MOTORING WORLD

Manawatu Standard, Volume LIV, Issue 307, 24 November 1934, Page 12

MOTORING WORLD

NOTES. Tariffs on British motor-cars imported into the United States %vere lowered from 33 1-3 per cent, to between 10 per cent, and 25 per cent, according to classification on the signing recently of the reciprocal tariff bill by President Roosevelt. In view of the 25 per cent, reduction in horse-power tax which is promistd in England for January 1, 1935, British motorists will shortly take an increased interest in larger engines, which, in most cases, can be run with only a slight increase in the cost of fuel and oil. In normal service the alignment of front wheels should be checked after each 6000 miles. Bad alignment is a prolific cause of excessive tyre wear, and sometimes an unsuspected reason for difficulty in steering. Tyre pressures have a large bearing upon skidding; if they are very soft, there is a greater tendency to skid when cornering, particularly on a loose-surfaced road, although where the surfaces are slimy the reverse is rather the case, owing to the increased area in which the tread of the tyres makes contact with the road. USE OF BELT DRIVES. In the early days belt drives were somewhat troublesome; the belts used to break or slip badly and it was not possible to get any reliable form of power transmission in this way. Then manufacturers turned their attention to positive drives and the craze for these lasted for some years; manufacturers even went so far as to drive the fan positively. Now belts have greatly improved and 1931 saw the pendulum swing back to this form of drive. The modern belt is a very soundly constructed piece of w'ork which does not slip over the pulleys nor does it stretch unduly ; it will also convey considerable power for many months without attention or adjustment being necessary. Even when there is a certain amount of slack it will still continue to transmit power. A belt drive is generally quieter and smoother than a chain working over spockets; it acts also in the form, of a safety valve should a bearing seize, for example, in the dynamo through lack of lubrication. The belt in such circumstances would break or slip owing to the terrific load imposed upon it and no great harm would come' to the dynamo. With the positive drive, however, extensive mechanical trouble would follow in such circumstances. TAPPET ADJUSTMENT. The perfection of a process for lengthening valve stems in such a way that the fiddling task of tappet adjustment can be obviated is announced by an English concern. It comprises electrically welding new and very hard metal on the end of the stems. Introduced originally to make up the additional length of stem often needed after the valve seatings of an engine have been built up, the process is inexpensive, and valves so treated have run 15,000 miles and more w'ithout the clearances varying more than about two thousandths of an inch. Present-day cam contours favour the elimination of adjustable tappets because they are planned to permit tolerances as wide as plus and minus five-thousandths. If this system were utilised, car owners would not have to concern themselves with tappet adjustments in between the decarbonising operations, when grind-ing-in the valves would normally take up any wear that had occurred, and valves w’hich have worn too much for this could be lengthened and ground to the correct clearance.

ELIMINATING ENGINE FUMES

HINTS FOR THE DRIVER

Often when the engine becomes thoroughly heated during summer running a very unpleasant odour of fumes penetrates to the driving compartment and sometimes causes alarm because of the idea that it is attributable to an escape of exhaust gases. It is a good plan to look to the floor boards and front mat, and should there be wide gaps at the points where the pedal levers pass through the boards to tack on strips of felt or soft leather so as to seal the opening through which engine heat and oil vapours might pass.

As soon as any annoying symptoms are noticed the exhaust manifold and the joints in the exhaust pipe should be inspected for traces of leakage and if it is found that the exhaust is blowing past at any point, as revealed by a blackish mark on the surface of the piping, the joint should be packed or the gasket renewed. Frequently, however, a sickly smell of hot or frying oil is quite dissociated from any escape of fumes laden with carbon monoxide and arises merely from a dirty engine on which oil and dust have accumulated. If the cylinder block and crankcase are scrubbed with kerosene and then wiped clean the trouble will often disappear, but occasionally the source of the annoyance is more obscure. One driver who was perplexed because despite the cleanness of the engine an odour of burning oil persisted found that the fault was due to excessive greasing of the fan bearing, the surplus grease being thrown back by the fan on to the front end of the exhaust manifold. STICKING VALVES. When, because of an accumulation of gummy deposits on the stem, an engine valve sticks and refuses to close completely, the following expedient can be tried if the motorist is far removed from garage help and it is not found possible to loosen the valve satisfactorily.

A correspondent in an oversea technical journal states that he was in a quandary because an inlet valve had stuck open, and although it was prised several times so as to reseat it completely, the stem was so encrusted that the valve spring was not strong enough to close it. Had it been an exhaust valve it would have been possible to drive the vehicle slowly with one cylinder out of action, but the effect with an inlet valve was that the blow-hack into the induction manifold prevented the engine from running. The remedy adopted was to slacken the tappet adjustment so that there was a very wide clearance, the effect being that the valve then only half opened, and did not reach the top of its normal lift, at which point it jammed. Such a procedure, of course, caused painfully noisy running, but enabled the car to h 9 driven nearly 100 miles without damage or great loss of time.