"Twelve miles
to the gallon! And on a long
trip, too! Eighteen miles to the
gallon is what I'm supposed to get with this new car, but do I get it?
I do not!"
Martin
Featherston muttered angrily to himself as he checked, for the fourth time,
his mileage figures against the gas he had used on his recent trip.
"Well," he
growled, snapping his notebook shut, "either those advertisements are a lot
of bunk, or else there's something wrong with this car.
I'd better do something about it."
A few minutes
later, he pulled into the Model Garage, climbed out of his new sedan, and
spotted a huge pair of feet sticking out from underneath another car, "Hey,
Gus!" he called. "Have you got
time to look at my car?"
"Just a minute
and I'll be with you." Came in a muffled voice from Gus Wilson, veteran auto
mechanic and half owner of the establishment, as huge and grimy hand
appeared, gripped a spanner, and disappeared
under the car again.
"Don't you think
I ought to get better than twelve miles to the gallon on a car like this
when I'm off on long trips?" Featherston asked, as Gus started wriggling
out. "Of course, if that
eighteen-to-twenty-miles-a gallon claim of the manufacturers is a lot of
honey then I suppose there's nothing to be done about it.
I've had it at the agency several times, but it always comes back no
better than it was when I brought it in."
Gus chuckled as
he wiped his hands on a wad of waste.
"That claim may be a bit optimistic, but twelve miles to the gallon
certainly is low. You ought to
get at least sixteen or seventeen under average conditions.
Let me try it on the road."
Gus climbed
behind the wheel and Featherston got in beside him.
The car ran with perfect smoothness and, so far as Featherston could
see, gave no indication of poor carburetor adjustment.
The motor did not surge or romp as it would have done if the gas
mixture had been much too rich.
When they got
back to the garage, Gus lifted the hood.
"I suppose the agency men have checked the carburetor, but it won't
do any harm to look at it again," he observed.
He carefully tested the idling adjustment, then removed the top of
the float chamber and noted that the level of the gasoline was at just the
right height.
"And I'll bet
they checked the ignition, too," he muttered, half to himself, as he stood
gazing at the distributor. "So,
chances are the trouble isn't there, although the motor doesn't seem to have
as much pep as it should.
Perhaps the automatic spark control may not be right.
They don't always check that.
I'd better have a look - well, I'll be jiggered!"
He turned to
Featherston in surprise.
"Look at this,"
he called. "See that kink in the
vacuum line to the distributor head?
Somehow that pipe got a twist that closed it up so that the vacuum
can't advance the spark as it should.
The result is that the motor is running with the spark retarded more
than it should be. No
wonder you're getting no economy in your gas consumption!"
The twist in the
vacuum line was in such a location that a casual inspection would not have
revealed it, so that it got by the agency service men.
"Seems to me
these new cars have too many new-fangled gadgets," Featherston observed.
"That couldn't have happened on an old car with plain manual spark
control, could it?"
"No, it
couldn't," Gus admitted, as he measured for a new pipe, "but, on the other
hand, unless you're a real expert, you couldn't hand-control the spark as
accurately as this system does when it's working right."
"And it can't
forget," smiled Featherston reminiscently.
"I can remember when I had the motor boiling hot, and nearly burned
out a set of exhaust valves on an old car because I forgot to advance the
spark. But, in those days we at
least knew enough to blame ourselves for doing something wrong."
"You still can
blame yourself for doing one thing, at least that doesn't help any if you're
after gas mileage records," said Gus, "and that's hopping on the throttle a
couple of times just before you let in the clutch for a start."
"What's the
matter with doing that?" Featherston asked in surprise.
"I do it often just to make sure the motor is running when I'm in
heavy traffic. The blamed thing
is so quiet that I can't tell whether it's stalled or not.
Besides, it seems to make the get-away easier, somehow."
"Did you do it
with your old car?" Gus asked.
Featherston
smiled. "I didn't need to."
You could always tell whether the motor was running, by the noise and
the vibration. And, if you did
hit the throttle quick like that, it usually popped back on you."
"That's just the point," Gus insisted, as he took down a coil of
copper pipe and unbent a length of it.
"Modern carburetors are fitted with a tiny pump hooked to the
throttle in such a way that when you push down the throttle suddenly, a lot
of extra gas is forced into the mixture.
So, when you have to open the throttle quickly, the motor gets extra
gas and takes hold with a strong, steady pull, instead of bucking and
popping like the old-style carburetors did when they were set for a fairly
thin mixture. Now, when you push
down on the throttle two or three times in quick succession before making a
start, the mixture gets so thick you can actually see black smoke come out
of the exhaust. A fellow can
waste a lot of gas that way, so you'd better cut it out.
"As a matter of
fact," he added, "if you want good gas mileage with any kind of a car,
you'll let it gain speed slowly without opening the throttle more than
necessary."
"Are there any
other points about driving a modern car that'll help to improve the gasoline
mileage?" Featherston inquired.
"None about the
driving that wouldn't apply to old cars," Gus replied as he reached over to
make the connection at one end of the vacuum pipe line, "but there are
several points about the new cars that you want to keep in mind if you're
after fuel economy.
"One of them is
right here," he said, as he rested his hand on the air cleaner.
"If you let this gadget get so dirty it doesn't let the air through
freely, the effect is a little bit like riding with the choke on a trifle
all the time, so that more gas will be pulled through the carburetor jets
and you'll get a slightly rich mixture."
"Another
new-fangled gadget to worry about, "laughed Featherston.
"It's up to me, I guess, to keep it clean.
At least, it's easy enough to see when it needs attention - or
shouldn't you let it go till you can see the dirt?"
"You can let it go till it begins to look gray and dusty, but
don't wait till it's all caked up," Gus advised.
"And he sure you oil it, too,. It may seem like a lot of trouble to
clear out the air cleaner now and then, but it's a lot cheaper and easier
than to have the car laid up while you have new pistons and rings put in.
Every bit of grit that gets into the cylinders with the air through
the carburetor may help to form carbon, or else mix with the oil and form a
mild grinding compound tht wears away the cylinder walls, the pistons, and
the rings. Lots of times your
business gives you occasion to drive on unpaved dirt roads where the dust
rises in clouds and the air cleaner is the only thing that stands between
you and a whopper of a bill for the repair of a motor worn out all too soon.
"There's another
point about modern cars that can cut down the mileage, and you can spot it
right away. That is the
condition of the tail pipe. In
modern cars, the tail pipe that carries off the exhaust gases is so long
that it reaches beyond the body in some cases.
The object in making it long that way is to shoot the gases out where
they won't have any chance to drift up into the body of the car.
Exhaust gases are bad medicine.
They always contain a lot of carbon monoxide, and that's a deadly
poison.
"The only trouble
with having the tail pipe go back so far," Gus continued, "is that if you
happen to back into some rubbish, or a pile of rocks, or anything like that,
the end of the pipe maybe folded up so that the gases can't get out freely.
Then you have back pressure and high gas consumption, to say nothing
of loss in power. A brand-new
car stopped by here only yesterday with the tail pipe closed up to a small
crescent of an opening that made the gas hiss as it came out.
So, if you happen to back into anything, be sure to take a look at
the exhaust pipe."
"That's one new-fangled idea that obviously is worth while,"
Featherson remarked. "Any
improvement that will help to keep carbon monoxide out of the car may be a
life saver."
"There are at
least two more old-time troubles that you can't spot by just looking
around," Gus went on. "One of
them is a high carburetor-float level.
If the gas level is too high, there'll be too much gasoline drawn
through the jets and the mixture will be a little rich and not so
economical. In the old days,
when a carburetor got that way, you could spot it quick enough because the
gas would leak out and you could see it dripping - and smell it, too.
"Now, with the
modern down-draft carburetor, the leaking gas goes down into the intake
manifold and there isn't any outside indication.
Of course, witht the modern fuel pump, the gas stops feeding to the
carburetor as soon as you stop the motor, so only a little gas can leak
before the level droops to where it ought to be."
"How about a
leaky float valve or a float that leaks and sinks and doesn't shut off the
gas? How can you locate that
kind of trouble?" Featherston
asked.
"There isn't any
such thing as trouble from a leaky float valve any more," Gus smiled,
"That's one form of grief that modern construction has wiped right out.
In the old days, when you got a leaky float valve, the gas level in
the float chamber would rise as soon as you stopped, till it reached the
level of the jets. Then it would
leak out, and keep on leaking out till the vacuum tank was empty, so that
even a small leak meant quite a lot of gas lost.
Now, with a fuel-pump feed, the fact that the gasoline float valve is
leaking doesn't mean anything unless the leak gets so bad that the valve
leaks gasoline faster than the motor takes it out of the float chamber at
idling speed. When the motor
stops, the leak stops too, because the fuel pump stops supplying gas.
"In the case of sunken float, you'll know it quick enough," Gus
concluded, "because the fuel pump will fill the float chamber right to the
top and then begin squirting gas into the manifold so fast that the motor
will choke up and stop."
The two men got
into the car again this time with Featherston at the wheel.
"Seems to have a bit more pep," he observed, "but I can't see a great
deal of difference."
"You'll see an
improvement in the gas mileage, I'll bet," Gus promised.
"I hope so,"
Featherston said, "but some of the old-timers were economical too!"
"Sure," grinned
Gus, "but why try to compare a lion with a mouse?
How many 100-horsepower old-timers could come anywhere near equaling
this bus for gas economy?"
END
