International D350 Specifications
| Engine Model: International Harvester D350 |
| Engine Type: 4-stroke in-line 4-cylinder naturally aspirated liquid-cooled diesel |
| Total Displacement: 350 cu.in (5.73 L) |
| Rated Engine Power: 66 Hp (49.2 kW) at 1550 rpm |
| Fuel System Type: Direct injection |
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The International Harvester D350 is a
4-cylinder, liquid-cooled diesel engine from the D-series family.
Produced during the mid-1950s, this power unit served as the diesel
option for the Farmall 600 and International 650 standard tread
tractors. The engine displaces 350 cubic inches, achieved through a
long-stroke configuration favoring torque development at low engine
speeds. An oil bath air cleaner provides filtration in dusty
agricultural environments without requiring disposable paper elements.
The D350 operates at a governed speed of 1550 rpm with a wide idle
range, a design choice matching the torque characteristics of drawbar
and belt pulley work.
This engine uses direct injection and mechanical governing, predating
electronic controls and common rail systems. The D350 shares its bore
and stroke dimensions with other International Harvester engines of the
era, including the gasoline-fueled versions offered alongside the diesel
in the 1956 tractor lineup. The engine succeeded the D-335 in earlier
models and was replaced by the D-370 in later International 650 tractors
after the brief 1956 production run.
Engine Type: 4-cylinder, 4-stroke, liquid-cooled diesel, naturally
aspirated
Displacement: 5.735 L (5735 cc / 350 cu.in)
Bore x Stroke: 114.3 mm x 139.7 mm (4.50 in x 5.50 in)
Compression Ratio: 15.6:1
Combustion System: Direct injection
Aspiration: Naturally aspirated (no turbocharger)
Valvetrain: OHV (Overhead Valve), 2 valves per cylinder, 8 valves total
Net Power: 49.2 kW (66 hp) at 1550 rpm
Drawbar Power (installed, SAE): 31.7 kW (42.6 hp) at 1550 rpm
Belt PTO Power (SAE): 34.6 kW (46.4 hp) at 1550 rpm
Maximum Torque: 350 Nm (258 lb-ft) at 1100 rpm
Rated Engine Speed: 1550 rpm
Low Idle Speed: 500 rpm
High Idle Speed (no-load, governed): 1690 rpm
The cylinder block is manufactured from cast iron with a monobloc
construction. Four cylinder bores are machined directly into the parent
metal. The block uses a siamese bore configuration where each cylinder
shares a common wall with the adjacent cylinder, reducing overall engine
length. The crankcase features a deep skirt design extending below the
crankshaft centerline. Five main bearing bulkheads support the
crankshaft.
The water jacket surrounds the upper portion of each cylinder bore. Cast
oil galleries supply lubricant to the main bearings and camshaft
bearings. The engine uses a replaceable cartridge-type oil filter. The
block incorporates the mounting provisions for the oil bath air cleaner,
a design common to International Harvester diesel engines of this era.
The cylinder head is a single-piece cast iron component. Each cylinder
receives two valves: one intake valve and one exhaust valve, arranged in
a parallel valve layout. The valve train is an overhead valve (OHV)
configuration with pushrods and rocker arms. The camshaft is located in
the cylinder block, not the cylinder head. Valve stem seals are not used
on engines of this vintage; valve guides are machined directly into the
cylinder head casting.
The combustion chamber is formed by a bowl in the piston crown. The
cylinder head incorporates an intake port designed to generate swirl for
air-fuel mixing. Valve clearance adjustment uses a screw-and-locknut
arrangement on the rocker arms. The cylinder head gasket is an
asbestos-compound construction, original to the 1950s manufacturing
period.
The fuel system is a mechanical direct injection design. An in-line
injection pump (International Harvester or Bosch design) mounts to the
side of the timing gear case and delivers fuel to each cylinder in the
1-3-4-2 firing order. The injection pump incorporates a mechanical
centrifugal governor controlling both idle and maximum engine speeds. A
manual stop lever permits mechanical fuel shutoff.
Steel injection lines route individually to each injection nozzle. The
fuel lift pump is a mechanically actuated diaphragm type. An oil bath
air cleaner precedes the intake manifold, using an oil reservoir to
capture dust particles. The primary fuel filter is a replaceable
cartridge type mounted on the engine. No water separator is fitted on
original D350 engines. A hand primer lever on the lift pump permits
manual bleeding of air.
The lubrication system uses a gear-type oil pump driven from the
camshaft gear. The pump draws oil through a wire mesh suction strainer
positioned at the bottom of the oil pan. Oil passes through a
replaceable cartridge-type full-flow filter mounted on the engine block.
A pressure relief valve in the oil pump regulates maximum system
pressure.
The system lacks piston cooling jets, as the naturally aspirated
configuration generates lower thermal loads than modern turbocharged
diesel engines. Oil pressure at rated speed measures 0.28-0.41 MPa
(40-60 psi). A mechanical oil pressure gauge is standard equipment. Oil
capacity including the filter is 10.4 L (11.0 qt). The engine uses SAE
30 or SAE 15W-40 diesel-grade oil, with viscosity selection based on
ambient temperature.
The cooling system is pressurized and liquid-cooled. A belt-driven
centrifugal water pump circulates coolant through the cylinder block
water jacket, cylinder head, and radiator. The fan is belt-driven
directly from the water pump pulley. A wax-pellet thermostat, mounted in
a housing on the cylinder head, regulates coolant temperature. A bypass
circuit permits coolant circulation within the engine when the
thermostat remains closed.
Coolant capacity for the engine and radiator system is 34.1 L (36.0 qt).
The specified coolant is an ethylene glycol base antifreeze with a
concentration of 30-40% for freeze protection. A removable pressure cap
relieves excess pressure at 0.7 bar (10 psi). The water pump uses a
packed gland or mechanical seal depending on production date.
Aspiration: Natural aspiration without turbocharger. Air filtration uses
an oil bath air cleaner, a multi-stage design passing intake air through
an oil reservoir to trap dust. The oil bath cleaner requires periodic
cleaning and oil replacement rather than disposable filter elements.
Combustion System: Direct injection with bowl-in-piston. The piston uses
three rings: two compression rings and one oil ring.
Electrical System: 12 V negative ground. Starter motor power rating is
2.5-3.0 kW. Charging system uses a belt-driven generator (DC type) with
an external voltage regulator. The generator output is 20-30 A depending
on the installation.
PTO Operation: The engine drives a belt pulley (PTO) for stationary
applications including sawmills, grain elevators, and irrigation pumps.
Belt PTO power is 34.6 kW (46.4 hp) at 1550 rpm.
Length (flywheel to front pulley): 760 mm (29.9 in).
Width (overall, exhaust manifold to injection pump): 610 mm (24.0 in).
Height (oil pan rail to rocker cover): 710 mm (28.0 in).
Dry Weight (basic engine, no flywheel, no starter, no generator): 410 kg
(904 lb).
Engine Oil Change Interval: 100 hours under normal agricultural duty.
Engine Oil Capacity (including filter): 10.4 L (11.0 qt)
Engine Oil Grade (ambient above 5°C / 41°F): SAE 30, API CC or CD.
Engine Oil Grade (ambient below 5°C / 41°F): SAE 10W-30 or SAE 10W.
Engine Oil Pressure at Rated Speed: 0.28-0.41 MPa (40-60 psi)
Engine Oil Pressure at Low Idle (minimum, hot engine): 0.07 MPa (10 psi)
Coolant Capacity (system total, engine + radiator): 34.1 L (36.0 qt)
Coolant Specification: Ethylene glycol base antifreeze, 30-40%
concentration.
Oil Bath Air Cleaner Service Interval: Clean oil reservoir every 50
hours.
Fuel Filter Replacement Interval: 200 hours.
Valve Clearance (Cold Engine, Intake): 0.30 mm (0.012 in).
Valve Clearance (Cold Engine, Exhaust): 0.41 mm (0.016 in).
Valve Clearance Inspection Interval: 250 hours.
Injection Timing (static): 24-26 deg BTDC at No. 1 cylinder.
Injector Nozzle Opening Pressure: 12.0-12.5 MPa (1740-1810 psi).
Compression Pressure (standard): 2.8-3.2 MPa (406-464 psi) at cranking
speed.
Compression Pressure Variation Between Cylinders: 0.21 MPa (30 psi)
difference.
Drive Belt Tension: Deflection of 12-15 mm (0.47-0.59 in) under 10 kg
(22 lb) force.
Idle Speed Adjustment (low): 500 rpm via idle stop screw.
Idle Speed Adjustment (high, governed): 1690 rpm.
Cylinder Head Bolts (Stage 1): 50 Nm (37 lb-ft)
Cylinder Head Bolts (Stage 2): 90 Nm (66 lb-ft)
Cylinder Head Bolts (Stage 3): 120 Nm (89 lb-ft)
Connecting Rod Cap Nuts: 90 Nm (66 lb-ft)
Main Bearing Cap Bolts: 130 Nm (96 lb-ft)
Flywheel Bolts (to crankshaft flange): 135 Nm (100 lb-ft)
Flywheel Housing Bolts (to block): 65 Nm (48 lb-ft)
Camshaft Drive Gear Nut: 150 Nm (111 lb-ft)
Rocker Arm Shaft Bracket Bolts: 35 Nm (26 lb-ft)
Rocker Arm Adjusting Lock Nut: 18 Nm (13 lb-ft)
Valve Cover Nuts: 10 Nm (7 lb-ft)
Injection Pump Mounting Nuts (to timing case): 45 Nm (33 lb-ft)
Injection Pump Drive Gear Nut: 80 Nm (59 lb-ft)
Injection Line Fittings (pump end): 25 Nm (18 lb-ft)
Injection Line Fittings (nozzle end): 25 Nm (18 lb-ft)
Injector Hold-Down Clamp Nut: 35 Nm (26 lb-ft)
Crankshaft Pulley Bolt (center): 200 Nm (148 lb-ft)
Oil Pan Bolts: 14 Nm (10 lb-ft)
Oil Pan Drain Plug: 45 Nm (33 lb-ft)
Water Pump Mounting Bolts: 25 Nm (18 lb-ft)
Thermostat Housing Bolts: 20 Nm (15 lb-ft)
Starter Motor Mounting Bolts: 50 Nm (37 lb-ft)
Generator Mounting Bolts (pivot): 25 Nm (18 lb-ft)
Exhaust Manifold Nuts: 40 Nm (30 lb-ft)
Intake Manifold Bolts (oil bath air cleaner mount): 30 Nm (22 lb-ft)
Engine Mount Bracket Bolts (to block): 80 Nm (59 lb-ft)
Oil Bath Air Cleaner Mounting Bolts: 20 Nm (15 lb-ft)
Farmall 600 (1956): Standard tread tractor. Five-plow rating. Diesel
version uses the D350 engine. Drawbar power 31.7 kW (42.6 hp), belt PTO
power 34.6 kW (46.4 hp). Produced only in 1956.
International 650 (1956): Successor to the Farmall 600. Standard tread
and row-crop configurations. The D350 was the diesel engine option for
the 1956 model year. The D-370 replaced the D350 in later 650
production.
Agricultural Equipment: Belt pulley drives for stationary applications
including sawmills, grain elevators, shellers, silage blowers, and
irrigation pumps. The wide power band from 1100 rpm torque peak to 1550
rpm rated speed suits variable load belt work.
Industrial Power Units: Stationary power for rock crushers (small
capacity). Hydraulic pump drives for industrial equipment. Generator
drives (30-40 kW range at 1550 rpm).
Custom Restoration: The D350 engine is sought for restoration of 1956
Farmall 600 and International 650 tractors. Engine parts
interchangeability with the D-335 (gasoline version) is limited, as the
diesel uses different cylinder heads, pistons, and fuel system
components.
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