60 ” will probably prove to be more reliable, when
all is said and done, than a twin o.h.e. sports 3-litre, although he also seeks one of these. The push-rod car is at present slower, but he plans to reduce the weight considerably and to fit a higher axle ratio, of about 3.8 to 1 in place of the existing 4.7 to 1 axle, when he expects to get 90 m.p.h. at 4,000 r.p.m. He goes on to say that Sunbeam began to explore the luxury saloon class when Bentley was bringing out the 41-litre, and had given up interest in sports cars when Bentley was firmly established in that field. But he reminds his readers that no other firm, from Edwardian days to the turn of the quarter-century, did so much to further British racing prestige as Sunbeam, a banner handed on to Bentley and, in turn, to .M.G. The result is seen in every Sunbeam ever built, be it tourer, sports or saloon.
With experience of both, and an enormous regard for the Bentley, he admits : “I feel bound to say that, on the whole, I prefer the Sunbeam.” In the same issue of this “Bulletin ” is a long article on tuning for sprint events, by John McMillan. He emphasises the need for low head-resistance, even at speeds as low as 20 m.p.h., and prefers a fairly high e.g. for sprint work, to enable the weight of the car to assist adhesion
of the outer wheels on corners. A compression ratio of approximately 8 to 1 for cylinder bores up to 72 mm. and 7.-5 to 1 for larger engines, is recommended and honed or mirror-finished bores are to be avoided. A suggested valve timing is : inlet opens 200 before t.d.c., closes 70° after b.d.c. ; exhaust opens 70° before b.d.c. closes 35′ after t.d.c. Valve seats should, the author says, not exceed Au width for each inch of throat diameter. He finds Ford V8 valves, turned down to the required size, excellent, and believes in copper-plating the combustion spaces. Exhaust pipes should be the same size as the ports and of identical length, merging into a common pipe of slightly greater diameter. S.U. or Amal carburetters are recommended. With the recommended compressian ratios, it should be possible to use 80 octane fuel, but better results could be had from 50/50 petrol/benzoic—it is remarked that benzoic can be “bought quite cheaply from most gasworks ” I McMillan concludes by suggesting the following dopes : For b.m.e.p.. of 180-200 lb./sq. in., 60 per cent. methyl alcohol, 30 per cent. benzoic, 10 per cent. aviation petrol ; for b.e.m.p. up to 335 lb./sq. in., 50 per cent. Methanol, 20 per cent. Ethonol, 15 per cent. benzole, 12.5 per cent. petrol and 2.5 per cent. distilled water.