primotipo…

HRH Prince Phillip during a ‘cooks tour’ of Coventry Climax Ltd, Widdrington Road, Coventry on 21 June 1966…

I tripped over these photographs searching for shots of the FWMV four-valve heads- that 1.5 litre V8 was the engine Jim Clark used to win his 1963 and 1965 F1 titles in the rear of Lotus 25 and 33 chassis, the second of his cups was won using the four-valver.

Unsuccessful as i was in my search for an image of one of the final iterations of this lauded engine, i did find this beauty of a ‘normal’ two valver with HRH alongside- who are the technicians exchanging cam timing details with the chief i wonder?

The one below of the Prince wandering towards the 1.5 litre, still-born, FWMW Flat-16 made me chuckle as it reminded me of a DC Nye anecdote which goes along the lines of the Climax hierachy showing off the ultimate expression of their design and precision engineering capabilities- which was singing its supreme song on the test bed, but conversation was impossible, so Climax Managing Director Leonard Lee instructed revs to be cut back- a fatal mistake as 5000rpm or more was needed, below that critical number savage torsional vibration caused the quill shaft to break with plentiful mechanical mayhem following shortly thereafter- which it did. Whilst not an engineer the royal understood that something was amiss, making soothing sounds of sympathy, he wandered further along the corridors.

Check out the engines below- FWMV show engine, FWMW 16 in the right foreground, an outboard to the left of Lee, but what is the Amal fed four in front of the Prince?

 

None of the four FWMW engines laid down ever found their way into the cars designed for them- oil drainage, pumping and windage losses and time pressures ensured that- the 1.5 litre formula ended and Climax decided not to continue in racing so the Lotus 39, Brabham BT19 and Cooper T80 never raced with the sixteen cylinder engine for which they were designed but with a 2.5 Climax FPF four, 3 litre Repco Brabham 620 V8 and 3 litre Maserati V12 instead.

Theoretical advantages of higher revs, greater piston area and better breathing of the sixteen were never realised, but that FWMV four valve V8 delivered the goods even if its advantage over its more conventional sibling was marginal, mind you, in 1.5 litres 5 bhp makes a difference particularly if Clark J was behind the wheel of the car to which said engine was fitted.

What a jewel of a thing and what might have been had the 1.5 litre formula lasted another year? FWMW 16 on the test bed in 1965.

The antecedent engine of the Flat-Sixteen conceived by Climax Technical Director Wally Hassan and Chief Designer Peter Windsor-Smith was the 38hp ‘Featherweight’ 1020cc, SOHC four- from little things do big things grow. The two men set about design and construction of a 1.5 litre, twin-cam, two-valve, fuel injected sixteen cylinder engine with central power take off with projected power of circa 240-250bhp @ 12,000rpm after extrapolating the power of the best of the FWMV’s to the greater piston area of their proposed new engine.

Whilst twelve and sixteen cylinder engines were considered, the sixteen modelled best using the bore/stroke ratio of the successful Mk3 FWMV of 0.76:1- this provided for a bore and stroke of 54.1mm by 40.64mm giving a piston area of 23cm. Using the previously achieved 4.5bhp per square inch of piston area gave the 250bhp projection.

Lets not forget competitive pressures were the cause of this exciting engine’s birth- both Ferrari and Honda were racing twelves which showed promise, but 1964 ended up a battle of V8’s- Ferrari, BRM and Coventry Climax of course, with John Surtees’ Ferrari 158 taking the titles by the narrowest of margins.

The design influence of the Ferrari Flat-12 engine showed in that Climax contemplated the motor being used as a stressed member so chassis mounting points for the combined crankcase and cylinder block were provided on the crankcase and heads, of which there were four- four sets of four cylinders.

The crankshaft had central take off to minimise the torsional vibrations of such a long piece of exotic metal- the crank was laid out as two, four-throw single plane-units running in five main bearings but turned through 90 degrees to each other with their inner ends shrunk onto a central spur-gear. The spur gear passed power to an output shaft running below the crank at 80% of engine speed to suit the gearing of the ZF and Hewland transmissions used contemporarily.

 

The heads, as described above, used two valves and a single plug- the included angle between the valves was 48 degrees with inlet tracts designed for the port type Lucas fuel injection with which the designers were well familiar- Lucas also provided the transistorised ignition system.

Trains of spur gears running off the central power takeoff drove oil pressure and scavenge pumps down below and and the twin overhead camshafts and auxiliaries above the takeoff. Auxiliaries were located outta the way atop the crankcase comprised twin fuel injection pumps, the distributors and alternator- whilst the motor sounds huge it was small- only one inch longer than the FWMV at 30.9 inches and 22.6 inches wide.

Design commenced in 1963 with the first run on the dyno in late 1964- the major problem, as Prince Phillip will attest, was severe torsional vibration at low revs. A stronger replacement took too long and also failed- the best seen on test was 209bhp, none of the problems were insurmountable but the 1965 season was underway with developments of the good ole FWMV good enough to do the job.

Richie Ginther’s Honda RA272 V12 win at Mexico City in the very last Grand Prix of the marvellous 1.5 litre Formula in late October 1965 was perhaps a portent of what may have been an amazing battle between the Ferrari and Honda twelves and Climax sixteen in 1966 had the Formula run one more year, ignoring the small matter of Climax’ withdrawal from racing of course…

Etcetera…

Further research- not exactly the shot of the heads I was after but a great view of the four-valver’s camshafts, plugs and gear driven cams which were characteristic of this Mk6 engine used by Clark and the Mk7 allocated to the Brabham Racing Organisation- the two only 1.5 litre FWMV four valve engines.

The mechanic (who is it folks?) got the Lotus 33 back together in time for Jim to win the Dutch Grand Prix the following July 1965 day from Jackie Stewart’s BRM P261 and Dan Gurney’s Brabham BT11 Climax.

Denis Jenkinson eliciting information on the specification of the three Lotus 33’s at Spa in June 1965.

The #17 machine is Jim’s race car fitted with the four-valve engine- note the low level exhausts fitted to his two cars whereas the #18 Mike Spence 33 has a much earlier spec Climax fitted with two-plane crank and crossover exhaust.

Jim won come raceday from Stewart and McLaren’s Cooper T77 Climax with Mike seventh on a circuit where the extra 10bhp or so would have made a hellluva difference.

Still in the Spa paddock, note the distinctive ribbing on the cam covers of the four valve engine compared with the two valve motor shown in the drawing below. Low level exhausts, Lucas fuel injection- output of this FWMV Mk6 was quoted as 212bhp @ 10,300rpm and 119 lb/ft of torque at 8,900rpm.

ZF five speed transaxle, rubber donuts at the driveshaft inner ends, outboard non-ventilated disc brakes and rear suspension comprising single top link, inverted lower wishbone, two radius rods, coil spring/damper unit and magnesium upright- period typical and oh-so-effective, the rear end bite, traction of the 25/33’s was said to be one of the performance differentiators compared with the BRM P261.

Credits…

Getty Images, Doug Nye, M Hewitt, MotorSport, Vic Berris, Coventry Climax, ‘1 1/2 Litre Grand Prix Racing: Low Power, High Tech’ Mark Whitelock

Tailpiece…

A capable pilot, Prince Phillip about to leave Coventry, no doubt he had promised the Queen he would be back in London before afternoon tea- Westland Wessex ‘chopper?

Finito…