International C175 Specifications
| Engine Model: International Harvester C175 |
| Engine Type: 4-stroke in-line 4-cylinder liquid-cooled gasoline |
| Total Displacement: 175 cu.in (2.9 L) |
| Rated Engine Power: 65-68 Hp (48-51 kW) at 2400 rpm |
| Fuel System Type: Updraft carburetor |
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The International C175 is a 2.9-liter,
naturally aspirated inline-four gasoline engine produced by
International Harvester during the late 1960s through the mid-1970s.
This engine belongs to the C-series family, which includes the smaller
C-153 and C-157 variants, with the C-175 representing a larger-bore
configuration designed for increased torque output in heavier utility
applications. The engine was developed as a modern replacement for older
six-cylinder power units, offering improved power density and a more
compact footprint for tractor engine bays.
The C-175 features an overhead valve (OHV) valvetrain with pushrods, a
robust cast iron cylinder block, and replaceable wet cylinder liners - a
design choice that facilitates easier overhaul and extended service life
in demanding agricultural and industrial environments. Unlike
high-performance automotive engines of its era, the C-175 was calibrated
for sustained low-to-mid range operation under varying loads, with a
mechanical governor maintaining consistent engine speed for PTO-driven
implements.
The engine served as the gasoline option in several International
tractor models, including the International 574 and 674 utility
tractors, the 2400B industrial tractor, and the T-7C crawler tractor.
Its production spanned from approximately 1969 to 1974, after which the
gasoline variant was discontinued in favor of diesel power units.
Engine Type: Inline-4, four-stroke, naturally aspirated, gasoline.
Displacement: 175 cu.in (2.9 L).
Bore: 3.625 in (92.1 mm).
Stroke: 4.250 in (108.0 mm).
Compression Ratio: 7.5:1.
Firing Order: 1-3-4-2.
Gross Horsepower: 65-68 hp (48-51 kW) at 2,400 rpm.
PTO Horsepower: 52-60 hp (39-45 kW) depending on tractor model.
Maximum Torque: 155-165 lb-ft (210-224 Nm) at 1,400-1,600 rpm.
Rated Engine Speed: 2,400 rpm (some applications 2,500 rpm governed).
Governed Speed Range: Idle to 2,500 rpm maximum no-load.
The cylinder block is constructed from high-strength cast iron, a
material selection providing excellent rigidity and vibration damping
for sustained heavy-load operation. The block features an open-deck
design with three main bearing supports for the crankshaft, a
configuration adequate for the engine's modest power output and
operating speed range.
The most distinctive design element is the replaceable wet sleeve
cylinder liner arrangement. Each cylinder receives an individual liner
pressed into the block, with the lower portion of each liner sealed by
rubber O-rings to prevent coolant migration into the crankcase. This wet
sleeve design permits complete engine overhaul without removing the
block from the chassis, a significant advantage for agricultural and
industrial users where downtime directly impacts productivity.
The block incorporates cast passages for coolant circulation around the
full circumference of each liner, promoting uniform thermal expansion
and reducing distortion. A side-mounted distributor drive housing is
cast into the right side of the block, while the left side features
provisions for the mechanical fuel pump and oil filter base.
The cylinder head is a single-piece cast iron unit with a cross-flow
design, locating the intake and exhaust ports on opposite sides of the
head to improve thermal efficiency and breathing. The head incorporates
wedge-shaped combustion chambers with the valves positioned at an angle
to promote swirl and turbulence for complete fuel mixture combustion.
The valvetrain operates on an overhead valve (OHV) configuration with
pushrods and rocker arms. The camshaft is located within the cylinder
block, driven by a gear train from the crankshaft, and actuates the
valves through solid steel pushrods and stamped steel rocker arms. Each
cylinder receives two valves - one intake and one exhaust - with the
valves arranged in a single row along the cylinder head centerline.
The valves are constructed from one-piece steel alloy with hardened tips
and chrome-plated stems for wear resistance. Intake valve diameter
measures 1.531 in (38.9 mm), while the exhaust valve diameter is 1.281
in (32.5 mm). Valve stem diameter is 0.341 in (8.66 mm) for both intake
and exhaust valves.
The valve seat inserts are pressed into the cylinder head and machined
to a 45-degree face angle. Valve springs are single-coil type with
dampers to control harmonics at higher engine speeds. The rocker arm
assembly is supported on a single shaft running the length of the
cylinder head, with individual adjusters provided for each valve to
permit precise lash settings.
The fuel system employs an updraft carburetor mounted on the left side
of the engine, drawing air upward through the carburetor and into a cast
aluminum intake manifold. Carburetor suppliers included Zenith and
Marvel-Schebler, depending on the specific tractor model and production
date. The updraft configuration positions the float bowl below the
throttle body, reducing the risk of fuel leakage onto hot engine
surfaces. The carburetor incorporates an idle circuit, main metering
circuit, power enrichment circuit, and an accelerator pump for
responsive throttle operation.
A mechanical gear-driven flyweight governor is integrated into the fuel
system to maintain constant engine speed under varying loads. The
governor operates by sensing engine speed through a gear-driven shaft
and adjusting the throttle plate position through a linkage system. As
load increases and engine speed begins to drop, centrifugal force on the
governor weights decreases, allowing a spring to open the throttle
further.
Conversely, when load decreases, the weights overcome spring tension and
close the throttle. This arrangement maintains the engine at the
operator-selected governed speed regardless of load variations, a
critical requirement for PTO-driven implements such as mowers, balers,
and rotary tillers.
A mechanical fuel pump, mounted on the cylinder block and actuated by an
eccentric lobe on the camshaft, draws fuel from the tank and delivers it
to the carburetor float bowl at low pressure, 3-5 psi (21-34 kPa). A
replaceable in-line fuel filter is located between the tank and the fuel
pump.
The lubrication system is a fully pressurized, wet-sump design with a
gear-type oil pump mounted inside the oil pan. The oil pump drives
directly from the distributor shaft, which in turn receives rotation
from the camshaft gear. The pump draws oil through a screened pickup
tube and delivers it to a full-flow spin-on type oil filter mounted on
the left side of the cylinder block. From the filter, oil circulates
through main oil galleries drilled longitudinally through the block,
supplying the crankshaft main bearings, connecting rod bearings,
camshaft bearings, and hydraulic valve lifters.
The system includes a pressure relief valve calibrated to open at
approximately 45-50 psi (310-345 kPa) to prevent over-pressurization
during cold starts. Normal operating oil pressure ranges from 25-40 psi
(172-276 kPa) at rated speed, with a minimum acceptable pressure of 10
psi (69 kPa) at hot idle. Oil capacity with filter change is 6.0 US
quarts (5.7 L). The recommended oil viscosity depends on ambient
operating temperature, with SAE 10W-30 for moderate climates and SAE 30
for sustained high-temperature operation.
The cooling system is a pressurized, thermostatically controlled liquid
cooling setup with a belt-driven centrifugal water pump. Coolant
circulates from the radiator lower tank through the water pump, into the
cylinder block water jacket, upward through the cylinder head, and
returns to the radiator upper tank through a cast outlet.
The system incorporates a wax-type thermostat with a nominal opening
temperature of 180°F (82°C). The thermostat remains closed during
warm-up, bypassing coolant directly back to the water pump inlet for
rapid engine warm-up.
Coolant capacity varies by chassis application. For tractor
installations, the combined engine and radiator capacity is 14.0 US
quarts (13.2 L). Pressurized to 7 psi (48 kPa), the cooling system
raises the boiling point of the coolant to provide a safety margin under
heavy load conditions. A belt-driven fan, mounted on the water pump hub,
draws air through the radiator core.
The fan is shrouded to maximize airflow efficiency at low engine speeds
common in PTO operation. An optional kerosene or fuel heater manifold
was available for cold-weather starting, routing exhaust gases around
the intake manifold to warm the incoming air-fuel mixture.
| Ignition and Electrical System |
Ignition System: The engine employs a battery-coil distributor ignition
system. A Delco-Remy distributor, mounted on the right side of the
cylinder block and driven by the camshaft, distributes high-voltage
current to the spark plugs through suppression-type ignition wires. The
distributor housing contains a four-lobe cam, breaker points, a
condenser, and a centrifugal advance mechanism. A vacuum advance unit,
connected to the intake manifold, provides additional timing advance
under light load conditions to improve fuel economy. Base ignition
timing is set to 3 degrees before top dead center (BTDC) at idle, with
total mechanical advance reaching 28 degrees BTDC at governed speed.
Electrical System: The engine uses a 12-volt electrical system with
negative ground. A belt-driven alternator or DC generator, depending on
production year, supplies charging current to the battery. A starter
motor mounted on the flywheel housing engages the ring gear through a
solenoid-operated drive mechanism.
Governor System: A mechanical flyweight governor, mounted at the front
of the engine and driven by the camshaft gear, provides speed
regulation. The governor housing contains weighted arms that rotate
against spring tension. An external lever linkage connects the governor
to both the throttle control and the carburetor throttle plate.
Crankcase Ventilation: A road draft tube system vents crankcase gases to
the atmosphere, drawing fresh air through the oil fill cap and
exhausting blow-by gases through a tube directed downward below the
engine.
Overall length from the front cover to the flywheel housing mounting
face is 30 in (762 mm). Width, measured across the cylinder head and
intake manifold, is 22 in (559 mm), while height from the oil pan rail
to the top of the valve cover is 28 in (711 mm). The bare engine dry
weight, including the cylinder block, crankshaft, connecting rods,
pistons, cylinder head, and valvetrain components, is 480 lb (218 kg).
The fully dressed engine weight, including the intake and exhaust
manifolds, carburetor, distributor, starter motor, alternator, water
pump, and flywheel, ranges from 525-550 lb (238-249 kg) depending on
installed accessories.
Engine Oil Capacity: With filter change, 6.0 US quarts (5.7 L).
Recommended SAE viscosity grades: 10W-30 for ambient temperatures above
0°F (-18°C), 5W-20 for cold climates. Coolant Capacity: 14.0 US quarts
(13.2 L) for engine and radiator combined. Use ethylene glycol
antifreeze mixed with clean water to the freeze protection required for
local conditions. Carburetor Adjustment: Idle mixture screw set to 1.5
turns from lightly seated as initial setting. Idle speed adjustment
screw set to 500-600 rpm with no governor load.
Valve Lash Adjustment: Required as part of scheduled maintenance.
Clearances are measured with the engine at operating temperature
(170-190°F / 77-88°C), engine stopped. Intake Valve Lash: 0.014 in (0.36
mm). Exhaust Valve Lash: 0.014 in (0.36 mm). Air Cleaner Service: Oil
bath air cleaner requires cleaning of the oil cup and replacement of the
sump oil every 100 operating hours under normal conditions, more
frequently in dusty environments. Drive Belt Tension:
Generator/alternator and water pump belt should deflect 0.5-0.75 in
(13-19 mm) under moderate thumb pressure at the mid-point of the longest
span.
Spark Plugs: Champion N-9Y or equivalent. Spark plug gap is 0.025 in
(0.64 mm). Replacement interval is 300 operating hours. Breaker Point
Gap: 0.020 in (0.51 mm) for new points, with dwell angle of 31-34
degrees. Ignition Timing: 3 degrees BTDC at idle speed (500 rpm). Total
advance at governed speed reaches 28 degrees BTDC. Cylinder Liner
Protrusion: Wet sleeves require 0.001-0.003 in (0.03-0.08 mm) protrusion
above the block deck surface for proper head gasket sealing.
Cylinder Head Bolts (Stage 1): 30 lb-ft (41 Nm).
Cylinder Head Bolts (Stage 2): 60 lb-ft (81 Nm).
Cylinder Head Bolts (Stage 3): 80-90 lb-ft (108-122 Nm).
Connecting Rod Cap Bolts (Stage 1): 20 lb-ft (27 Nm).
Connecting Rod Cap Bolts (Stage 2): 45-50 lb-ft (61-68 Nm).
Main Bearing Cap Bolts: 75-85 lb-ft (102-115 Nm).
Flywheel Bolts: 55-65 lb-ft (75-88 Nm).
Rocker Arm Shaft Bracket Bolts: 25-30 lb-ft (34-41 Nm).
Camshaft Thrust Plate Bolts: 15-18 lb-ft (20-24 Nm).
Intake Manifold Nuts: 25-30 lb-ft (34-41 Nm).
Exhaust Manifold Nuts: 20-25 lb-ft (27-34 Nm).
Spark Plugs: 20-25 lb-ft (27-34 Nm).
Oil Pan Bolts: 12-15 lb-ft (16-20 Nm).
Valve Cover Bolts: 4-6 lb-ft (5-8 Nm).
Water Pump Mounting Bolts: 20-25 lb-ft (27-34 Nm).
Carburetor Flange Nuts: 15-18 lb-ft (20-24 Nm).
Crankshaft Pulley Bolt: 150-170 lb-ft (203-230 Nm).
Starter Motor Mounting Bolts: 30-35 lb-ft (41-47 Nm).
The International C175 engine was primarily installed in utility
tractors, industrial equipment, and crawler tractors manufactured by
International Harvester from approximately 1969 to 1974.
International 574 Utility Tractor (1971-1976): This 52-55 PTO hp tractor
represented the primary application for the C175 in the European and
North American markets. The gasoline version offered an alternative to
the diesel D-239 engine for operators preferring gasoline fuel
availability or lower initial cost.
International 674 Utility Tractor (1971-1976): The larger sibling to the
574, producing approximately 60 PTO hp with the C175 engine. This model
included a heavier chassis and larger tires for row-crop applications.
International 2400B Industrial Tractor (1970-1974): A heavy-duty
industrial version of the 574 used for loader and backhoe applications.
The C-175 provided 60 gross hp at 2,400 rpm with hydrostatic
transmission option.
International T-7C Crawler Tractor (1969-1974): This gasoline-powered
crawler produced 54 gross hp (50 net hp) at 2,500 rpm governed speed.
The T-7C replaced the older T-6 Series 62 and featured a 4-speed
constant mesh transmission with power reverser. Production of the
gasoline T-7C ceased in 1974 without a direct replacement.
International 350 Utility (late production): Some late-production 350
utility tractors received the C-175 engine as an upgrade from the
smaller C-153.
International 454 and 464 Tractors: These smaller utility tractors used
the C-157 or C-200 engines, with the C-175 appearing as an intermediate
option in certain production runs.
International 2500A and 2500B Industrial Tractors: Heavy-duty industrial
models utilizing the C-175 engine for loader applications.
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