Model engine fuels and lubricants
April 2009 89
The Engine Shop Joe Wagner | [email protected]
Also included in this column:
• Offbeat troubleshooting tips
• Source of replacement
“hardware parts”
Model engine fuels and lubricants come in
many forms. Some of the more
Sneak peek at one of Saito’s new four-stroke controversial of them are shown.
engines specifically made for CL. A full
report on these is coming soon.
This 1950 Forster G-29 (used for
flying Old-Time Stunt) suffered
from erratic “needling.”
Cleaning out its spraybar made
it run like new.
Only one run on the wrong kind of glow fuel ruined a Medallion .15
such as this beyond repair. Coxes require castor oil lubrication.
A SUBJECT THAT comes up regularly in
mail from readers is about fuels for various
types of model engines. I wrote about model
diesel fuel in my previous column; this time
my topic is fuels for glow and “gas”
engines.
For the “gassies,” I’ve been using—and
recommending—Coleman Camp Fuel for
spark-ignition engines. I had two reasons.
The factory instructions for old-time
sparkers specified “white gas” in the fuel
mix. Since it was lead-free, it didn’t build
up deposits inside spark plugs as fast as
automotive gas did. Likewise, its minimal
octane rating aided starting in typical lowcompression
engines such as Brown
Juniors, Ohlsson .23s, and Atom .097s.
White gas was available from service
stations anywhere in America until the
late 1950s. Coleman fuel is the closest
thing to it on the market today.
04sig3.QXD 2/24/09 2:04 PM Page 89
90 MODEL AVIATION
Just one of the many useful-to-modelers listings of hardware and
materials from Small Parts, which also has an online catalog.
The little washer in the foreground is easy to lose. Many O.S.
engines use them; omitting one in reassembly can cause problems.
Most of today’s automotive gasoline
contains alcohol, which damages the
plastic fuel tanks with which so many
prewar spark-ignition engines came
equipped. It also has a detrimental effect
on the plastic gaskets in older-model
Walbro carburetors. I mentioned that in
my recent columns about the Cermark
SPE 26cc and MLD 28cc gas engines.
However, since then I’ve learned that
recent-model Walbro model engine
carburetors use improved gasket
materials. Automotive gas blends don’t
harm them.
One point about Coleman fuel that has
been brought up to me several times is
that it supposedly makes model engines
“run hot.” It does that, all right, and for
two reasons.
First, gasoline contains roughly double
the heat energy of methanol: the major
ingredient in glow fuel. Many modelers
have gotten so used to the heat
characteristics of glow engines that
they’re surprised by the higher
temperature that a gas-fueled engine
normally develops.
Second, gas engines run hot when
modelers lean them out excessively. They
attempt to boost their rpm to something
comparable to what a glow engine
develops. And with any type of internalcombustion
engine, the leaner the
mixture, the hotter it runs.
Another factor that affects model
engine heat output is the oil content: its
type and its amount. Too many modelers
assume that the purpose of oil in their
model engine fuel is merely to make the
moving parts slippery and free-moving.
That’s just one purpose of the oil.
Others are equally important. One is in
producing a load-bearing and rustresisting
film on the working parts, such
as one that can absorb the high pressures
that occur at both ends of connecting rods,
which transfer the entire power output
from their pistons to their shafts.
Another vital function of model engine
oil is its cooling effect. A substantial
amount of excess combustion-chamber
heat is carried out the exhaust in its
ejected oil.
Many modelers consider exhaust oil to
be “wasted.” They believe that since the
engine spits out oil so copiously, there
must be way too much of it in the fuel.
There usually isn’t. The exhaust oil has
already done its work inside the engine,
and now it’s fulfilling its heat-removal
function.
One more important purpose of model
engine oil is as a detonation inhibitor—
akin to water injection in WW II fighter
engines. Detonation produces much
unwanted heat. Adequate oil content
prevents that.
Now for oil type; three basic kinds are
used in model engines. Mineral oil
includes the SAE 70 that was specified for
old-time sparkers. Castor was for decades
the most-used lubricant in glow and diesel
fuel. Synthetic is a manmade oil noted for
its lubricity.
Each type has both good and bad
characteristics. They are as follows.
• Mineral oil is inexpensive and provides
good rust prevention. However, its
viscosity drops as its temperature goes up;
the hotter it gets, the less effective it
becomes as a lubricant. And mineral oil will
burn if it gets too hot, producing carbon
deposits in the combustion chamber.
• Castor oil has the highest film strength
of any model engine lubricant. And since
its viscosity increases as its temperature
rises, it’s especially good in highperformance
engines. Castor is also an
effective antidetonant.
However, its residue is messy and hard
to remove from both the engine exterior
and the airplane. Worse, with time and
exposure to heat, castor oil oxidizes into a
thick, enamel-like coating that can glue a
model engine piston into its cylinder bore
and make a crankshaft impossible to rotate
in its bearing.
• Synthetic oil minimizes friction, won’t
burn or oxidize, and is easy to clean off.
But it provides little rust protection, and
its film strength is far lower than that of
castor. For that reason, many glow fuels
contain a blend of castor and synthetic oil
that works quite well in most of today’s
model engines.
Now for some specifics of use. For
SAM fliers and others who still use oldtime
spark-ignition engines and gas-andoil
fuel, “70-weight” mineral oil is the
lowest viscosity that minimizes wear in
engines such as Ohlssons and Super
Cyclones. It’s hard to find now.
However, many auto-parts dealers
carry Kendall’s Nitro 70 oil. I’ve used
that, and it works well for me—especially
in a 21/2-to-1 mixture of Coleman’s fuel
and Nitro 70.
That brings up a controversial point: the
percentage of oil in model fuel. It would
seem that the lower the oil content, the more
power the engine should develop. After all,
the oil doesn’t burn. By lowering its
percentage, more fuel is available in each
fresh charge in the combustion chamber,
thus producing increased power—right?
Wrong! What determines the power
output of any internal-combustion engine
isn’t the amount of fuel in its combustion
04sig3.QXD 2/24/09 2:19 PM Page 90
chamber, but the amount of oxygen. You
can put any amount of fuel you want into
that chamber by opening the needle valve
wider. That doesn’t increase the power
output, does it? Quite the contrary.
I’ve found that adding castor oil—the
drugstore kind works fine—to the
commercial glow fuel I buy usually adds
power. That’s probably because of a
combination of lowering friction, increasing
compression, and preventing detonation.
Plus, extra castor content is good insurance
against damage from a lean run.
While flying CL one day, I thought I had
brought a full can of my high-oil-content
fuel. But I picked up the wrong can on my
way out of the shop—one that held only a
couple of tankfuls. And two flights weren’t
enough to make me happy.
When another flier offered me some of
his fuel, I unthinkingly accepted. In less
than a minute of my third flight, the Cox .15
in my Chickadee Precision Aerobatics
(Stunt) model quit. Its piston seized in its
cylinder; the rod bent and the case was
damaged. All for the lack of a mere 5% or
so of castor oil in the fuel.
Yes, castor oil has its detriments. I came
across an odd one when helping an Old-
Time Stunt flier solve a mysterious problem
in his Forster G-29. Its needle valve refused
to function consistently. It acted as if the
needle point was bent, but it wasn’t.
The trouble turned out to be a buildup of
congealed castor oil inside the spraybar.
Cleaning that out solved the problem.
On the subject of odd problems, three
times in the last couple of months, readers
have e-mailed me about the same trouble:
formerly sweet-running O.S. engines whose
behavior suddenly changed. They made
“funny noises” when starting, burned out
glow plugs, and simply didn’t “run right”
anymore.
All of these problems stemmed from the
same cause: a missing washer. O.S.
engines—and others—include a thin,
hardened-steel washer that fits between the
crankcase front and the back of the
propeller driver. This is to absorb the
rearward thrust that an electric starter
produces. A missing washer allows the
shaft to move backward—often enough for
the crankpin to scrape the inside of the
backplate.
What I think happened to make the
washer vanish from my readers’ engines
was that, in changing a broken propeller, or
wanting to try a different one, the propeller
driver was also removed. If the washer
adhered to the driver, it could easily have
dropped off into the grass unnoticed.
An excellent source of model engine
fasteners, metal and plastic tubing, O-rings,
and many other items that are useful to us
model engineers is Small Parts, Inc.
For instance, the company carries
almost every size of machine screw—both
metric and U.S. Standard—that we need for
model engines. A size it doesn’t carry is
#3-48, which is used in most small Cox
engines.
The Small Parts catalog has almost 500
pages and is also available online. MA
Sources:
Small Parts, Inc.
(800) 220-4242
www.smallparts.com
Edition: Model Aviation - 2009/04
Page Numbers: 89,90,92
Edition: Model Aviation - 2009/04
Page Numbers: 89,90,92
Model engine fuels and lubricants
April 2009 89
The Engine Shop Joe Wagner | [email protected]
Also included in this column:
• Offbeat troubleshooting tips
• Source of replacement
“hardware parts”
Model engine fuels and lubricants come in
many forms. Some of the more
Sneak peek at one of Saito’s new four-stroke controversial of them are shown.
engines specifically made for CL. A full
report on these is coming soon.
This 1950 Forster G-29 (used for
flying Old-Time Stunt) suffered
from erratic “needling.”
Cleaning out its spraybar made
it run like new.
Only one run on the wrong kind of glow fuel ruined a Medallion .15
such as this beyond repair. Coxes require castor oil lubrication.
A SUBJECT THAT comes up regularly in
mail from readers is about fuels for various
types of model engines. I wrote about model
diesel fuel in my previous column; this time
my topic is fuels for glow and “gas”
engines.
For the “gassies,” I’ve been using—and
recommending—Coleman Camp Fuel for
spark-ignition engines. I had two reasons.
The factory instructions for old-time
sparkers specified “white gas” in the fuel
mix. Since it was lead-free, it didn’t build
up deposits inside spark plugs as fast as
automotive gas did. Likewise, its minimal
octane rating aided starting in typical lowcompression
engines such as Brown
Juniors, Ohlsson .23s, and Atom .097s.
White gas was available from service
stations anywhere in America until the
late 1950s. Coleman fuel is the closest
thing to it on the market today.
04sig3.QXD 2/24/09 2:04 PM Page 89
90 MODEL AVIATION
Just one of the many useful-to-modelers listings of hardware and
materials from Small Parts, which also has an online catalog.
The little washer in the foreground is easy to lose. Many O.S.
engines use them; omitting one in reassembly can cause problems.
Most of today’s automotive gasoline
contains alcohol, which damages the
plastic fuel tanks with which so many
prewar spark-ignition engines came
equipped. It also has a detrimental effect
on the plastic gaskets in older-model
Walbro carburetors. I mentioned that in
my recent columns about the Cermark
SPE 26cc and MLD 28cc gas engines.
However, since then I’ve learned that
recent-model Walbro model engine
carburetors use improved gasket
materials. Automotive gas blends don’t
harm them.
One point about Coleman fuel that has
been brought up to me several times is
that it supposedly makes model engines
“run hot.” It does that, all right, and for
two reasons.
First, gasoline contains roughly double
the heat energy of methanol: the major
ingredient in glow fuel. Many modelers
have gotten so used to the heat
characteristics of glow engines that
they’re surprised by the higher
temperature that a gas-fueled engine
normally develops.
Second, gas engines run hot when
modelers lean them out excessively. They
attempt to boost their rpm to something
comparable to what a glow engine
develops. And with any type of internalcombustion
engine, the leaner the
mixture, the hotter it runs.
Another factor that affects model
engine heat output is the oil content: its
type and its amount. Too many modelers
assume that the purpose of oil in their
model engine fuel is merely to make the
moving parts slippery and free-moving.
That’s just one purpose of the oil.
Others are equally important. One is in
producing a load-bearing and rustresisting
film on the working parts, such
as one that can absorb the high pressures
that occur at both ends of connecting rods,
which transfer the entire power output
from their pistons to their shafts.
Another vital function of model engine
oil is its cooling effect. A substantial
amount of excess combustion-chamber
heat is carried out the exhaust in its
ejected oil.
Many modelers consider exhaust oil to
be “wasted.” They believe that since the
engine spits out oil so copiously, there
must be way too much of it in the fuel.
There usually isn’t. The exhaust oil has
already done its work inside the engine,
and now it’s fulfilling its heat-removal
function.
One more important purpose of model
engine oil is as a detonation inhibitor—
akin to water injection in WW II fighter
engines. Detonation produces much
unwanted heat. Adequate oil content
prevents that.
Now for oil type; three basic kinds are
used in model engines. Mineral oil
includes the SAE 70 that was specified for
old-time sparkers. Castor was for decades
the most-used lubricant in glow and diesel
fuel. Synthetic is a manmade oil noted for
its lubricity.
Each type has both good and bad
characteristics. They are as follows.
• Mineral oil is inexpensive and provides
good rust prevention. However, its
viscosity drops as its temperature goes up;
the hotter it gets, the less effective it
becomes as a lubricant. And mineral oil will
burn if it gets too hot, producing carbon
deposits in the combustion chamber.
• Castor oil has the highest film strength
of any model engine lubricant. And since
its viscosity increases as its temperature
rises, it’s especially good in highperformance
engines. Castor is also an
effective antidetonant.
However, its residue is messy and hard
to remove from both the engine exterior
and the airplane. Worse, with time and
exposure to heat, castor oil oxidizes into a
thick, enamel-like coating that can glue a
model engine piston into its cylinder bore
and make a crankshaft impossible to rotate
in its bearing.
• Synthetic oil minimizes friction, won’t
burn or oxidize, and is easy to clean off.
But it provides little rust protection, and
its film strength is far lower than that of
castor. For that reason, many glow fuels
contain a blend of castor and synthetic oil
that works quite well in most of today’s
model engines.
Now for some specifics of use. For
SAM fliers and others who still use oldtime
spark-ignition engines and gas-andoil
fuel, “70-weight” mineral oil is the
lowest viscosity that minimizes wear in
engines such as Ohlssons and Super
Cyclones. It’s hard to find now.
However, many auto-parts dealers
carry Kendall’s Nitro 70 oil. I’ve used
that, and it works well for me—especially
in a 21/2-to-1 mixture of Coleman’s fuel
and Nitro 70.
That brings up a controversial point: the
percentage of oil in model fuel. It would
seem that the lower the oil content, the more
power the engine should develop. After all,
the oil doesn’t burn. By lowering its
percentage, more fuel is available in each
fresh charge in the combustion chamber,
thus producing increased power—right?
Wrong! What determines the power
output of any internal-combustion engine
isn’t the amount of fuel in its combustion
04sig3.QXD 2/24/09 2:19 PM Page 90
chamber, but the amount of oxygen. You
can put any amount of fuel you want into
that chamber by opening the needle valve
wider. That doesn’t increase the power
output, does it? Quite the contrary.
I’ve found that adding castor oil—the
drugstore kind works fine—to the
commercial glow fuel I buy usually adds
power. That’s probably because of a
combination of lowering friction, increasing
compression, and preventing detonation.
Plus, extra castor content is good insurance
against damage from a lean run.
While flying CL one day, I thought I had
brought a full can of my high-oil-content
fuel. But I picked up the wrong can on my
way out of the shop—one that held only a
couple of tankfuls. And two flights weren’t
enough to make me happy.
When another flier offered me some of
his fuel, I unthinkingly accepted. In less
than a minute of my third flight, the Cox .15
in my Chickadee Precision Aerobatics
(Stunt) model quit. Its piston seized in its
cylinder; the rod bent and the case was
damaged. All for the lack of a mere 5% or
so of castor oil in the fuel.
Yes, castor oil has its detriments. I came
across an odd one when helping an Old-
Time Stunt flier solve a mysterious problem
in his Forster G-29. Its needle valve refused
to function consistently. It acted as if the
needle point was bent, but it wasn’t.
The trouble turned out to be a buildup of
congealed castor oil inside the spraybar.
Cleaning that out solved the problem.
On the subject of odd problems, three
times in the last couple of months, readers
have e-mailed me about the same trouble:
formerly sweet-running O.S. engines whose
behavior suddenly changed. They made
“funny noises” when starting, burned out
glow plugs, and simply didn’t “run right”
anymore.
All of these problems stemmed from the
same cause: a missing washer. O.S.
engines—and others—include a thin,
hardened-steel washer that fits between the
crankcase front and the back of the
propeller driver. This is to absorb the
rearward thrust that an electric starter
produces. A missing washer allows the
shaft to move backward—often enough for
the crankpin to scrape the inside of the
backplate.
What I think happened to make the
washer vanish from my readers’ engines
was that, in changing a broken propeller, or
wanting to try a different one, the propeller
driver was also removed. If the washer
adhered to the driver, it could easily have
dropped off into the grass unnoticed.
An excellent source of model engine
fasteners, metal and plastic tubing, O-rings,
and many other items that are useful to us
model engineers is Small Parts, Inc.
For instance, the company carries
almost every size of machine screw—both
metric and U.S. Standard—that we need for
model engines. A size it doesn’t carry is
#3-48, which is used in most small Cox
engines.
The Small Parts catalog has almost 500
pages and is also available online. MA
Sources:
Small Parts, Inc.
(800) 220-4242
www.smallparts.com
Edition: Model Aviation - 2009/04
Page Numbers: 89,90,92
Model engine fuels and lubricants
April 2009 89
The Engine Shop Joe Wagner | [email protected]
Also included in this column:
• Offbeat troubleshooting tips
• Source of replacement
“hardware parts”
Model engine fuels and lubricants come in
many forms. Some of the more
Sneak peek at one of Saito’s new four-stroke controversial of them are shown.
engines specifically made for CL. A full
report on these is coming soon.
This 1950 Forster G-29 (used for
flying Old-Time Stunt) suffered
from erratic “needling.”
Cleaning out its spraybar made
it run like new.
Only one run on the wrong kind of glow fuel ruined a Medallion .15
such as this beyond repair. Coxes require castor oil lubrication.
A SUBJECT THAT comes up regularly in
mail from readers is about fuels for various
types of model engines. I wrote about model
diesel fuel in my previous column; this time
my topic is fuels for glow and “gas”
engines.
For the “gassies,” I’ve been using—and
recommending—Coleman Camp Fuel for
spark-ignition engines. I had two reasons.
The factory instructions for old-time
sparkers specified “white gas” in the fuel
mix. Since it was lead-free, it didn’t build
up deposits inside spark plugs as fast as
automotive gas did. Likewise, its minimal
octane rating aided starting in typical lowcompression
engines such as Brown
Juniors, Ohlsson .23s, and Atom .097s.
White gas was available from service
stations anywhere in America until the
late 1950s. Coleman fuel is the closest
thing to it on the market today.
04sig3.QXD 2/24/09 2:04 PM Page 89
90 MODEL AVIATION
Just one of the many useful-to-modelers listings of hardware and
materials from Small Parts, which also has an online catalog.
The little washer in the foreground is easy to lose. Many O.S.
engines use them; omitting one in reassembly can cause problems.
Most of today’s automotive gasoline
contains alcohol, which damages the
plastic fuel tanks with which so many
prewar spark-ignition engines came
equipped. It also has a detrimental effect
on the plastic gaskets in older-model
Walbro carburetors. I mentioned that in
my recent columns about the Cermark
SPE 26cc and MLD 28cc gas engines.
However, since then I’ve learned that
recent-model Walbro model engine
carburetors use improved gasket
materials. Automotive gas blends don’t
harm them.
One point about Coleman fuel that has
been brought up to me several times is
that it supposedly makes model engines
“run hot.” It does that, all right, and for
two reasons.
First, gasoline contains roughly double
the heat energy of methanol: the major
ingredient in glow fuel. Many modelers
have gotten so used to the heat
characteristics of glow engines that
they’re surprised by the higher
temperature that a gas-fueled engine
normally develops.
Second, gas engines run hot when
modelers lean them out excessively. They
attempt to boost their rpm to something
comparable to what a glow engine
develops. And with any type of internalcombustion
engine, the leaner the
mixture, the hotter it runs.
Another factor that affects model
engine heat output is the oil content: its
type and its amount. Too many modelers
assume that the purpose of oil in their
model engine fuel is merely to make the
moving parts slippery and free-moving.
That’s just one purpose of the oil.
Others are equally important. One is in
producing a load-bearing and rustresisting
film on the working parts, such
as one that can absorb the high pressures
that occur at both ends of connecting rods,
which transfer the entire power output
from their pistons to their shafts.
Another vital function of model engine
oil is its cooling effect. A substantial
amount of excess combustion-chamber
heat is carried out the exhaust in its
ejected oil.
Many modelers consider exhaust oil to
be “wasted.” They believe that since the
engine spits out oil so copiously, there
must be way too much of it in the fuel.
There usually isn’t. The exhaust oil has
already done its work inside the engine,
and now it’s fulfilling its heat-removal
function.
One more important purpose of model
engine oil is as a detonation inhibitor—
akin to water injection in WW II fighter
engines. Detonation produces much
unwanted heat. Adequate oil content
prevents that.
Now for oil type; three basic kinds are
used in model engines. Mineral oil
includes the SAE 70 that was specified for
old-time sparkers. Castor was for decades
the most-used lubricant in glow and diesel
fuel. Synthetic is a manmade oil noted for
its lubricity.
Each type has both good and bad
characteristics. They are as follows.
• Mineral oil is inexpensive and provides
good rust prevention. However, its
viscosity drops as its temperature goes up;
the hotter it gets, the less effective it
becomes as a lubricant. And mineral oil will
burn if it gets too hot, producing carbon
deposits in the combustion chamber.
• Castor oil has the highest film strength
of any model engine lubricant. And since
its viscosity increases as its temperature
rises, it’s especially good in highperformance
engines. Castor is also an
effective antidetonant.
However, its residue is messy and hard
to remove from both the engine exterior
and the airplane. Worse, with time and
exposure to heat, castor oil oxidizes into a
thick, enamel-like coating that can glue a
model engine piston into its cylinder bore
and make a crankshaft impossible to rotate
in its bearing.
• Synthetic oil minimizes friction, won’t
burn or oxidize, and is easy to clean off.
But it provides little rust protection, and
its film strength is far lower than that of
castor. For that reason, many glow fuels
contain a blend of castor and synthetic oil
that works quite well in most of today’s
model engines.
Now for some specifics of use. For
SAM fliers and others who still use oldtime
spark-ignition engines and gas-andoil
fuel, “70-weight” mineral oil is the
lowest viscosity that minimizes wear in
engines such as Ohlssons and Super
Cyclones. It’s hard to find now.
However, many auto-parts dealers
carry Kendall’s Nitro 70 oil. I’ve used
that, and it works well for me—especially
in a 21/2-to-1 mixture of Coleman’s fuel
and Nitro 70.
That brings up a controversial point: the
percentage of oil in model fuel. It would
seem that the lower the oil content, the more
power the engine should develop. After all,
the oil doesn’t burn. By lowering its
percentage, more fuel is available in each
fresh charge in the combustion chamber,
thus producing increased power—right?
Wrong! What determines the power
output of any internal-combustion engine
isn’t the amount of fuel in its combustion
04sig3.QXD 2/24/09 2:19 PM Page 90
chamber, but the amount of oxygen. You
can put any amount of fuel you want into
that chamber by opening the needle valve
wider. That doesn’t increase the power
output, does it? Quite the contrary.
I’ve found that adding castor oil—the
drugstore kind works fine—to the
commercial glow fuel I buy usually adds
power. That’s probably because of a
combination of lowering friction, increasing
compression, and preventing detonation.
Plus, extra castor content is good insurance
against damage from a lean run.
While flying CL one day, I thought I had
brought a full can of my high-oil-content
fuel. But I picked up the wrong can on my
way out of the shop—one that held only a
couple of tankfuls. And two flights weren’t
enough to make me happy.
When another flier offered me some of
his fuel, I unthinkingly accepted. In less
than a minute of my third flight, the Cox .15
in my Chickadee Precision Aerobatics
(Stunt) model quit. Its piston seized in its
cylinder; the rod bent and the case was
damaged. All for the lack of a mere 5% or
so of castor oil in the fuel.
Yes, castor oil has its detriments. I came
across an odd one when helping an Old-
Time Stunt flier solve a mysterious problem
in his Forster G-29. Its needle valve refused
to function consistently. It acted as if the
needle point was bent, but it wasn’t.
The trouble turned out to be a buildup of
congealed castor oil inside the spraybar.
Cleaning that out solved the problem.
On the subject of odd problems, three
times in the last couple of months, readers
have e-mailed me about the same trouble:
formerly sweet-running O.S. engines whose
behavior suddenly changed. They made
“funny noises” when starting, burned out
glow plugs, and simply didn’t “run right”
anymore.
All of these problems stemmed from the
same cause: a missing washer. O.S.
engines—and others—include a thin,
hardened-steel washer that fits between the
crankcase front and the back of the
propeller driver. This is to absorb the
rearward thrust that an electric starter
produces. A missing washer allows the
shaft to move backward—often enough for
the crankpin to scrape the inside of the
backplate.
What I think happened to make the
washer vanish from my readers’ engines
was that, in changing a broken propeller, or
wanting to try a different one, the propeller
driver was also removed. If the washer
adhered to the driver, it could easily have
dropped off into the grass unnoticed.
An excellent source of model engine
fasteners, metal and plastic tubing, O-rings,
and many other items that are useful to us
model engineers is Small Parts, Inc.
For instance, the company carries
almost every size of machine screw—both
metric and U.S. Standard—that we need for
model engines. A size it doesn’t carry is
#3-48, which is used in most small Cox
engines.
The Small Parts catalog has almost 500
pages and is also available online. MA
Sources:
Small Parts, Inc.
(800) 220-4242
www.smallparts.com