The Washington herald., 1921-06-05
WARPED HEADS
One REASON FOR
FAULTY ACTION
.-rszT
Constantly Exposed to
Hot Flames of Ex-
plosions.
PITTING FREQUENT
Examination Will Reveal
Various Defects That Pre-
vent Functioning.
PITTING FREQUENT

failing of in the form of poor
performance. The time-honored
method of testing the compression
by eranking the engine by hand
slowly to determine the relative re-
sistance offered is a fairly satisfac-
tory way of determining compress
sion--lass. but does not Indicate
where the loss exists.
The owner of a car should bear
in mind that valve heads work IN
an extremely hot atmosphere, since
the heads are in the combustion
chamber and consequently are ex-
posed. to the fame of the explosions.
They must therefore be able to
Withstand the traffic heat without
warping. because II they should
warp .the effectiveness of the valve
to make a perfect joint with its
seat would at once be destroyed.
The reason car manufacturers state
that valves are surrounded by ade-
quate water space" is because they
wish to show that the valves being
properly cooled are not likely to be
affected quickly by the heat. In
some Engines where provision has
not been made for the proper cool
ing of Ithe valves the engines give
continual trouble from loss of COM
preston. valves sticking, valves re-
quiring frequent grinding, misfir-
ing due to Irregularities in the
valve action etc.
Must Examine Valve.
The only safe way an owner can
tell whether a yalvehead is warped
-fa ant ~
badly carbonized is to remove the
valve, examine it and measure it
While rthe compression set is all
right 40 check losses due to poor
valve seating, it must be deter
mined that there is no leakage
elsewhere, as, for example, around
the cylinder head joint or valve
plugs. if such be used, or past poor
ly hitting pistons or rings, or due
to-worn cylinders, etc
After a valve is removed by
means of . valve spring compress
soF permitting. il should first be
carefully cleaned by submersion IN
kerosene. then wiped with a clean
cloth. Examine the face of the
valve for smao black spots Place
the valve upright on a level SUR
face and measure four or five dis
tarces from head to plate.' This
win give you a good check on the
trueness of the head A variation
that can be measured with an ordi-
nary rule may be taken as being
enough to cause poor valve seat
ing. hence leaking of mixture past
the vaiye when II is closed. A
valve with a warped head should
besreplaced-
Test for Stem.
Test the stem for straightness.
Place the stem on a level plate.
whle the head of the valve hangs
over the edge of the plate. The eye
cad instantly detect if the stem Is
straight. If it is bent a little ii
may be Strengthened in a wise. A
bent stem may cause the valve to
stick open, or il also may cause II
to return to its seat too slowly. II
the waive stem is straight il should
be- checked for diameter. The best
waF to do this Is first to polish the
stan with a piece of emery cotton
clcth and then try ii in its particu-
La guide. Place il in the guide
(when the tappet is all the way
DOWN, and holding one hand on
the stem and the other on the head
(to force the valve against its seat)
feH for side play. There should be
none perceptible- II the valve stem
can be shaken in its guide 1t will
allow oil to leak down and air to
leak in. Some of you may notice
that there is oil all around the
vaTve springs and the tappets and
enethe side of the engine on which
the valves are located. That oil
-
waive guides. which. by the way.
may themselves be worn. 1t is pos
sihle in some cases where detach-
ab4e guides are used to install a
new guide to fit the worn stem, but
where this construction is not used
a valve with an oversize stem must
besobtained and fitted to the guide.
1t should be just free enough so it
faDs to its seat after being fitted
ABOUT an inch.
should Measure Springs.
1t the same time the valves are
tested for the defects mentioned the
waive springs should be measured
ana examined. A weak spring is
likely to cause a lot of trouble
Place the spring on a level place
and with the eye notice IL ii Is out
of shape or smaller than any OF the
others, Usually you can stretch ard
bep the spring so it will return
to dts normal shape. but where the
spnng temper is lost bending does
NOT prevent the spring from falling
intp almost any position when in
use, II a spring is known to be
weak because of weakened metal
the best thing to do is to get a
new spring. or as temporary
measure put a lot of washers under
ii 70 compress it still more so as to
get little added pressure.
Bear in mind that lot of the
clicking you hear coming from the
engine comes from the valves being
loose. .slapping in their guides. or
from the tappets wearing oval be-
cause of the side thrust on them
when struck by the cam.
Grinding Next Resort.
When the valves are out of the
engine and the heads are badly car
bonized grinding is resorted to to
make the joint between face and
seat accurate In the shops the
GRADING is a matter of a few min
utes. because the valve is refaced
wirn special tool and the valve
|seat has a new surface cut with
es6atfnk tool. Then the valves are
zrolnd as a sort of finish opera
|tion Without these tools COM
pound must be used to grind the
valve to its seat. Valve grinding
|con1pound may be bought at any
supply store. A little of it is spread
|ovef the face of the valve. the valve
|plaeed-lp its proper position and a
|valre grinding tool or screwdriver