Tuning Minis

Press, Volume CVI, Issue 31123, 28 July 1966, Page 12

Tuning Minis

V STANDARD, off-the-shelf Austin Mini Cooper 1275 “S” is the “hottest" small, volume - production car currently made in Britain, but in the skilled hands of experts at B.M.C.’s special tuning department established to make the fruits of B.M.C. competition experience available to all enthusiasts—it becomes a world-class winner, says the Austin Distributors’ Federation.

For racing and rally drivers who could be interested in turning their Cooper “S” models into works-replica fireballs, the department recently revealed the “treatment” that was the background to Timo Makinen’s controversial win in this year’s Monte Carlo Rally. Makinen, who visited New Zealand late last year with his fellow B.M.C. driver Paddy Hopkirk, led the Mini-Coopers home in the 1966 Monte for the third year in succession, and the subsequent disqualification of the British cars is still the subject of appeals to the governing body of international motor sport. The main elements involved in transforming the stock 1275 “S”—capable of more than 95 m.p.h. in standard 75 b.h.p. trim —into a 105 b.h.p. racer are:

Four new hydrolastic units are fitted to stiffen the ride and make the car cling to the road more closely, and an oil cooler is fitted to keep the lubricants from thinning unduly under high operating temperatures. A tuned exhaust manifold drains fastmoving gases quickly, making sure there’s no final hindrance for the breathing systems

which starts with twin li inch S.U. carburettors, which are fitted with intake trumpets and special gaskets. Another special gasket goes under the cylinder head and raises compression slightly, but the main compression gain comes from a set of flattop pistons which are available in various degrees of over-size for those who are going to bore their engines out to the maximum of 1300 c.c.

Coupled with the piston set is a balanced crankshaft, flywheel and clutch assembly, allowing smooth, faster-than-norrnal rotation, for which the valves are equipped with double springs and a competition camshaft which gives increased valve - overlap and other power-producing benefits. A different dynamo pulley, fan belt and fan are needed —a bigger pulley is fitted to gear down the dynamo so it can cope with the extra revs, and a simple fourblade fan replaces the quieter, more complex standard 16blader.

In the transmission, straight-cut gears are fitted for strength, and a limitedslip differential stops wheelspin on acceleration and cornering. Replacement brake shoes and disc pads with competitions linings are needed, and while they call for higher pedal pressures they stop the Mini more quickly, more often. Finally a bonnet strap gives extra security in racing, and snap-on headlamp covers which keep lenses clean during daylight racing and prevent them from getting broken by stones.