Engine Specifications

Water Cooled: 400 lbs, 4" bore, 5-1/2" stroke, 19" flywheels, 5" pulley, 450 rpm


Air Cooled: 360 lbs, 4" bore, 5-1/2" stroke, 19" flywheels, 5" pulley, 450 rpm


2 HP U.M.A.

This was one of the first engines offered by the "United Manufacturers Association" before the name was changed to the "United Engine Company". These engines are believed to be built by J. Thompson & Sons and strongly resemble a Thompson Tiger engine. These are believed to be produced in 1911.

2-1/2 HP Type B

This was an early engine offered by United. These engines are believed to be built by the Field & Brundage Company, however nothing has surfaced confirming that theory. These are believed to be produced in 1911 or 1912.

500 lbs, 4" bore, 5-1/2" stroke, 22" flywheels

Painted "bright fire engine red" and mounted on "hard maple wood skids painted in attractive colors"

2-1/2 HP Type C

This was an early engine offered by United. These engines are believed to be built by the Nelson Brothers Company. These are normally very low three digit serial numbers. The dating can be roughly determined to 1913-1918.

1-1/2 to 12 HP Type F

These engines were built by Waterloo and are normally found in the 36XXX-80XXX serial number range. There are a few engines that are outside of this range. These engines can be accurately dated using Waterloo serial lists (found under the "Other Valuable Sites" tab) and were produced from 1908-1915.

Hopper Cooled:

1-1/2 HP: 350 lbs, 3-1/2" bore, 5" stroke, 19" or 18.5" flywheels, 50 lb flywheel

2-1/2 HP: 600 lbs, 4.5" bore, 6" stroke, 22" flywheels

4-1/2 HP: 900 lbs, 4.5" bore, 9" stroke, 26" flywheels

6 HP: 1400 lbs, 5.5" bore, 10" stroke, 38" flywheels

8 HP: 1700 lbs, 6" bore, 12" stroke, 38" flywheels

12 HP: 2650 lbs, 7.5" bore, 14" stroke, 46" flywheels


Air Cooled:

1-1/2 HP: 3-1/2" bore, 5" stroke, 19" or 18.5" flywheels, 50 lb flywheel




Type H

These engines were built by Associated and are throttle governed. They usually come with a kerosene fuel mixer and a gooseneck trip. These were produced starting 1915.

6 HP Type S

These engines were built by Associated and are normally 4.5 HP engines that were up-rated to 6 HP in 1922.

Type A Engine Trucks

Associated Engine Trucks were likely used under United engines from time to time. These are specs of Associated trucks.

Wheelbarrow trucks: Suitable for engines up to 2-1/4 HP

No. 1 Truck: Suitable for engines up to 3 HP, 9" front, 12" rear, 2" face, 500 lb capacity

No. 2 Truck: Suitable for engines up to 3 HP, 9" front, 12" rear, 2" face, with steel angle iron frame 48" long, 1-1/2" depth, 500 lb capacity

No. 3 Truck: Lineshaft equipped on the truck for easily changing the application of use. 10" x 3" drive pulley with a 7", 5", and 4" pulley for applications each having a 2" face. 9" front, 12" rear, 2" face, with steel channel iron frame 48" long, 3" depth, 500 lb capacity

No. 4 Truck: Designed for use with the 4 and 6 HP engines. 14" front, 20" rear, 3" face, with steel channel iron frame 66" long, 5" depth, 1500 lb capacity

No. 5 Truck: Designed for use with the 6 and 8 HP engines. 26" front, 34" rear, 4-3/8" face, with steel channel iron frame 96" long, 6" depth, 2500 lb capacity. Sub-base removed for use on truck.

No. 6 Truck: Considerably larger than the No. 5. 26" front, 36" rear, 4-3/8" face, with steel channel iron frame 96" long, 7" depth, 5000 lb capacity. Sub-base removed for use on truck.

1-1/2 HP Type A

These engines were built by Associated and are normally found in the 250XXX-251XXX serial number range. There is one engine that is known to be out of that range. These are one of the hardest size United to find. The engines on registry all have a gooseneck igniter trip, top fill fuel tank in the base, and are either battery ignition or a 4 bolt magneto. None have been found with a 2 bolt magneto indicating that these were produced between 1916 (gooseneck starts) and 1924 (2 bolt magneto starts).


1-1/2 HP Type A Air Cooled


380 lbs, 3.75" bore, 5" stroke, 18" flywheels, 1.375" crankshaft, 40 lb flywheel, 6" x 4" flat pulley, 450 rpm

1-3/4 HP Type A Air Cooled

These engines were built by Associated and are normally found in the 80XXX-83XXX serial number range. There are a few engines that are known to be out of that range. These engines are seen with both types of igniter trip, battery/2/4 bolt magneto ignition, EZV/cup/J style mixers, and mostly all side fill fuel tanks in the base. These are the most common size air cooled Type A engine that United sold. These engines are believed to be produced from 1913-1929.

These could have come with just the base, on wood skids, or on a number 2 hand truck with 10" front wheels and 12" rear wheels.

400 lbs, 3.75" bore, 5" stroke, 18" flywheels, 1.375" crankshaft, 40 lb flywheel, 6" x 4" flat pulley, 450 rpm

1-3/4 HP Type A

These engines were built by Associated and are normally found in the 100XXX-115XXX serial number range. There are a few engines that are known to be out of that range. These engines are seen with both types of igniter trip, battery/2/4 bolt magneto ignition, EZV/cup/J style mixers, and either a fuel tank in the base with a side fill or an exterior fuel tank in front of the engine, usually mounted on a battery box. These can be found with an original decal on the hopper or "United 1-3/4 HP" stencilled on the hopper. These are one of the most common size United available. These engines are believed to be produced from 1913-1929.

These could have come with just the base, on wood skids, or on a number 2 hand truck with 10" front wheels and 12" rear wheels.

3.75" bore, 5" stroke

2 HP Type A

These engines were built by Associated and are normally found in the 116XXX-122XXX serial number range. There are a few engines that are known to be out of that range. These engines are seen with the gooseneck trip, battery or 2 bolt magneto ignition, mostly J style mixers, and mostly a fuel tank in the base with a side fill with a flip top lid. A United decal on the hopper is believed to be the only style on this size (no stenciling). These engines are essentially the same as the 1-3/4 hp but were produced after 1922 when Associated up-rated their engines. These engines are believed to be produced from 1922-1929.

These could have come with just the base, on wood skids, or on a number 2 hand truck with 10" front wheels and 12" rear wheels.

500 lbs, 4" bore, 5" stroke, 20" flywheels

2-1/4 HP Type A

These engines were built by Associated and are normally found in the 200XXX-205XXX serial number range. There are a few engines that are known to be out of that range, and there are a few 2-1/2 HP engines in this range as well. These engines are seen with either a straight or gooseneck trip, battery/2/4 bolt magneto ignition, and mostly a side fill fuel tank in the base of the engine. These engines have been found with original decals and stenciling on the hopper. These engines are believed to be produced from 1915-1929.

These could have come with just the base, on wood skids, or on a number 2 hand truck with 10" front wheels and 12" rear wheels.

700 lbs, 4.25" bore, 6" stroke, 22" flywheels, 1.625" crankshaft, 75 lb flywheel, 10" x 6" flat pulley, 400 rpm

2-1/2 HP Type A

These engines were built by Associated and are normally found in the 150XXX-154XXX serial number range. There are a few engines that are known to be out of that range. These engines are usually seen with the straight trip, battery or 4 bolt magneto ignition, mostly cup style mixers, and mostly an exterior fuel tank in front of the engine, mounted on a battery box. A United decal on the hopper is believed to be the only style on this size (no stenciling). These engines are believed to be produced from 1913-1915.

These could have come with just the base, on wood skids, or on a number 2 or 3 hand truck with 10" front wheels and 12" rear wheels.

750 lbs, 4.5" bore, 6" stroke, 24" flywheels

3-1/2 HP Type A

These engines were built by Associated and are normally found in the 155XXX-160XXX serial number range. There are a few engines that are known to be out of that range. These engines are usually seen with the gooseneck trip, battery or 4 bolt magneto ignition, and mostly a side fill fuel tank in the base of the engine. A "United 3-1/2 H.P." stencil on the hopper is believed to be the only style on this size (no decal). These engines are believed to be produced from 1915-1929.

These could have come with just the base, on wood skids, or on a number 3 hand truck with 10" front wheels and 12" rear wheels.


1000 lbs, 4.75" bore, 8" stroke, 27" flywheels, 1.75" crankshaft, 175 lb flywheel, 12" x 6" flat pulley, 375 rpm

4-1/2 HP Type A

These engines were built by Associated and are normally found in the 400XXX-402XXX serial number range. There are a few engines that are known to be out of that range. These engines are usually seen with both style trips, battery or 4 bolt magneto ignition, and mostly a side fill fuel tank in the base of the engine. The only remaining original paint engine on the registry (that shows hopper artwork) has a decal on the hopper. These engines are believed to be produced from 1913-1929.

These could have come with just the base, on wood skids, or on a number 3 hand truck with 10" front wheels and 12" rear wheels.

1700 lbs, 6" bore, 10" stroke, 40" flywheels, 2.25" crankshaft, 250 lb flywheel, 18"-8" flat pulley, 300 rpm

2100 lbs on trucks

2400 lbs with 30" saw on trucks

6 HP Type A

These engines were built by Associated and are normally found in the 600XXX-602XXX serial number range. There are a few engines that are known to be out of that range. These engines are usually seen with both style trips, battery or 4 bolt magneto ignition, and mostly a side fill fuel tank in the base of the engine. These engines have been seen with both a decal and stenciling on the hopper. These engines are believed to be produced from 1913-1929.

These could have come with just the base, on wood skids, or on a number 5 horse truck with 26" front wheels and 34" rear wheels with a 4-3/8" face.

2100 lbs, 6.75" bore, 10" stroke, 42" flywheels, 2.5" crankshaft, 275 lb flywheel, 18" x 8" flat pulley, 275 rpm

2600 lbs on trucks

2900 lbs with 30" saw on trucks

9 HP Type A

These engines were built by Associated and are normally found in the 700XXX serial number range. These engines have been found with the straight igniter trip, battery or 4 bolt magneto ignition, and mostly an exterior fuel tank behind the engine. These engines are believed to be produced from 1913-1929.

These could have come with just the base, on wood skids, or on a number 5 horse truck with 26" front wheels and 34" rear wheels with a 4-3/8" face.

3000 lbs, 8" bore, 13" stroke, 48" flywheels, 2.75" crankshaft, 500 lb flywheel, 24" x 8" flat pulley, 250 rpm

3500 lbs on trucks


12 HP Type A

These engines were built by Associated and are normally found in the 900XXX serial number range. So few of these remain it is hard to specify what features were available. These engines are believed to be produced from 1913-1929.

These could have come with just the base, on wood skids, or on a number 6 horse truck with 26" front wheels and 36" rear wheels with a 5" face.