THURSDAY, OCTOBER 15, 1931.
TUNING FOR SPEED
(Continued from Page 2.)
other.
The bevel gears must be meshed Regarding valves and their ad-
so as to avoid slackness on the one justment, with an over-head cam- shaft model the exhaust clearance hand and binding on the may be anything up to 20/1,000ths Overhead camshaft drive has many of an inch and the Inlet up to advantages, not the least of which 12/1,000ths of an inch. With push is that comparatively light valve rod engines there should be no per-springs can be used, as their only ceptible clearance allowed, the duty is to return the valve and "feel" of the push-rod being the beat rocker to its seating. This, of guide. With an overhead camshaft course means that there is less engine the clearance gets less as the stress on the valve gear, less wear engine becomes hot; the reverse and consequently less need applies with push-rod units.
AVOID SIDE PLAY
* LINKS ▼
SHOCK ABSORBERS
NOT TOO TIGHT
DAMPER NOT TOO FIGHTE
Points to observe' in con- nection with the front furks.
As to the valve seatings, do not make the exhaust seating too nar- row, as it is essential that the heat should be carried away as effective- ly as possible to the cylinder head. Mine are about 7/64ths of an inch cross. the valve diameter being approximately 11⁄2 in.
TD.C
for
THE
CHINA
MAIL.
provide for constant lubrication. At high-speeds 'n chain heats up fairly quickly and therefore must be kept well oiled.
For gearbox lubrication I use Mobiloil "TT"; In no circumstances should a heavy oil be used, as loss of power due to fluid friction must be reduced to the minimum..
I must lay stress on the need for absolute freeness of all parts as a tight spot may result in a seizure or at least absorba power which should be available at the rear
wheel.
Regarding chains, always use soft not the rivets to join the chain, usual type of spring clip, Clips are quite satisfactory for normal] use, but no risk should be taken. in
· really high-speed work.
Carburetter.
J
The chief duty of the carburetter is to provide for as great a volume
42° to 45°
&
Diagrammatic representation
ignition timing....
periodical adjustment. Personally, always, use standard springs in such engines.
Transmission.
RETARD
ADVANCE
of grs as may be demanded by the engine, a consideration so far as the engine is concerned which is governed by valve timing, port areas Induction and the nature of the
Guard against running on a weak! mixture, as this causes overheating, a fatal condition from all points of view.
Apart from making certain that passages. is In-so-far as the valve, gear concerned, see that the camshaft is driving sprockets are dead in line running freely. After cleaning in and that the chains are correctly benzole it should spin quite freely adjusted, there is very little to worry about. Regarding sprocket if in order. The skids or slippers adjustment, the eye is a fair test, should be absolutely dead square but the use of a straight-edge will with the cam-contour all round, failure to observe this, will mean ensure perfect results. The primary putting excessive stresses on the chain should have from 1 in. to 1% valve-uperating gear, owing to the up and down movement midway thrust of the cam not being evenly between the sprockets after distributed, and the akid cam will initial running in, whilst the rear wear badly. Any inaccuracy here chain should have about 1 in. move can be rectified by the judicious use ment. It is ribsolutely essential to make provision for chain-ollers to of a carborundum stick.
the
To find the best jet setting starti off on a rich mixture and after running for a time take out the aparking plug and note ita condi- tion. If the mixture be over-rich, a burnt fuel deposit will be seen on the electrodes and the base of the plug. Carry our experiments using
a jet two sizce smaller each time, until the plug shows clean.
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CHRYSLER
SIX
DIFFERENT
PERFORMANCE
Step into a New Chrysler Six and drive a few miles. You'll acquire new views about performance. You'll understand why we say "Drive a Chrysler and enjoy the difference." The Chrysler Six is delightfully different from other sizes. It is more
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of Chrysler internal-expanding
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0-2)
The
BUICK 8
The Eights with Buick's Prestige
the plug out of commission.
If the mixture be much too weak, The saddle should be as wide as
countrymen. When Fulton's first the handle-bar As I said in the opening para-steamship, The Clermont,' puffed the exhaust pipe will soon show a possible, whilst variety of hues from deep blue to grips should point directly down graph, I have dealt with the subject straw; actually the exhaust pipe wards if the machine is to be used on broad lines. Volumes could be down, the Hudson, wiseacres of the should remain undiscoloured, for track racing. This riding posi-written on high speed tuning, but day predicted dire disaster. The Regarding fuel, I would suggest tion will be found the least tiring after all, having tuned a machine to Wright Brothers' contribution to when a give a reasonable turn of speed, the the cause of aeronautica at Kitty R.D. 1 as being suitable, but a little to the fore-arm muscles experimenting may be indulged in strong grip has to be maintained track will provide much valuable Hawk occasioned one London news- data upon which further tuning can paper to refer to them aa 'those in this direction.
for any period.
fantastic Americana. be carried out.
Taking a particular engine, with dimensions of 74mm. by Bimun., giving a capacity of 360 cc., I give the magneto a considerable degree of advance, some 42° to 45 on the ty-wheels with
the magneto fully advanced. If R.D. 1 is not used as a fuel but, say, a afty-fifty mixture which would be liable to cause de tonation in a high compression en- gine, the advance on the magneto should be reduced.
Quite an important feature is that of riding position, from the point of view of reducing wind resistance to the absolute minimum One should endeavour to He prac- tically horizontal ao that no por- tion of the body will cause any
direct resistance.
In short, actual experience of
"Yet all these developments, proved sound in principle, endured speed work is a very able teacher.
This article has been reprinted through the years, each finally cap- from a very interesting little book turing a dominating position in let "Your Motor Cycle on Road and world progress.
Similarly, Fred Track" which also contains other Wheeling with positive gear control interesting articles by such well-solves a problem which automotive known racers, es Graham Walker, Wilmot Evans etc., The Vacuum Oll years, namely, a safe and efficient engineers have struggled with for Company will be glad to send you
means of harnessing the tremendous a copy if you will apply to their force of momentum and adapting it
to the motor car.
Lubrication. Although I have left the subject of lubrication to the last, actually it is a matter of first importance. No matter how carefully you may tune an engine, all the time and office in King's Building (top floor). work expended can be nullified in We understand that only a limited less than one lap of Brooklands number of coples are available. track if you are not using the 'right oil in the right way.
I have found that Mobiloil gives extremely satisfactory results and I use this lubricant exclusively.
GEAR CONTROL.
The Cycle Parts, There are one or two points in connection with the cycle parts which contribute towards speed and comfort, the latter being an import ant consideration for long-distance work. Good steering is absolutely essential to safety. See that no alde-play exists in the fork links and that the dampar,. if used, is not I adopt a pressure of 10lb. to the Intriguing Query for too tight. Quite frankly, I have square inch In my lubrication” sys-. found little use for a damper. I use tem, the actual oil feed, of course, The 136-lbs.) being carefully regulated. standard forks, with a spring, 8 in. long.
place for the oil is inside the engine The fork spindles should be quite and bad joints, which allow oil to free and well greased,
escape, are inexcusable.
Motorists.
"All question as to the acceptance of Free Wheeling with positive gear control by the engineering world or the public has been definitely re- moved. Even before its introduc tion, highway and safety engineers had accorded it their approval as an Important contribution to greater motoring safety. Its appearance was signalised by instant approval on the part of motorists once they its had investigated and tested. many outstanding advantages. This With good fitting rings and piston Wheeling with positive gear con- favourable public reaction raised Studebaker from tenth to fifth place and a nice cylinder barrel it is troi?
This is a question which la in- in automobile registrations in the almost impossible to over-oll when travelling at speed, but with racing triguing motorists throughout the United States.
"Seven years ago, when balloon plugs, care has to be taken when world since Studebaker's new on- "As to tyre sizes, I use 26in, by running slowly not to use too much interug development was adopted tyrer were first introduced, their merely a 24in. for short-distance work, 27in. as it will get past the piston, by three other well-known makes of
24in. for long-distance work, owing to the high vacuum, and put Lincoln, according to the manager out balloon tyres would stand small
curs, including Pierce-Arrow and universal, adoption was
matter of time. To-day a car with- and 27in. by 241n. front and 27in.]2
of the Hong Kong Hotels Garage, chance of success. In like manner, by. 8in. back, for road work..
Studebaker dealer hero.
See that the wheels are dead in lines and balance thera by means of split lead shot gripped on spokes diametrically opposed to the tyre
valve.
CAM SKID
CAM
INCORRECT Showning effect of
thid.
CORRECT badly-aligned
Will all curs ultimately have Free
..
Free Wheeling, as a fundamental "In searching for an answer a engineering principle which ad- the above query, let us consider vances the modern motor car one sound engineering advancementa, in step nearer its ultimate goal, can- the past. In the 16th century, not be overlooked or ignored for Salomon de Caus, chief engineer to long. Based alone on its self- King Louis XIII of France, dis evident advantage in increased covered steam as a possible motive motoring pleasure, Increased driv force and Was condemned by ing safety, reduced muscular and Cardinal Richellou as a lunatic and mental effort and material saving confined in the asylum of Bicetré. of 15 to 20 per cent, in petrol and "Stephenson's Arat locomotive, oil, it seems inevitable that some "The Rocket, aroused, a storm of day all cars will have Free Wheel- scorn and skepticism among his ing with positive gear control."