MOTORS AND MOTORING

Dominion, Volume 11, Issue 174, 12 April 1918, Page 11

MOTORS AND MOTORING

(By "Clutch.")

The Radial Engine

Discussing; the prospects of the rudial engine ft prominent English writer on light-car topics states:—"Mysuggestion that an air-cooled radinl engine may prove to be the iwwer unit of the future'for-light ana medium cars has roused some discussion, and on the Thole'the verdicts aro favourable.- The main criticisms relate to ground clearance, and this.objection is probably ■ decisive eo far as either very high horse powers or very long piston strokes are concerned. High horsepowers, can be obtained, however, from quite a small radial engine, owing to the multiplication of cylinders; thus a low or medium horse-power would be procured from, say, five cylinders, and an increase of over 60 per cent, in the h.p. would be'obtained-by adding four more cylinders without any porceptible increase in the overall diameter. Tho diameter of an ovorhead-yalved radial engine is usually about eight times tho piston- stroke, so that an engine of 75 mm. stroke would measure about 3ft, in diameter —a dimension which presents no difficulties at all—and would deliver up to 40 h.p. for a nine-cylinder. ■ The above stroice-diamoter ratio would be slightly.reduced if side ivalves were fitted; but engineers will not be keen on side valves after tho war. A slightly impro.ved ground clearance is possible if the number of cylinders be reduced; thus a three-cylinder in the form of an inverted Y economiEes t several inches, and a five-cylinder frith a "flat" at its base is slightly lower than a nine-cylinder. Cooling presents no difficulties at all; the balance is magnificent;' and the engine will throttle down to a very low rate of r.p.m." A Sooted Plug. Incipient misfiring generally is due t<) a sooted plug, says tho "Motor Cycle." No experienced rider ever

stops his engine and gets out his spanners, until he has. first tried whether sin instantaneous no-trouble euro will work; and as this , cure is almost equally applicable tP minor carburrettor troubles, its value is sufficiently apparent. The moment misfiring begins, and before, the miss has a chance to stop the engine, throw out the clutch and open the throttle, allowing tho engine to race madly for sixty seconds or so. As a rule, this simple expedient will cure the misfiring. Hers and There. . Occasionally, says an exchange, we hear af a\raotor*car engine that apparently has lost EiMio of its power, and will not respond to tho throttle movement as it formerly did, notwithstanding certain adjustments, such as cleansing of 'the carburettors and eparking plugs, and so forth. In several cases tho causo has been placed to undue wear at tho tappets, and when readjusted the sluggishness disappeared. The average amount of tappet clearance is small—on light-car engines eightthousandth's to ten-thousandths of an •inch—the distance being measured by a feeler gauge, which consists of a number of metal strips each of.a different thickness, arid fitted to a handle like a pocket-knife. Each blade is numbered, and the largest .that can just be inserted between the valve- and the tappet when tho valve is down represents tho clearance. It is very necessary to ascertain that tho valve is down end on its seat before making tho adjustment, otherwise the work may have to bo done over again,

When brakes of. tho usual type, as fitted to automobiles, and operating on tho drums of tho rear wheels, do not perform their function satisfactorily, somotimes holding, sometimes not, it possibly, is duo to tbo presence of grease on the drums; and it is also very probable that tho actuating rods and levers ne«d adjusting. If brakes net on one wheel and not on the other, or if the car evinces a tendency to swerve- when tho brakes are applied, it is evident that the compensating device or equalisor needs attention. If tho brakes aro of tho metal to metal typo they may need renowal; othcrwiso tho linings may bo worn. Tho brakes should bo periodically examined to mako sure they aro entirely out of action when released. Lighting-lip time:—To-day, 5.27 p.m. Next Friday, 5.16 p.m.