1930-11-13 — Page 11

THURSDAY, NOVEMBER 13, 1930.

MAINTENANCE.

TESTING THE VALVE SEATS.

A good teat to ascertain if a valve seat, is perfect is to mark across the seat of the valve head in several places with a lead pencil or a sharpened piece of chalk, re- place the valve in position, and turn it about one-eighth of a turn, at the same time pressing on the valve If all the marks disappear it indicates that the seat is touch- ing everywhere on the surface. If some of the marks siili show it-in-, dicates that there is a low spot. and the grinding should be con- tinued until the test proves the valve sent to be good. When the grinding is complete the valve should be removed from the cylin- der head, thoroughly washed with kerosene, and the valve guide wiped out carefully. Extreme care should be taken that none of the grinding compound gets into the valve guides or remains the valve or cylinder head. If the valve seat in the head is badly work or seamed it is best to have it reseated with a valve rescating toni. This operation does not re- quire much skill, and the necea- sary reamers can be borrowed from the nearest agent for the tractor.

00

If valves are roplaced, by new ones, the new valves should also be ground in as described. If either the valve guides or steme are worn so that the valve will not seat properly, or an undue amount of air is drawn in along the valve stem, the worn parts should be re- placed by new ones.

Replacing Cylinder Heads. First of all, see that all the sur- inces-cylinder block, cylinder head, and both sides of the gasket -are perfectly clean. Then oll them with cylinder oil. Replace the gasket and head, and turn the nuts up hand tight. The gasket should be placed with the side marked, "This side out" next to the éylinder head.

Put on the case which holds the valve levers. When doing this care should be exercised to be sure that the valve push rods have pro- perly entered the tapered openings in the valve rocker arms. Then

tighten the centre nut on the cylin- der head. Next, tighten the nut directly below it, then the two top nuts holding the valve lever case. The remainder of the outside nuts should be put on hand tight, and gradually tightened all round. After the engine has run for about 10 minutes, retighten all the nuts. Then retighten still another time after the engine has been running for 30 minutes or more. A new gasket always settles a little, and retightening several times is the only way to be aure there will be no leakage. Much trouble from can be avoided if lenky 'gaskets care is taken to tighten and re- tighten the cylinder head nuts each time the cylinder head has been removed.

Valve Timing.

ench

THE CHINA MAIL.

atem. A good way to determine this is to insert a piece of paper between the lower end of the rocket arm and the valve stem, and while silding this paper-back and forth, adjust the adjusting screw until the paper just commences to bind; then move the flywheel to the next marking, 1-10, and adjust the inlet valve in the same, man- дег.

This adjustment should be made with the engine cold, to take care of the expansion in the cylinders. If the engine is worm more clearance should be allowed.

Next revolve the flywheel one half-revolution, and repeat the ad- justment as given above, for the second cylinder, with the 2-XC, and the 2-10 markings.

Piston and Rings.

oil wiper ring at the open end, The piston has åve rings, one an

three used only to retain compres- sion, and the fifth a grooved ring for both compression and lubrica- tion.

others, but has a diagonal groove

The last ring is similar to the To get the best power from the engine, the two valves in

cut in one outside corner which ex-. cylinder must open and close a tends in about an eighth of an follows: The inlet valve should inch. This groove is used as an open 13 degrees after the oil reservoir,. On the back stroke crank has passed head-end dead it collects oil from the walls of the centre (the dead centre near-

cylinder, and distributes it evenly | eat the cylinder), and close 37

on the return stroke on the cylin- degrees after crank-end dead

der walls. This ring is placed in centre. The exhaust valves should

the groove nearest the cylinder open 41 degrees before the crank-head, with the groove extending end and close 11 degrees after towards the cylinder head also. head-end dead centre. The fly. wheel is marked to indicate both the dead centres, also the exhaust and inlet valve opening and clos- Ing as follows:-1-DC is for No. 1 dead centre, 2-DC for No. 2 dead centre, 1XC for No. 1 exhaust closes, XC for No. 2 exhaust closes, 1-10 for No. 1 inlet opens, and 2-10 for No. Z inlet opens.

The crankshaft is in the proper position when the mark referred to ́| is in line with a pointer bolted to the top of the crankcase. To check the timing, turn the flywheel until the exhaust valve of No. 1 cylinder (left hand) has closed and the pointer coincides with the flywheel mark 1-XC; loosen the lock nut on the adjusting screw on top of the rocker arm, and make the neces sary adjustments with a screw- driver, so that there is very little lost motion between the lower end of the rocker arm and the valve

and

Poor Compression. Poor compression is often caused by poor lubrication.

This may arise from using an insufficient. amount of oil, or from an inferior grade of oil. In any internal com- bustion engine the rings platons cannot be made to fit tight enough inside the cylinder walls to prevent gases escaping along the walls. But they must be small enough to slide freely, and in order to get compression, the space between the piston rings and the cylinder walls must be sealed with lubricating oil. It is especially important that a proper oil seal; should be maintained in a kerosene engine: Otherwise, not only is compression lost, but liquid kero- sene works into the crankcase and destroys the lubricating qualities: of the ofl used for the splash system. This is able to injure

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Telephone 30228.

33, WONG NEI CHUNG ROAD, HAPPY VALLEY.

The

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The Eights with Buicks Prestige

ΤΟ YOU AND YOU

OWNERS

OF

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DE SOTO & PLYMOUTH

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IN CASE YOU DO NOT KNOW WE BEG TO

INFORM YOU THAT WE MAINTAIN

A SERVICE DEPARTMENT

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HYDRAULIC BRAKE

SERVICE

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CONSULT US IF YOU HAVE BRAKE TROUBLES

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SOUTH CHINA MOTOR CAR CO.

DES VOEUX ROAD CENTRAL

TELEPHONE

other parts of the motor besides large for the bore. If too large nut screwed against a heavy bar rocking it back, and forth over the pistons and cylinders.

the Joint should be filed until there of iron against the cylinder block centre you can determine if the If the rings have become worn is a clearance of one-six-fourth of and bridged to clear the end of the bearing is too tight by the from use so that they do not fit an inch, when the ring is inserted sleeve, will do the trick.. When sistance it offers. When trying a perfectly, the gases escape past in the cylinder. The ringa should replacing the new sleeve great care bearing the nuts should always be the piston, and result in a loss of fit the grooves snugly, and if too should be taken to get the sleeve. turned up tight. This cannot be power. Kerosene and water will tight they should be smoothed in its proper place; be sure that too strongly emphasised. Do not also leak into the crankcase with down with a plece of fine emery the packing gasket at the crank- turn the nuts backwards in order the oil. Leaky rings can be detect paper. Tack the emery ΟΧΙ 4 case end of the sleeve is in good to get the bearings to run loose ed by a hissing sound coming from smooth fat board and rub the en- condition (if damaged, replace enough. If too tight with both the cylinder when the engine is tire alde of the ring on it at one with new). The chisel marks on nuts drawn up, put in another thin turned over. The best way to de- time.

the head end of the cylinder sleeve shim and tighten again. Tighten tect it is to remove the inspection

should come in perfect alignment each bolt a little at a time until plate from the crankcase, when the- Before replacing the piston be. with the one on the cylinder cast both are tight." leaky piston can be located by get- sure that it is clean and perfectly ing in order that the lubricating ting someone to turn the motor.free from any dirt or gritty sub-ofl holes in the outside and inside The hissing sound may also be que stance. Also see that the cylinders walls coincide. Then put on the to dry pistons. The piston and (combustion chamber end) are cylinder head (without the gasket) cylinder must be well lubricated to cleaned free of all carbon, as any and draw up the cylinder, hoad secure good compression. If a trace of carbon left in the com-

nuts: This will draw the sleeve tractor loses its compression first bustion chamber will obstruct the into place. The head should then Investigate for proper lubrication. free passage of exhaust gases and be removed and the gasket put in- New rings will not give good, com- will tend to collect "carbon". more to place. pression until the engine has been ready? Oll the cylinders thorough- run for a few days,

ly. This can be done by rotating

Replacing the Piston.

Care of the Bearing, To Inspect the connecting rod the hand crank of the lubricator bearings, remove the inspection and spreading the oil over the sur plate from the front end of the face of the cylinder by hand crankcase, and turn the fywheel semble the connecting rod in the until one of the cranks is in the. piston so that the oil hole in the lower position. Place the thumb small end of the connecting rod is and first Anger on the edge of the opposite the oil tube in the top of bearing cap so that the crankshaft

When the bearing is properly fitted install new cotter pins.. Be- fore the engine is run, thoroughly oil the adjusted bearings and examine them through the inspec- tion plate during the first few hours to make sure they are not overheating. The bearings in the connecting rods are cast in place Ein special fixtures. Successful ser- vice from these bearings cannot be expected unless they are replaced in the original manner.

SPRING STRENGTH,

Rings may leak from wear on the sides of the rings and grooves or from wear on the outside which opens the gap between the ends of the ring. If this gap is excessive it will be necessary to insert new rings. Rings also leak from de posits of carbon which collect in the platon. Off the piston thor and the bearing cap can be felt at exactly as it stands, with a two- the bottom of the ring grooves in oughly to ensure a good oil seal the same time. Rack the flywheel seater, four-seater, or Saloon body' the piston and cause them to stick,' between. the rings

and their to and fro. If the bearing has any as the case may be. The very

Some manufacturers make, one' type of chassis which is fitted,

Poor grades of oil also cause them grooves. When replacing the noticeable play It can be detected widely differing, weights of thesa to become gummy and stick. When piston Be sure the ofl hole is on by the feel, and should be adjust bodies, and of the human freight. the cause of leaking compression top. Enter the skirt of the pistoned. Never allow a bearing to be-Hikely to be carried, are not taken is sticking in the groove it may and compress the rings one by one, be remedied by removing and at the same time pushing against come loose enough to cause a knock into consideration.

before adjusting it. The corrent The makers of Rolls-Royce cars cleaning the ringe

the piston with the knee.

time to adjust a bearing is when go to the other extreme for not only Removing Kings

Be careful not to catch a finger its looseness can be detected by do they spring the chassis accord- Care must be taken in removing behind the ring when entering It,

Inspecting.

ing to the weight of the body--they rings from the piston. Work rings as the rings are very sharp, and a Adjusting Connecting Rod Bearing also carry out chassis tests with a are brittle, and easily broken, and painful eut may result. After the When the bearings have become weight equivalent to that of the If they are to be used again they rings have been entered, push the loose from wear, but are not actual body which Is to be fitted. must be removed carefully. Secure piston into place and assemble the damaged by lack of lubrication or

When a chassis ía ndaring com-. three or four strips of metal and a connecting rod bearing on the other reasons, and the bearing la pletion, the coach builders who are screwdriver. Insert one piece of crank pin. If both pistons have smooth, it to only necessary to making the body are called upon to metal under the ring opposite the been removed it is well to connect tighten it. After removing the declare Its finished weight. Springs gap. Then, with the screwdriver one piston at a time and adjust nuts and taking off the bearing cap varying from light to heavy, ac- carefully pry out one end until the bearing to fit properly before the condition of the bearing may cording to the weight of the body, another strip can be inserted replacing the other piston. If new under the other end in the same rings have been installed, open the be determined, and if smooth It are then fitted, and the chassis goes may be replaced after removing through its prolonged tests. After manner. The ringe can then be lubricator adjusting screws lead some of the metal shims from each it has passed a veritable army of slipped off without damage. ing to the cylinder to increase the side. These shims conalet of Inspectors, It is delivered to the

Cleaning Grooves

feed about two drops. The engine number of layers of metal 002 of coach-builders, Remove the rings from the should be-run shout two days be an inch thick, sweated together. The Rolls-Royed tests, however, piston and then scrape the carbon for decreasing the oll to Any number of these layers can be do not fuich there,⠀⠀ Although the from the grobves with a screw normal supply while the new rings, peeled off with a knife until the sale has been completed and the driver Clean them thoroughly are wearing in

desired amount has been removed. company might well repudiate with kerosene and a brush's ff the Renewable Cylinder Bleaves, Good judgment ahould be used stability for overloading, Inspectors rings are to be used sga The ture – The motor la eqsipped with re to the number of layere to be re- are sent to make final tests of the to place them in

ed nowable cylinder sleeves, and if moved, and also that the same finished car, in company with the a ditherions of the cylinders becomes amount is removed from each side coach-builder and the customer, or lack of lubrication, or Be sure to place the caps back ha representative.

Ice, the aleave their original position.

ToAfter the bearings have been set old sleeve use & pallar up and the nuts drawn tight take

should both der to de

It is too opening In

be secured from the a hammer ana block of wood and

If the estimated weight of the body is found to have been inaccur ate the chassis is re-ap

with:

the coach-builder - Is

devise one for this purpound on the cep. Be careful not the work! So extensive is the

bolt, threaded at to let the hammer touch any parts pany's organis

and run through a or bolta, but use the block of wood Inspectors

across the cylinder to hammer on. -- The crankshaft ***?

crankcase, and a ghould then be turned over, and bet