Evening star., 1922-10-08

surements apply to cast iron ptstons;
| II aluminium alloy is used more clear
ance must be provided, depending
| upon the co-efficient of expansion OF
The rings which are fitted to every
| gas engine piston are for the purpose
| of sealing the clearance necessary
| between the piston and cylinder wall:
| They are spring rings and will hug"
the cylinder wall closely at all tenn
share of compression making they
must Mt the ring slots in the piston
| closely. There must be absolutely no
| perceptible play Of the piston. trans
! yersely in the slot. The ring must
be thick SO as to reach deeply into
the groove and yet expand sufficiently
| to seal the piston clearance. Piston
| rings wear thin and must be replaced
when worn, while the slots tn themselves
wear. on the shoulders so that the
right angles with the piston sides.
| When this condition of piston and
rings Is reached. good ring fit is Inn
possible and new pistons must be in
stalled
No process but THAI Of fitting each
ring to it's slot by means Of grinding
| them down to fit can give the bost
possible compression.
The valves of an engine play d
large part in compression losses. but
. they are essential to four-cycle en-
| glne operation, so that we must put
up with them and keep them in shape
When the compression on a cylinder
seems to be getting poor it is well to
inspect the valves The seat is likely
70 De pitted or perhaps a layer of
carbon has been deposited. A new
seal must De made, and the process
necessary is called valve grinding
II, however, well seated valves do not
remedy the lack of compression the
oniy other place which can possibly
rings.
Poor compression should not be toll
Grated by any car owner because Of
the following reasons:
l. III does not pay; the fuel and Oil
consumption of such engines is far
greater than it should be.
=. 1t causes overheating, impairs
engine operations and may do damage
oy causing warping Of valves and
scoring Of cylinders.
3: The mileage possible per gallon
OF fuel and oil will be decreased while
the motor will not give signs of hay-
ing any surplus power This is ex-
penslve as well as discouraging to
any driver who takes pride in his cars
performance.
Battery's Place I'm Starting.
Most of us fail to realize what a
battery of three small cells is called
upon to do when turning an engine
over. On a cold morning, when
cylinder oil is stiff. the power re-
CURED to spin the ordinary motor
runs up to from one to two horse
power, and all this is supplied by
the little black box under the seat.
The automobile battery has the power
to deliver tremendous current flow
for short period. But just as surely
as oVercharging causes it to heat up,
SO VIII Notwithstanding cause the
battery to become too hot
knowing this to be true, it is an
have a short life in the hands of
some drivers. Who has not heard
owners of cars repeatedly spin
motor half a minute without let-up
Then without more than few sec
onds' rest. go to it again. One such
treatment is sufficient to buckle and
warp the plates of the best storage
battery. If a motor is hard to start.
the battery should never be asked to
turn it over for longer than three or
four seconds at a time; then give the
battery a short rest. if only a quarter
of a minute, before trying again.
After few trials. get out of the
seat and investigate the carburetor;
make doubly sure that the gas is
there: 1T may not be, but even if it
is. the fact that you are out of the
seat will give the battery a breath
ing spell it would not otherwise re-
ceive.
The starting mechanism of car
guilty party is sure to pay for it
sooner or later. Most of this abuse
Is due to lack of knowledge. Moral
Study your engine,