Two sucessful specials
The Cooper-Daimler
The practice of using a V8 engine, other than a Formula One Climax or B.R.M. unit, has met with little success in this country, although the Americans have been using Buick-engined Scarabs, inspired cohsiderably by Cooper design techniques, for several seasons. The first really successful conversions to meet with any degree of reliability are the Cooper-Daimler, owned and driven by engineer Peter Westbury and Chris Summers’ Chevrolet-engined Cooper.
The Cooper Daimler started life as an early leaf-spring Formula Two car in the hands of Brian Naylor, who crashed the car badly and later disposed of it to John Campbell-Jones. Westbury acquired the car with a 1.5-litre Coventry-Climax engine, and sprinted it in this form for a season. Last winter a Daimler engine was acquired from the Coventry works and the two top tubes at the rear of the frame were cut to allow the 2.6-litre engine to be installed, The transmission was taken through a 1959 Cooper 4-speed gearbox with a 7¼-in. clutch, the engine and gearbox being mated by a simple aluminium adaptor plate. The cylinder heads were cleaned up by Barwell Engineering, who also fitted Jaguar 3.8 inlet valves. With the touring cam and twin S.U. carburetters maximum torque is obtained at 3,500 r.p.m., maximum power of approximately 160 b.h.p. is obtained at 5,800, while maximum revs have, on certain occasions, gone to 7,000 r.p.m.
Suspension has caused a little worry, especially at the front, although this has now been virtually ironed out, both front and rear transverse leaf-springs being replaced by more modern wishbone and damper units, the rear set-up comprising a single upper arm and a lower arm, actually being taken from an ex-Moss Cooper, made redundant after Moss changed to Lotus. Outboard disc brakes have been fitted all round.
This season, the first for Westbury as a contestant in the British Hill-Climb Championship, the car has beaten Fielding’s B.R.M. and Owen’s Cooper-Climax at Craigantlet, bettered Tony Marsh in the wet at Shelsley Walsh and provided Westbury with seventh place overall in the British Championship. Maintenance has cost very little, the Daimler engine proving extremely reliable, only the plugs being looked at as a cautionary measure and gearbox trouble on one occasion at Great Auclum has been the only real mishap so far. Next year a new chassis will be designed, using the V8 engine and the existing suspension; a Roots-type supercharger may be fitted if deemed necessary. The main purpose of the venture is purely as a hill-climb and sprint machine, specialising in short, sharp bursts where torque rather than top-end power is the deciding factor. — E. L. W.
The Cooper-Chevrolet
The Cooper-Chevrolet also started life as a leaf-spring Formula Two car, this being a 1958 car driven by Chris Summers as a Formula One car in 1961. The Chevrolet engine, a Rochester fuel-injection model, came from a 1958 Bel Air that B.P. Petroleum had been using for research purposes, the price for which was £75. Fitting of the 4.4-litre engine (it was enlarged later) was the task of John Farley, of Farley Special fame, and Chris Summers’ mechanic Jim Thornton, most of the work being carried out at the Thornton Heath workshops of Jack Newton.
Little has been clone to the engine, the main alteration being to bore the engine to 4.7-litres and fit American Jahns pistons, which John Farley turned down from 4 in. to 3 15/16 in. and finished off literally with a coarse file! The camshaft was changed for an Iskenderian roller-follower cam, and the heads were gas-flowed by Dan Richmond of Downton Engineering, who also fitted larger inlet valves and improved exhaust valves. The compression-ratio was increased from 9 to1 to 10 to 1, this increasing the power output from 255 b.h.p. at 5,000 r.p.m. to 320 b.h.p. at 6,000 r.p.m. The crankshaft has been untouched. The different camshaft has resulted in restricting the power band to 4,000 r.p.m. upwards, whereas before the power was obtainable all the way up.
The chassis has not had to be altered to take the engine, 1.5-litres coming out and 4.7 going back with room to spare! The rear track has been widened and the suspension has now been altered to all-round coil and wishbones, with disc brakes, twin radius arms being used at the rear. Transmission is through a 1958 Cooper 4-speed gearbox, modified by Jack Knight, power being transferred via a 7½-in. clutch plate. A ZF differential was not used for the first few races but was fitted subsequently. No modification has had to be done to the fuel-injection unit; the only malady encountered in thirteen events, of which the car has won seven, has been plug trouble on its first outing at the Easter Mallory Park meeting, where Summers was leading until retiring at about half distance. Of the other events entered, the Cooper-Chevy, as it is now called, has either gained second or third place, including two Championship second places at Shelsley Walsh. Again reliability has been achieved, only a new set of big-end shells being fitted in an entire season. Summers has lapped Snetterton at 102.9 m.p.h. and has also lowered the Silverstone Club Circuit record by two seconds. — E. L. W.