International C221 Specifications
| Engine Model: International Harvester C221 |
| Engine Type: 4-stroke in-line 6-cylinder liquid-cooled gasoline |
| Total Displacement: 221 cu.in (3.6 L) |
| Rated Engine Power: 65-75 Hp (48-56 kW) at 2400 rpm |
| Fuel System Type: Updraft carburetor |
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The International C221 is a classic inline
6-cylinder gasoline engine produced by International Harvester (IH)
during the 1950s and 1960s. It was a staple in their agricultural
lineup, powering popular tractors like the Farmall 460 and the
International 560. The engine belongs to a modular IH family that shared
many design elements with its diesel counterpart, the D236, as well as
larger displacement variants including the C263, C291, and C301.
The C221 evolved from the Silver Diamond and Black Diamond truck engine
families first introduced by International Harvester in 1949, replacing
the older flathead Green Diamond design. This lineage gave the C221 a
robust foundation suited for heavy-duty continuous operation. The engine
features an overhead valve (OHV) configuration, a seven-main-bearing
crankshaft for exceptional smoothness, and a pressurized cooling system.
Available in both standard gasoline and LP gas versions, the C221 became
a workhorse for small to medium-sized farm tractors, combines, cotton
pickers, forklifts, industrial power units, and some light-duty
crawlers. Its reputation for reliability and the widespread availability
of parts have ensured the C221 remains a popular engine for restoration
and maintenance projects.
Engine Type: 4-stroke, inline-6, gasoline (LP Gas versions also
available).
Displacement: 221 cu.in (3.6 L).
Bore x Stroke: 3.5625 in x 3.6875 in (90.5 mm x 93.7 mm).
Compression Ratio (Standard Gasoline): 7.4:1.
Compression Ratio (LP Gas): Higher than standard gasoline.
Firing Order: 1-5-3-6-2-4.
Gross Horsepower: 65-75 hp at 2,400 rpm.
PTO Horsepower (Farmall 460): 48-52 hp.
Rated Engine Speed: 1,800 rpm to 2,400 rpm.
Peak Torque: 165-175 lb-ft (224-237 Nm).
Valvetrain: Overhead valve (OHV), mechanical tappets (solid lifters).
Fuel System: Single updraft carburetor, Marvel-Schebler or IH-branded.
Ignition System: Battery ignition with distributor, coil, and breaker
points.
Electrical System: 12V with generator (original equipment).
The cylinder block is constructed from cast iron, a material providing
high durability, excellent thermal stability, and resistance to warping
under sustained heavy loads. The block features an inline 6-cylinder
configuration with a deep-skirt design for rigidity. A distinguishing
feature of the C221 block is the seven-main-bearing crankshaft support.
This design uses seven bearings to support the crankshaft, offering
superior stability and reducing internal vibration compared to the
4-cylinder engines common in the same era. This multi-bearing layout
contributes directly to the engine’s smooth operation and long service
life in demanding agricultural environments.
The block incorporates a full water jacket surrounding each cylinder
bore to maintain uniform operating temperatures. Cast into the block are
the mounting bosses for the engine’s side mounts, the distributor, the
oil pump, and the starter motor. The bellhousing pattern is specific to
International Harvester’s tractor and industrial transmissions. On
gasoline versions, the cylinder bores are machined directly into the
cast iron block. Replacement pistons are available in standard oversizes
to accommodate block reboring during rebuilds.
The cylinder head is a separate cast iron unit, bolted to the block
using a head gasket. It houses the overhead valve mechanism, including
the valves, valve springs, rocker arms, pushrods, and rocker shaft.
Intake and exhaust valves are arranged in an inline pattern along the
head. The combustion chamber is of a wedge or bath-tub design, shaped to
promote efficient flame travel and complete combustion of the air-fuel
mixture.
The valve train is actuated by a camshaft located in the cylinder block.
Mechanical tappets (solid lifters) ride on the cam lobes and transfer
motion through pushrods to the rocker arms. The rocker arms then open
the valves against spring pressure. This system requires periodic manual
adjustment of valve clearance (tappet lash) to maintain proper timing
and prevent valve damage. The cylinder head casting uses distinct part
numbers, including 367188R and 373423R, which are shared across the C221
and C263 engine models. Valve sizes for the C221 include an intake valve
head diameter of 1-21/32 in (42 mm).
The fuel system on the standard C221 gasoline engine uses a single
updraft carburetor mounted low on the engine. Air and fuel enter from
below, drawing upward into the intake manifold. This updraft design was
common on early tractors as it reduces the risk of fuel leakage onto the
hot engine. The carburetor receives fuel from a mechanical fuel pump
mounted on the engine block or from a gravity-feed tank depending on the
vehicle application.
LP Gas versions of the C221 exist, utilizing a vaporizer/regulator to
convert liquid propane into vapor before it enters the intake manifold.
The intake manifold itself is a cast iron unit with a single inlet
plenum feeding six individual runners to each cylinder. The manifold is
heated by exhaust gases passing through a crossover passage beneath the
carburetor.
The lubrication system is a fully pressurized, wet-sump design. A
gear-type oil pump, driven from the distributor shaft, draws oil from
the oil pan through a screened pickup tube. The oil is forced through a
full-flow, spin-on or cartridge-type oil filter before being distributed
to the main galleries. From the main galleries, oil is supplied to the
seven crankshaft main bearings, the six connecting rod bearings, the
camshaft bearings, and the valve train components.
The rocker arm assembly receives oil through a hollow rocker shaft,
which feeds each rocker arm. Excess oil drains back through the cylinder
head and block into the oil pan. The oil pan capacity is 8 U.S. qt (7.6
L) including the filter. Oil pressure is regulated by a spring-loaded
relief valve to prevent over-pressurization of the system at high engine
speeds. A dipstick provides a convenient method for checking oil level.
The cooling system is a pressurized water-circulation design. A
centrifugal water pump, driven by a fan belt from the crankshaft pulley,
circulates coolant through the engine block and cylinder head. Coolant
flows from the water pump into the block’s water jacket, surrounding the
cylinders, then moves upward into the cylinder head before exiting
through the thermostat housing and returning to the radiator.
A wax-type or bellows-type thermostat maintains operating temperature by
regulating coolant flow. The total cooling system capacity varies
depending on the specific vehicle radiator but generally falls between
22 and 25 U.S. qt (21-24 L). A fan mounted to the water pump draws air
through the radiator core to dissipate heat. The system is sealed with a
pressure-type radiator cap, raising the boiling point of the coolant to
prevent overheating under heavy load conditions.
Ignition System: The ignition system is a standard battery-and-coil
design. A 12 V battery supplies power to the ignition coil, which steps
up the voltage. The distributor, driven by the camshaft, routes
high-voltage pulses to each spark plug in the correct firing order
(1-5-3-6-2-4). The distributor contains breaker points (contact points)
that open and close to trigger the coil discharge. A centrifugal advance
mechanism inside the distributor adjusts ignition timing based on engine
speed. Many original tractors used a generator for electrical power,
though aftermarket alternator conversions are now common.
Electrical System: The original electrical system operates at 12 V with
a negative ground. Components include a battery, a starter motor, a
generator (or alternator in conversions), a voltage regulator, and the
ignition system wiring. The starter motor is a high-torque unit designed
to crank the engine against the high compression of the 7.4:1 ratio.
Exhaust System: The exhaust manifold is a cast iron unit bolted to the
cylinder head. It collects exhaust gases from all six cylinders and
directs them into a single outlet. The manifold often incorporates the
heat riser passage for intake manifold heating.
Engine Mass (Dry): 800-850 lb (363-385 kg) without coolant or oil but
including manifolds and flywheel.
Overall Length: 35-38 in (889-965 mm), varying slightly with
front-mounted accessories.
Overall Width: 24-26 in (610-660 mm).
Overall Height: 30-33 in (762-838 mm) from the bottom of the oil pan to
the top of the valve cover or air cleaner.
Engine Oil Grade: SAE 30 (summer) or SAE 10W-30 (multi-grade) for
gasoline engines.
Engine Oil Capacity: 8 U.S. qt (7.6 L) including the oil filter.
Coolant Capacity: 22-25 U.S. qt (21-24 L) total system capacity.
Spark Plug Type: Champion or equivalent; specific heat range per
application.
Spark Plug Gap: 0.025 in (0.635 mm).
Breaker Point Gap: 0.020 in (0.508 mm).
Ignition Coil: 12 V, external ballast resistor on some applications.
Valve (Tappet) Clearance (Intake and Exhaust): 0.027 in (0.686 mm).
Firing Order: 1-5-3-6-2-4 (cylinder number 1 at front, radiator end).
Idle Speed (Tractor Applications): 450-500 rpm for smooth operation.
Cylinder Head Bolts: 90-100 lb-ft (122-136 Nm).
Connecting Rod Cap Bolts: 40-45 lb-ft (54-61 Nm).
Main Bearing Cap Bolts: 85-95 lb-ft (115-129 Nm).
Flywheel Bolts: 55-60 lb-ft (75-81 Nm).
Intake and Exhaust Manifold Nuts: 25-30 lb-ft (34-41 Nm).
Rocker Arm Shaft Bracket Bolts: 25-30 lb-ft (34-41 Nm).
Oil Pan Bolts: 7-9 lb-ft (9-12 Nm).
Spark Plugs: 25-30 lb-ft (34-41 Nm).
Water Pump Bolts: 15-20 lb-ft (20-27 Nm).
Starter Motor Mounting Bolts: 35-40 lb-ft (47-54 Nm).
Valve Cover Nuts: 4-6 lb-ft (5-8 Nm).
The International C221 engine was used widely across International
Harvester’s agricultural and industrial lines.
Tractors:
Farmall 460 (row-crop tractor)
International 460 (utility/wheatland version)
International 560 (early production before transition to C263)
International 606 (utility tractor)
International 2606 (industrial tractor)
International 3616 (industrial tractor)
Combines and Harvesters:
International 205 Combine
International 303 Combine
International 315 Combine
The engine identification code "C221" appears on the engine block serial
number pad. Production spanned roughly from the mid-1950s through the
mid-1960s, with the engine eventually superseded by larger-displacement
variants of the same family for higher-power applications. Parts
interchangeability exists across many C221, C263, and C291 components,
including cylinder heads and valvetrain parts.
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| Outboard Engines Technical Specifications |
