More on
auxiliary fuel pumps
Well,
I guess I did it again and got another argument started. It is always
flattering when my articles are copied by other Regions and/or by the national The Self-Starter.
After
all, I write these articles for two reasons. First of all, to share experiences
that may be helpful to other lovers of these fine old LaSalles and its
companion car Cadillac. The second reason is for the thousands of dollars I get
for writing them and the additional royalties I get from the reprintings. The
latter seems to have fallen by the wayside, so I guess I’ll just stick to the
former reason.
Last
January, The Self-Starter reprinted
an article from our Regional newsletter about hot starts on these old cars. In
that article was incorporated some information from an article a few years ago
that had a full explanation of the reasons for parallel installation rather
than series for auxiliary electric fuel pumps. Since Mr. Fay or Mr. Bentwrench
may not have read that article, and for some of you Regional members that might
have missed it, we will review some of those reasons.
Those
of you who are acquainted with me personally know that I have worked on and
loved these old flatheads since the early 1940s. Included is a fair amount of
competitive racing, most of it being in the high altitudes and mountain roads
of
First
of all, let’s review the needs and benefits of installing an auxiliary electric
fuel pump. Primarily it is to recover from, or prevent, vapor lock. Secondly is
that it makes it easier to start one of these old cars after sitting a while
and makes it much easier on the starter motor.
The
third reason is to keep from starving the engine on long uphill pulls, mountain
passes, high altitudes and hot days, no matter where you are. When the car is
starting to starve, it starts to lean out the fuel mixture. The car runs hotter
and adds to the problem of overheating, especially on a long, hard pull.
In
addressing the problem of judges and modifications, I have been judging at
Grand Nationals and Regional Cadillac-LaSalle Club meets for several years as
well as the CCCA. At judges’ meetings it almost always comes up about electric
fuel pumps. The rules are simple: first, it must be auxiliary, not primary (or
only) and the mechanical pump has to be working. Secondly, it must be neatly
installed in a workmanship manner.
Speaking
of installation, now would be a good time to mention a
few installation tips before continuing. You should have a replaceable inline
filter above the rear axle higher than the tank. Then you can change the filter
frequently without spilling a lot of gas. As for the fuel pump itself, the best
place is on the frame about mid-car, lower than the tank, but high enough to be
as much out of sight as possible.
Personally
I prefer the Carter P4259 (6V) rotary—it is much more silent than the pulse
type. When wiring in the pump, there are three pieces of advice. First, get your
power for the pump from the accessory side of the ignition switch so there is
no possible source for power when the key is off. I’ll let your imagination
figure out the safety reasons for this.
Second,
use a push-pull switch rather than a toggle switch and mount it in an
unobtrusive but handy location. That way there is no confusion as to which way
is on or off. Third, be sure of your polarity. You don’t want to be pumping gas
from the carburetor back to the tank.
As
for under the hood, rather than hooking the line directly to the carburetor,
install a tee at the “out” side of the mechanical fuel pump. That way most of
the plumbing is low, mostly out of sight and neat.
Down
to my reasons for parallel rather than series (inline) which are really very
simple. The first obvious reason is that the mechanical fuel pump works easier
when it doesn’t have to pull through the electric pump, just like Mr.
Bentwrench stated. Actually, that is more than you might believe. If you doubt
this, try hooking up a hand vacuum pump on the “out” side of the electric pump,
test it and then do the same thing on the line before the pump. I know that
test impressed me when I tried it.
The
second reason is that pressure from the electric pump into mechanical pump can
cause premature failure of the diaphragm, and if the diaphragm ruptures, you
could still run the car but you could be pumping raw gas into the crankcase. If
you are in parallel, your mechanical can fail completely and you can still
drive the car without serious side effects.
For
many years I used and installed electric fuel pumps inline or series, and agree
with many of you and that it worked fine on my own ’40 LaSalle. I changed over
to the rotary pump several years ago and enjoyed the silence. About four years
ago I reluctantly changed over from series to parallel.
The
following results were experienced. An immediate improvement noticed was the
fact that I didn’t have to use the electric pump nearly as much. Secondly, I
have not had to rebuild or replace the mechanical pump since. The car seems to
run cooler, especially on long mountain passes. By switching on the electric
pump on a hard pull before really needing it, I can drop 15 degrees of
temperature on a hot day, especially at our high altitudes. As the old saying
goes, “Nothing succeeds like success.”
I’ve
learned a lot since the mid- to late ’60s, when I wrote articles for the old
mimeographed The Self-Starter and
they carried me as a tech advisor for 1940 LaSalles. Some methods have stayed
the same and some have improved. After all, someone once said, “The glory of
youth is in strength and agility, while the glory of our elders is in wisdom
and experience.”
See
ya next month,
—Walt