THE 6-CYLINDER FRAZER NASH.
A NEW MODEL OF DISTINCTIVE CHARACTERISTICS.
A8 exclusively reported in the columns of MOTOR SPORT some months ago, Messrs. A.F.N., the manufacturers of Frazer Nash cars, are producing a six cylinder model, and the first batch of engines have already been delivered. One of the first cars, driven by Mr. C. M. Needham, won its class at Shelsley some weeks ago. The one we tried was the first ever produced, and was handed over perhaps a little unwillingly, as it embodied various experiments in the way of springing and other matters which will be altered in later cars of the same batch, but even
without making allowances for this, the makers are to be congratulated on a thoroughly successful model. One’s first impressions were that none of the brisk acceler
ation which is the most conspicuous feature of Nashes had been lost, but that the sturdy punch of the four had been replaced by a smoothness w h ich made driving a real pleasure. The exhaust note was subdued, by the addition of a Derrington silencer to the standard arrangement, and altogether the stage was set for fast driving without giving offence. A rev, counter had not yet been installed, but the comfortable speed in the gears were found to be 32, 54 and 77 m.p.h., giving an engine speed of about 4,400 r.p.m. in each case. Changing into top did not bring about much increase in speed, being Just under 82 m.p.h. for a timed half mile. The reason for this was because of the high top gear, 3.8, fitted as an experiment. The revs, with this gear were only were about 3,700, which won Id reduce the Power available by about 17%. By fitting a 4.1 top, and this the Prater Nash
chain final drive allows without altering the other ratios, one would expect the revs, to increase to about 4,500, giving a maximum speed of 90.
The acceleration figures up to 75 m.p.h., except those from 10-20, which are adversely affected by the high bottom gear, are better than those of any unsupercharged car tested in MOTOR SPORT since acceleration curves have been published This is due partly to the good powerWeight ratio, and partly to the almost instantaneous gear-change. The braking distance from 40 m.p.h. IS 72 feet, which is not up to the usual standard of sports cars. More power might have been obtained by stronger application in the front. However bard
they were applied, the car showed no tendency to swerve. The six-cylinder engine is fitted into the long chassis, but in spite of this, the new model corners in the same spirited fashion as the shorter cars. Ordinary corners can be taken very rapidly without the slightest trace of sway, and if one finds that it it sharper than one expected, the steering can be locked over and the tail slid round till the front of the car points in the required direction. This manoeuvre is much aided, of course, by the high-geared steering, which also has a strong caster action, one of the distinctive features of Frazer Nash cars. It certainly requires a little more effort than the low-geared variety, but this is more than repaid by the speed with which
emergencies of trials or racing can be dealt with. The road-holding, both on the road and the track, was entirely satisfactory, but the rear springing proved rather harsh on one or two occasions. This will be remedied by fitting a different type of spring.
The gear change, which is effected by sliding dogs, is easy and rapid, almost as quick as with a selfchanging gear box. The clutch was smooth, and frees with less effort than of yore, and the reverse stop is released by lifting a catch on the lever, an improvement on the old system of lifting a knob on the floor. A racing hand-brake, the ratchet of which is only engaged when the knob is depressed, is another good feature. The simplicity of the gear-change and the rapid speeding up of the makes
of the engine makes fast driving seem a commonplace thing, acceleration being carried out on the three lower gears with top as a quiet and econimical cruising gear when the required speed has been attained. As most Frazer Nash owners demand maximum performance throughout the range, however, it has been decided to fit a 4.1 top gear, as suggested earlier in the article.
The last part of our test was cut short somewhat by persistent sooting of the plugs. This was traced to flooding caused by excessive pressure in the petrol tank, pumped up but not recorded by a faulty gauge. Truly an obscure fault and one which only occurs once in a thousand times. Before this occurred, sufficient mileage had been covered to show that The makers have successfully combined the performance of the four cylinder models with
the refinement and even torque only possible with a six.
The power-unit of the new car is a six-cylinder specially made to Frazer Nash specification by the Blackburne Engineering Company. The bore and stroke are respectively 57 and 97.9 mm., giving a capacity of 1,498 c.c., with an R.A.C. rating of 12 h.p. One of the overhead camshafts is driven by a double roller chain from the rear end of the crankshaft, where it is not affected by torsional oscillations, and the other camshaft is driven from it by skew-teeth pinions. The valves, two per cylinder, are inclined to one another at 90 degrees, and are operated by rockers, with a roller at one end and an adjusting screw at the other. A 14 mm. plug is set vertically in the middle of each head, and they are thus very accessible. So also is the large oil-filler which is carried on the rockercover.
The block and the cylinder head are of cast iron, with an aluminium crank-case and sump. The latter is ribbed and holds two gallons of oil.
The crank-shaft is balanced and is carried in three plain and two roller bearings the latter being at each end. A torsion damper is mounted at the front end. Pistons and rods are of RR. 55 alloy, with plain big-ends. Three carburettors, either Zeniths or S.U.s are mounted on the near side of the engine, and are supplied by S.U. petrol pumps or by pressure, whichever is specified. The exhaust ports are on the other side of the engine, and the pipe is taken away at the front end. A dynamo and water pump are driven in tandem on the off side of the engine, and also the Bosch distributor with its two contact breakers, a feature which is said to prevent
the falling off of the spark which is liable to occur with coil ignition at high speeds.
The engines develop 75 h.p. and are mounted on Silentbloc bushes at their centre of gravity, which minimises the transmission of oscillations to the chassis.
The transmission follows usual Frazer Nash lines. A single plate clutch is fitted, and a propeller shaft with one universal joint drives a cross-shaft throdgh spiral bevel gears. On this cross shaft are mounted four sprockets, with corresponding ones on the solid rear axle. Any of these can be locked in turn giving a direct drive through roller chains. They are lubricated by means of a hand pump.
Quarter-elliptic springs are used back and front, the shock-absorbers being used as radius rods in front. The front axle is tubular, and cable operated. 12 inch brakes are fitted.
The chassis is the same size as the standard long chassis, but the side members are heavier, and there is an extra cross-member in front. Another alteration from standard is the 13i gallon rear tank. The chassis weight is 181 cwts., with tanks, including the auxiliary ones on the dash full.
Any bodywork can be fitted to order, but the car we tested was fitted with a workmanlike body on the lines of the fourcylinder cars, the bonnet of course being longer. It seemed very solidly constructed and was free from squeaks or rattles, and allowed 5 good view of the front wings.
The chassis complete costs 2575, and the makers’ address is A.F.N. Ltd., Falcon Works, Isleworth, Middlesex.
T. G. M.
Acceleration chart of the 6-cylinder Frazer iNiash.