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Doug,
You really know how to ask simple questions! Sorry to be tardy in getting
back to you but here is the first installment of the lineup as I see it:
The A-40 is not part of the A series as it is a different design altogether
and discussion of it will not be had here. See Chet Peek's new book "Flying
with Forty Horses".
All (the other) A series are 171 cu in displacement 4-cylinder with 3-7/8"
bores and 3-5/8" stroke. The number after the dash is the rated horsepower:
either 50, 65, 75, or 80. There is an obscure hybrid variant of the A
series called the A-100 and that will be discussed at the end of the series.
It is a favorite of mine.
First, the A-50 series:
The A-50 series dash numbers range from the -1 consecutively to the -9.
Some A series have up exhaust, meaning the intake port is on the bottom of
the cylinder and the exhaust port is on the top of the cylinder. Up exhaust
engines include the A-50-1, -2, -3, -4, -5, and -6. The A-50-7, -8, and -9
utilize a cylinder with a down exhaust. Some of the cylinders have only one
spark plug hole, on top, with a cast boss where one could concievably add
the lower hole. These are used on the A-50-1, -4, and -7 and, obviously,
these engines only have one centrally mounted magneto driven directly by
splines machined into the rear of the crankshaft. This makes this
crankshaft very unique to the original A-50 series. This crankshaft equips
my very orignal A-50-5 that utilizes dual mags, even though the splines are
not used to drive anything. The A-50-2, -3, -5, -6, -8, -9 series all have
two spark plugs per cylinder and use dual magnetos. The dual magnetos are
driven off of a gear bolted to the back of the crankshaft so these mags turn
the other way from the single mag setup. So some up exhaust cylinders have
one plug and other up exhaust cylinders use two. Same for the down exhaust
cylinders. Single ignition models were not allowed to be certified after
11/7/41.
The intake elbows used on up exhaust engines have a round cross section
going to a round cross section. The intake elbows used on down exhaust
engines have a square cross section going to a round cross section.
Magnetos are generally the SF-4L or AM-4 (with left hand rotation) for the
single mag and SF-4R or AM-4 (with right hand rotation) for the dual mag
models. However, the A-50-2 is certified only with Dual Bendix Scintilla
WL-4 mags or an Autolite IGW battery ignition (like the point system on
your 1959 El Camino). In addition to the SF-4R and AM-4, the A-50-8 and -9
can also use dual Case 4-CAMA mags. Magneto timing varies from model to
model anywhere from 24 to 28 degress BTDC with some timing different between
left and right mags. Impulse equipped magnetos and what they fit will be
discussed later.
The A-50 series engines utilize a 5.4:1 "low" compression ratio and utilize
a different piston from the other horsepower engines because of this.
Holding them in my hands, it appears to be the same casting as certain A-65
pistons except that the flat top is machined a little lower. The low
compression A-50 series makes its rated power at a low 1900 RPM but yet
usually uses a really large prop. The prop for my Aeronca 50-C is a 76-51.
Big diameter and high pitch. What? On a 50 hp engine? Compare this to a
72-42 used on an A-65. Big diameter equals really big disc. Think how a 50
hp helicopter can lift up vertically with a big prop turning really
slowly... Don't laugh at a 50 hp continental...One famous modestly modified
Aeronca 50-C flown by Johnny Jones flew from Burbank to NYC over
Thanksgiving weekend in 1938 NONSTOP and landed with enough fuel to go 700
more miles!! I would like to recreate this flight one day!!
Some of the A-50 engines utilize a "dry" sump crankcase/accessory case combo
utilizing a remote oil tank. These are the A-50-1, -2, -3. The accessory
cases I have for these are both of magnesium and I do not know if any where
ever available in aluminum. The A-50-4, -5, -6, -7, -8, and -9
crankcase/accessory case combo all utilize a 4-1/2 qt. kidney "wet" sump.
Obviously, a "dry" sump crankcase cannot be used with a "wet" sump accessory
case and vise versa.
A-50 series cases made prior to serial number 115395 (around late 1939) use
a "hard mount" meaning that, if I remember right, four 5/16" bolts hold the
engine to the motor mount without any rubber vibration damping. It was
expected that the airframe designers would make motor mounts that would
incorporate rubber suspension. This was rarely the case, however, and
subsequent serial numbers incorporated the conical rubber mount bosses that
we see most prevalent today.
A-50 series engines generally are equipped with Bendix-Stromberg NA-S3,
NA-S3A1 (the A1 meaning mixture control equipped), or Marvel-Schebler
MA-3-PA carburetors. 1-1/4" venturis on the former and 1-7/32" on the
latter. However, the A-50-4J, -5J, -6J, -7J, -8J, -9J models use a High
Fuel Injector Model A in place of the carb, hence the J suffix. All other
aspects of these engines remain the same.
The unique crankcase, accessory case, and gear train on the
A-50-6, -6J, -9, -9J allow the use of either an Eclipse Type 625 or E-80
electric starter or a Mechanical Hummer X starter. The accesory case has
the magnetos mounted horizontally, one left and one right with the "tops" of
the mags pointing at 3 and 9 o'clock. Non-starter dual mag equipped
accessory cases mount the mags almost vertical, one left and one right with
the "tops" of the mags pointing at 11:30 and 12:30 o'clock. Conversion is
difficult, if not impossible, because the 20 or so parts you need are
scarce. If you want these features, you really have find an engine already
with them.
Some of the crankcases are cast and machined to accept an AC diapghram fuel
pump just like the one on your 1959 Chevy El Camino. It runs off an
eccentric bolted to the front of the camshaft. I am unsure if a fuel
injected engine can be equipped with a fuel pump, though, because the fuel
injector pump runs off of a gear that mounts to the smae part of the
camshaft. The fuel pump equipped models were intended for use in low wing
aircraft that had wing tanks, like the Ercoupe.
All A-50 series crankshafts had an SAE No. 0 tapered output shaft and
utilized a separate hub and key for attachment of the propeller. I have an
original early A-50-5 and it is very apparent that the innards are of
lighter wieght than later versions of the A series. The crankshaft has well
drilled crankpins. The gears have lightening holes drilled in them. The
connecting rods are a slimmer design. Nothing wrong with all this. Just an
observation. I would not be using these lighter components to build up a 65
or higher HP engine, though. So you have to know what you have.
"Dry" wieghts range form 160 to 176 lbs.
There are other comments to be made about the A-50 series but they will wait
until discussion of each of the A series engines is complete.
The A-65 is for next week.
chris
-----Original Message-----
From: TWINBOOM [mailto:[email protected]]
Sent: Tuesday, September 03, 2002 10:43 PM
To: Christian Bobka
Subject: Re: Pietenpol-List: A series, or C series Continental ??
Chris,
When I see manuals for these engines on E-Bay or wherever, they are
always lsted as a "C", or an "A" series. I was just wondering what the
difference was between the two. Here is a copy of what I've seen on the Net,
A-50,A-65,A75,A-80
C-75, C85, C90, 0-200
Just curious if one is better then the other.
Doug B.
Do Not Archive
Doug/Elizabeth Blackburn
ArrowBear Lake Ca.
Inland Slope Rebels, Riverside Ca. http://inlandsloperebels.com
----- Original Message -----
From: "Christian Bobka" <[email protected]>
To: "Twinboom" <[email protected]>
Sent: Tuesday, September 03, 2002 7:28 AM
Subject: RE: Pietenpol-List: A series, or C series Continental ??
> Doug,
>
> Two series? Do you mean the -8 vs the -12?
>
> Chris
>
> -----Original Message-----
> From: [email protected]
> [mailto
[email protected]]On Behalf Of TWINBOOM
> Sent: Tuesday, September 03, 2002 8:33 AM
> To: Pietenpol List
> Subject: Pietenpol-List: A series, or C series Continental ??
>
>
> --> Pietenpol-List message posted by: "TWINBOOM" <[email protected]>
>
> Hey gents,
> No big mdeal here, just wondering what the difference between the
> two series would be, and is one better then the other. Thanks,
>
> Doug Blackburn
>
> Do Not Archive
>
>
> Doug/Elizabeth Blackburn
> ArrowBear Lake Ca.
> Inland Slope Rebels, Riverside Ca. http://inlandsloperebels.com
>
You really know how to ask simple questions! Sorry to be tardy in getting
back to you but here is the first installment of the lineup as I see it:
The A-40 is not part of the A series as it is a different design altogether
and discussion of it will not be had here. See Chet Peek's new book "Flying
with Forty Horses".
All (the other) A series are 171 cu in displacement 4-cylinder with 3-7/8"
bores and 3-5/8" stroke. The number after the dash is the rated horsepower:
either 50, 65, 75, or 80. There is an obscure hybrid variant of the A
series called the A-100 and that will be discussed at the end of the series.
It is a favorite of mine.
First, the A-50 series:
The A-50 series dash numbers range from the -1 consecutively to the -9.
Some A series have up exhaust, meaning the intake port is on the bottom of
the cylinder and the exhaust port is on the top of the cylinder. Up exhaust
engines include the A-50-1, -2, -3, -4, -5, and -6. The A-50-7, -8, and -9
utilize a cylinder with a down exhaust. Some of the cylinders have only one
spark plug hole, on top, with a cast boss where one could concievably add
the lower hole. These are used on the A-50-1, -4, and -7 and, obviously,
these engines only have one centrally mounted magneto driven directly by
splines machined into the rear of the crankshaft. This makes this
crankshaft very unique to the original A-50 series. This crankshaft equips
my very orignal A-50-5 that utilizes dual mags, even though the splines are
not used to drive anything. The A-50-2, -3, -5, -6, -8, -9 series all have
two spark plugs per cylinder and use dual magnetos. The dual magnetos are
driven off of a gear bolted to the back of the crankshaft so these mags turn
the other way from the single mag setup. So some up exhaust cylinders have
one plug and other up exhaust cylinders use two. Same for the down exhaust
cylinders. Single ignition models were not allowed to be certified after
11/7/41.
The intake elbows used on up exhaust engines have a round cross section
going to a round cross section. The intake elbows used on down exhaust
engines have a square cross section going to a round cross section.
Magnetos are generally the SF-4L or AM-4 (with left hand rotation) for the
single mag and SF-4R or AM-4 (with right hand rotation) for the dual mag
models. However, the A-50-2 is certified only with Dual Bendix Scintilla
WL-4 mags or an Autolite IGW battery ignition (like the point system on
your 1959 El Camino). In addition to the SF-4R and AM-4, the A-50-8 and -9
can also use dual Case 4-CAMA mags. Magneto timing varies from model to
model anywhere from 24 to 28 degress BTDC with some timing different between
left and right mags. Impulse equipped magnetos and what they fit will be
discussed later.
The A-50 series engines utilize a 5.4:1 "low" compression ratio and utilize
a different piston from the other horsepower engines because of this.
Holding them in my hands, it appears to be the same casting as certain A-65
pistons except that the flat top is machined a little lower. The low
compression A-50 series makes its rated power at a low 1900 RPM but yet
usually uses a really large prop. The prop for my Aeronca 50-C is a 76-51.
Big diameter and high pitch. What? On a 50 hp engine? Compare this to a
72-42 used on an A-65. Big diameter equals really big disc. Think how a 50
hp helicopter can lift up vertically with a big prop turning really
slowly... Don't laugh at a 50 hp continental...One famous modestly modified
Aeronca 50-C flown by Johnny Jones flew from Burbank to NYC over
Thanksgiving weekend in 1938 NONSTOP and landed with enough fuel to go 700
more miles!! I would like to recreate this flight one day!!
Some of the A-50 engines utilize a "dry" sump crankcase/accessory case combo
utilizing a remote oil tank. These are the A-50-1, -2, -3. The accessory
cases I have for these are both of magnesium and I do not know if any where
ever available in aluminum. The A-50-4, -5, -6, -7, -8, and -9
crankcase/accessory case combo all utilize a 4-1/2 qt. kidney "wet" sump.
Obviously, a "dry" sump crankcase cannot be used with a "wet" sump accessory
case and vise versa.
A-50 series cases made prior to serial number 115395 (around late 1939) use
a "hard mount" meaning that, if I remember right, four 5/16" bolts hold the
engine to the motor mount without any rubber vibration damping. It was
expected that the airframe designers would make motor mounts that would
incorporate rubber suspension. This was rarely the case, however, and
subsequent serial numbers incorporated the conical rubber mount bosses that
we see most prevalent today.
A-50 series engines generally are equipped with Bendix-Stromberg NA-S3,
NA-S3A1 (the A1 meaning mixture control equipped), or Marvel-Schebler
MA-3-PA carburetors. 1-1/4" venturis on the former and 1-7/32" on the
latter. However, the A-50-4J, -5J, -6J, -7J, -8J, -9J models use a High
Fuel Injector Model A in place of the carb, hence the J suffix. All other
aspects of these engines remain the same.
The unique crankcase, accessory case, and gear train on the
A-50-6, -6J, -9, -9J allow the use of either an Eclipse Type 625 or E-80
electric starter or a Mechanical Hummer X starter. The accesory case has
the magnetos mounted horizontally, one left and one right with the "tops" of
the mags pointing at 3 and 9 o'clock. Non-starter dual mag equipped
accessory cases mount the mags almost vertical, one left and one right with
the "tops" of the mags pointing at 11:30 and 12:30 o'clock. Conversion is
difficult, if not impossible, because the 20 or so parts you need are
scarce. If you want these features, you really have find an engine already
with them.
Some of the crankcases are cast and machined to accept an AC diapghram fuel
pump just like the one on your 1959 Chevy El Camino. It runs off an
eccentric bolted to the front of the camshaft. I am unsure if a fuel
injected engine can be equipped with a fuel pump, though, because the fuel
injector pump runs off of a gear that mounts to the smae part of the
camshaft. The fuel pump equipped models were intended for use in low wing
aircraft that had wing tanks, like the Ercoupe.
All A-50 series crankshafts had an SAE No. 0 tapered output shaft and
utilized a separate hub and key for attachment of the propeller. I have an
original early A-50-5 and it is very apparent that the innards are of
lighter wieght than later versions of the A series. The crankshaft has well
drilled crankpins. The gears have lightening holes drilled in them. The
connecting rods are a slimmer design. Nothing wrong with all this. Just an
observation. I would not be using these lighter components to build up a 65
or higher HP engine, though. So you have to know what you have.
"Dry" wieghts range form 160 to 176 lbs.
There are other comments to be made about the A-50 series but they will wait
until discussion of each of the A series engines is complete.
The A-65 is for next week.
chris
-----Original Message-----
From: TWINBOOM [mailto:[email protected]]
Sent: Tuesday, September 03, 2002 10:43 PM
To: Christian Bobka
Subject: Re: Pietenpol-List: A series, or C series Continental ??
Chris,
When I see manuals for these engines on E-Bay or wherever, they are
always lsted as a "C", or an "A" series. I was just wondering what the
difference was between the two. Here is a copy of what I've seen on the Net,
A-50,A-65,A75,A-80
C-75, C85, C90, 0-200
Just curious if one is better then the other.
Doug B.
Do Not Archive
Doug/Elizabeth Blackburn
ArrowBear Lake Ca.
Inland Slope Rebels, Riverside Ca. http://inlandsloperebels.com
----- Original Message -----
From: "Christian Bobka" <[email protected]>
To: "Twinboom" <[email protected]>
Sent: Tuesday, September 03, 2002 7:28 AM
Subject: RE: Pietenpol-List: A series, or C series Continental ??
> Doug,
>
> Two series? Do you mean the -8 vs the -12?
>
> Chris
>
> -----Original Message-----
> From: [email protected]
> [mailto
[email protected]]On Behalf Of TWINBOOM> Sent: Tuesday, September 03, 2002 8:33 AM
> To: Pietenpol List
> Subject: Pietenpol-List: A series, or C series Continental ??
>
>
> --> Pietenpol-List message posted by: "TWINBOOM" <[email protected]>
>
> Hey gents,
> No big mdeal here, just wondering what the difference between the
> two series would be, and is one better then the other. Thanks,
>
> Doug Blackburn
>
> Do Not Archive
>
>
> Doug/Elizabeth Blackburn
> ArrowBear Lake Ca.
> Inland Slope Rebels, Riverside Ca. http://inlandsloperebels.com
>
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