The Oskaloosa herald. (Oskaloosa, Mahaska County, Iowa) 1885-1919, 1915-12-02

~
times az If too lean. Opening the
throttle wider, the motor picks up and
goes to perfection. There is no trou-
bic except at the seventeen to twenty
one clip. What 10 the matter?
The motor in all probability is get
ting too rich a mixture at speeds be-
tween seventeen and twenty -one miles
per hour, and it Is suggested that you
adjust the low speed as lean as pos
sible, so that by lifting the air valve
even slightly the motor win stop. Also
look at the cam and see that it is not
jammed against the carburetor body at
any point In its travel.
Does il mako any difference In which
direction . generator 10 driven7
This depends upon the type of gen.
orator. Some can be operated in either
direction, while others can be run in
one direction only in order to get eff
cient results.
! What Is the best style Of clutch to
have on a ear-leather face conc type,
multiple disk running in oil or woven
wire asbestos against steel?
The mention of the design of clutch
does not necessarily tell one whether
1t is better than another type, as one
form of cone clutch may be better than
a certain design Of disk and vice versa.
! 1t Is conceded usually the disk clutch
gives easier engaging and Is not SO apt
! to slip owing to its greater fractional
| surface Also grabbing is a condition
which the average disk clutch does not
show. However, some designs of cone
clutches show results which compare
favorably with the best Of disk clutch
es. The disk clutch is more compn-
Gated than the cone, but when 1t comes
to care some disk designs require It
i less frequently than some Of the cones.
Does the lubricating value Of oil ever
diminish after giving miles Of servies7
allowed to stand until clear, can Il DO
used over asain7
The value Of the oil as a lubricant
diminishes as it is used. When in the
motor the oil undergoes decomposition
and after considerable use Is unfit for
further use as lubricant. 1t is a diff
ficult matter to strain oil and remove
all the solid impurities.
= have noticed that the inlet valve Of
q motor remains open some thirty to
fifty degrees past bottom center. |
should think this would allow some Of
the charge taken in to be expelled.
Why is this2
The reason for the intake valve re-
naming open beyond lower dead CEN
ter is to take advantage of the inertia
Of the incoming gases which have been
set in motion by the piston on its sue
ton stroke. AS the piston descends on
the intake stroke with the intake valve
open 1t tends to pull the gases in the
intake valve after 1t. This suction
starts the intake gases in motion, with
the result that they pour rapidly into
the cylinder to I'LL the partial vacuum
in the combustion space. When the
piston reaches the bottom of its stroke
these gases are still in motion, pour
ing into the cylinder, and contain GER
tain amount of energy which causes
them to continue In that direction. In
addition to this there still remains a
partial vacuum in the cylinder which
aids In maintaining the entrance Of the
gases.
1t takes an appreciable time before
the pressure In the cylinder reaches
atmospheric pressure and before the
inertia of the gases has dropped to
such a point that they no longer tend
to rush into the cylinder. For this rea-
son In arranging the valve timing en-
gineers leave the valves open for some
distance past lower dead center. Re
member that for a crank angle Of 80
degrees the piston only travels on the
up stroke about 5 per cent of the total
distance. In other words, for a motor
with four inch stroke the Upward trav-
ell of the piston for a crank angle Of 80
degrees will only. have been OF inch.
For the angle of so degrees the travel
Of the piston on the upward stroke Is
about IA per cent of the total travel.
or, in other words, in a motor of four
inch stroke the travel at the extreme
angle of so degrees would be just a
little over one-half inch. 1t can readi-
ly be seen that this small travel of the
piston would not begin to drive the
gases out of the valve of the inertia
of the incoming charge and the partial
vacuum still remaining.
This Upward travel of the piston, with
the intake valve open, undoubtedly
represents loss Of volumetric eff
cheney In the motor, but there are no
motors in existence which have per
feet volumetrics efficiency, and the 3
per cent loss with a 80 degree angle
Of valve closure would not make any
/. material difference. ~ s...~..
How many speeds are there to the
usual racing car, and, IL more than two,
why are more necessary al
The average racing car has a three
speed gearset. In speedway racing only
!, two speeds are really necessary. but In
road racing three are needed, because
on the turns shifting often Is necessary
from third to second.