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International C221 Engine

The International Harvester C221 is a heavy-duty, 6-cylinder inline, spark-ignition internal combustion engine developed for agricultural and industrial applications. It was prominently featured in mid-century machinery, including the Farmall 460 tractor. Constructed with a robust cast-iron block and cylinder head, this power unit belongs to IH’s family of modular 6-cylinder engines. It is engineered for low-end torque durability, simple mechanical serviceability, and reliable continuous operation under high agricultural loads.

The engine uses an overhead valve (OHV) setup with two valves per cylinder operated by mechanical lifters, pushrods, and a rocker arm assembly. The valve train includes stellite-faced exhaust valves and mechanical rotocaps to ensure uniform heat distribution and reduce wear during continuous high-load operations. Valve clearance adjustments are performed at the rocker shaft mechanism located beneath the top valve cover. Displacement: 221 cubic inches (3.6 liters). Bore: 3.5625 inches (90 mm). Stroke: 3.6875 inches (94 mm). Compression Ratio: 7.2:1.

The fuel system is designed to handle gasoline or liquefied petroleum gas (LPG). For gasoline configurations, fuel is delivered via an engine-driven mechanical fuel pump to an up-draft or side-draft single-venturi carburetor. Intake air passes through a heavy-duty oil-bath air cleaner to remove fine dust before entering the induction manifold. Engine speed is managed by an external mechanical flyweight governor linked directly to the carburetor throttle shaft to balance load and fuel delivery.

The lubrication system is a full-pressure feed system powered by a gear-driven oil pump located inside the lower crankcase oil pan. Oil is drawn through a pickup screen and forced through a replaceable full-flow oil filter element. Pressurized pathways channel oil directly to the main bearings, connecting rod journals, camshaft bearings, and up to the overhead rocker arm assembly. System pressure is monitored and maintained by an integrated spring-loaded oil pressure relief valve.

Engine cooling is handled by a forced liquid-circulation system driven by a front-mounted, belt-driven centrifugal water pump. Coolant flows through cast jackets within the cylinder block and head to absorb combustion heat before returning to an external radiator. Temperature regulation is maintained by a pellet-type thermostat housed in the water outlet neck, ensuring the engine quickly reaches and holds its optimum operating temperature.

General Technical Data

Engine Specifications

Engine Model ............... International Harvester C221
Engine Type ............... 4-cycle inline 6-cylinder overhead valve liquid-cooled gasoline/LPG
Number of Cylinders ............... 6
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 3.5625 (90.50)
Engine Stroke, in (mm) ............... 3.6875 (93.66)
Displacement, cu.in (L) ............... 221 (3.6)
Rated Engine Power, hp (kW) ............... 55-68 (41-51)
Rated Engine Speed, rpm ............... 1800
Peak Torque ............... 175 lb-ft (237 Nm) at 1200 rpm
Low Idle Speed ............... 425-450 rpm
High Idle Speed ............... 1975 rpm
Operating Speed ............... 1800 rpm
Compression Ratio ............... 7.2:1
Firing Order ............... 1-5-3-6-2-4
Cylinder Block Type ............... Cast iron sleeveless block design
Cylinder Head Type ............... Cast iron overhead valve single piece
Manifold Configuration ............... Cross-flow intake and exhaust layout
Camshaft Drive ............... Gear-driven helical train
Lubrication System ............... Full-pressure internal gallery
Oil Pump Type ............... Gear-driven internal
Oil Filter Type ............... Full-flow spin-on cartridge
Cooling System ............... Liquid-cooled pressurized bypass
Water Pump Type ............... Belt-driven centrifugal impeller
Air Cleaner Type ............... Oil bath heavy-duty or dual-element dry type
Ignition System Type ............... Battery-coil distributor ignition
Spark Plug Type ............... Champion D16 or equivalent
Breaker Point Gap, in (mm) ............... 0.020 (0.51)
Spark Plug Gap, in (mm) ............... 0.023 (0.58)
Starting System ............... Electric Starter
Electrical System ............... 12 V negative ground
Alternator Charging Output ............... 35 A

Fuel System

Fuel Delivery Type ............... Carbureted updraft induction system
Carburetor Model ............... International Harvester
Fuel Options ............... Gasoline or Liquefied Petroleum Gas
Fuel Strainer Type ............... Sediment bowl with fine mesh screen
Fuel Pump Type ............... Mechanical diaphragm camshaft driven
Fuel Pressure Range, psi (bar) ............... 3.0-4.5 (0.21-0.31)
Main Jet Type ............... Fixed or adjustable metering needle variable
Idle Jet Type............... Fixed orifice economy calibration
Float Level Setting, in (mm) ............... 0.281 (7.14)
LP Gas Regulator Type ............... Two-stage dry gas vaporizer converter
LP Gas Lockoff Valve ............... 12V electric solenoid safety shutoff
Air-to-Fuel Ratio Range ............... 12.5:1 to 14.7:1
Governor Type ............... Flyball mechanical variable speed
Governor Linkage Style ............... Direct rod link with anti-backlash spring
Choke Valve Type ............... Butterfly disk with spring-loaded relief valve
Throttle Bore Diameter, in (mm) ............... 1.25 (31.75)
Venturi Diameter, in (mm) ............... 1.031 (26.19)

Dimensions and Weight

Overall Length, in (mm) ............... 38.4 (975)
Overall Width, in (mm) ............... 22.8 (580)
Overall Height, in (mm) ............... 34.2 (870)
Dry Weight, lbs (kg) ............... 645 (293)

Maintenance Data

Service Information

Compression Pressure, Minimum, psi (bar) ............... 120 (8.27)
Normal Operating Oil Pressure, psi (bar) ............... 30.0-45.0 (2.06-3.10)
Minimum Idle Oil Pressure, psi (bar) ............... 15.0 (1.03)
Coolant Thermostat Opening Temperature, F (C) ............... 170 (76.6)
Coolant Thermostat Full Open Temperature, F (C) ............... 190 (87.7)
Cooling System Pressure Cap Rating, psi (bar) ............... 7.0 (0.48)
Ignition Timing at High Idle, deg BTDC ............... 29.0-31.0
Ignition Timing at Low Idle, deg BTDC ............... 5.0
Carburetor Idle Speed Adjustment Needle ............... 1.25 to 1.50 turns
Carburetor High Speed Jet Adjustment Needle ............... 2.50 to 3.00 turns
Radiator Pressure Relief Cap Vent Rating, psi (bar) ............... 7.0 (0.48)
Valve Clearance (Intake), in (mm) ............... 0.027 (0.69)
Valve Clearance (Exhaust), in (mm) ............... 0.027 (0.69)

Engine Oil and Coolant

Engine Oil Type .................. SAE 30, SAE 10W, or 15W-40
API Service Classifications ......................... CC or CD
Engine Oil Capacity with Filter, qt (L) ............... 7.0 (6.6)
Engine Oil Capacity without Filter, qt (L) ............... 6.0 (5.7)
Cooling System Capacity, gal (L) ............... 5.5 (20.8)

Service Intervals

Change oil and filter ............... Every 100 hours
Inspect air cleaner ............... Every 50 hours
Service air cleaner ............... Every 250 hours
Valve clearance adjustment ............... Every 500 hours
Fuel system inspection ............... Every 1000 hours
Change coolant ............... Every 1000 hours
Spark plug replacement ............... Every 500 hours
Check ignition system ............... Every 500 hours

Service Specifications

Cylinder Bore Diameter, in (mm) ............... 3.5625-3.5640 (90.487-90.525)
Cylinder Bore Taper Wear Limit, in (mm) ............... 0.005 (0.127)
Cylinder Bore Out-of-Round Limit, in (mm) ............... 0.003 (0.076)
Cylinder Block Surface Flatness Limit, in (mm) ............... 0.003 (0.076)
Cylinder Head Surface Flatness Limit, in (mm) ............... 0.004 (0.101)
Crankshaft Main Journal Diameter, in (mm) ............... 2.7485-2.7495 (69.811-69.837)
Crankshaft Main Bearing Oil Clearance, in (mm) ............... 0.0015-0.0035 (0.038-0.088)
Crankshaft End Play, in (mm) ............... 0.004-0.008 (0.102-0.203)
Connecting Rod Journal Diameter, in (mm) ............... 2.2485-2.2495 (57.111-57.137)
Connecting Rod Bearing Oil Clearance, in (mm) ............... 0.0015-0.0030 (0.038-0.076)
Connecting Rod Side Play, in (mm) ............... 0.007-0.013 (0.177-0.330)
Piston-to-Cylinder Sleeve Clearance, in (mm) ............... 0.0035-0.0040 (0.088-0.101)
Piston Pin Diameter (Standard), in (mm) ............... 1.000 (25.40)
Piston Pin Fit in Piston Boss, in (mm) ............... 0.0001-0.0003 (0.002-0.007)
Piston Pin Fit in Rod Bushing, in (mm) ............... 0.0003-0.0007 (0.007-0.017)
Top Ring Groove Clearance, in (mm) ............... 0.0020-0.0040 (0.050-0.101)
Second Ring Groove Clearance, in (mm) ............... 0.0015-0.0035 (0.038-0.088)
Oil Ring Groove Clearance, in (mm) ............... 0.0015-0.0030 (0.038-0.076)
Top Ring End Gap, in (mm) ............... 0.010-0.020 (0.254-0.508)
Second Ring End Gap, in (mm) ............... 0.010-0.020 (0.254-0.508)
Oil Ring End Gap, in (mm) ............... 0.015-0.030 (0.381-0.762)
Intake Valve Head Diameter, in (mm) ............... 1.500 (38.10)
Exhaust Valve Head Diameter, in (mm) ............... 1.375 (34.92)
Intake Valve Guide Inner Diameter, in (mm) ............... 0.374 (9.50)
Exhaust Valve Guide Inner Diameter, in (mm) ............... 0.374 (9.50)
Intake Valve Stem Diameter, in (mm) ............... 0.3715-0.3725 (9.436-9.461)
Exhaust Valve Stem Diameter, in (mm) ............... 0.3705-0.3715 (9.410-9.436)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0015-0.0035 (0.038-0.088)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0025-0.0045 (0.063-0.114)
Valve Face Angle Profile, deg ............... 45.0
Valve Seat Angle Profile, degr ............... 45.0
Valve Spring Free Length, in (mm) ............... 2.125 (53.97)
Intake Valve Seat Width Range, in (mm) ............... 0.062-0.093 (1.574-2.362)
Exhaust Valve Seat Width Range, in (mm) ............... 0.062-0.093 (1.574-2.362)
Rocker Arm Shaft Outside Diameter, in (mm) ............... 0.873-0.874 (22.17-22.19)
Camshaft Journal Diameter (Number 1), in (mm) ............... 1.997-1.998 (50.72-50.74)
Camshaft Journal Diameter (Number 2), in (mm) ............... 1.934-1.935 (49.12-49.14)
Camshaft Journal Diameter (Number 3), in (mm) ............... 1.872-1.873 (47.54-47.57)
Camshaft Journal Diameter (Number 4), in (mm) ............... 1.810-1.811 (45.97-46.00)
Camshaft Bearing Oil Clearance, in (mm) ............... 0.0015-0.0040 (0.038-0.101)
Camshaft End Play, in (mm) ............... 0.003-0.007 (0.076-0.177)
Camshaft Valve Lift (Intake), in (mm) ............... 0.375 (9.52)
Camshaft Valve Lift (Exhaust), in (mm) ............... 0.375 (9.52)
Timing Gear Backlash Clearance, in (mm) ............... 0.002-0.006 (0.050-0.152)

Tightening Torques

Cylinder Head Bolts, lb-ft (Nm) ............... 90 (122)
Main Bearing Cap Bolts, lb-ft (Nm) ............... 80 (108)
Connecting Rod Cap Nuts, lb-ft (Nm) ............... 50 (68)
Flywheel to Crankshaft Bolts, lb-ft (Nm) ............... 65 (88)
Crankshaft Pulley Damper Bolt, lb-ft (Nm) ............... 110 (149)
Camshaft Thrust Plate Bolts, lb-ft (Nm) ............... 15 (20)
Rocker Arm Shaft Bracket Bolts, lb-ft (Nm) ............... 30 (41)
Manifold to Cylinder Head Bolts, lb-ft (Nm) ............... 25 (34)
Oil Pan Perimeter Drain Bolts, lb-ft (Nm) ............... 12 (16)
Oil Pan Large Drain Plug, lb-ft (Nm) ............... 40 (54)
Timing Gear Case Cover Bolts, lb-ft (Nm) ............... 18 (24)
Water Pump to Block Studs, lb-ft (Nm) ............... 20 (27)
Spark Plug Threads, lb-ft (Nm) ............... 25 (34)
Distributor Base Clamp Lock Bolt, lb-ft (Nm) ............... 15 (20)
Oil Pump Screen Cover Assembly, lb-ft (Nm) ............... 15 (20)
Flywheel Housing Rim Bolts, lb-ft (Nm) ............... 45 (61)
Valve Rocker Arm Cover Nuts, lb-ft (Nm) ............... 8 (11)
Fuel Pump Mounting Stud Flange, lb-ft (Nm) ............... 15 (20)
Carburetor Stud Mounting Nuts, lb-ft (Nm) ............... 18 (24)
Governor Housing Frame Bolts, lb-ft (Nm) ............... 20 (27)
Thermostat Housing Top Cover Bolts, lb-ft (Nm) ............... 20 (27)
Starter Motor Mounting Bracket Bolts, lb-ft (Nm) ............... 45 (61)
Alternator Pivoting Adjusting Pivot Bolt, lb-ft (Nm) ............... 30 (41)
Alternator Tensioner Locking Bolt, lb-ft (Nm) ............... 18 (24)
Fan Blade Assembly to Water Pump Hub, lb-ft (Nm) ............... 15 (20)
Crankcase Breather Tube Bracket Bolt, lb-ft (Nm) ............... 10 (14)
Ignition Coil Frame U-Bolt Shell Screws, lb-ft (Nm) ............... 5 (6)
Carburetor Fuel Inlet Line Flare Nut, lb-ft (Nm) ............... 12 (16)
Carburetor Air Inlet Clamping Ring Bolt, lb-ft (Nm) ............... 5 (6)

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• International Engines Specs
  
• International C175 Specs
  
• International C263 Specs
  
• International C291 Specs
  
• International C301 Specs
  

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