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Continental Y91 Engine

General Technical Data

Engine Specifications

Engine Model ............... Continental Y91
Engine Type ............... 4-cycle inline 4-cylinder side-valve L-head liquid-cooled gasoline
Number of Cylinders ............... 4
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 2.88 (73.02)
Engine Stroke, in (mm) ............... 3.50 (88.90)
Displacement, cu.in (L) ............... 90.89 (1.49)
SAE Horsepower Rating, hp (kW) ............... 13.22 (9.86)
Maximum Brake Power, hp (kW) ............... 36.0 (26.8) at 3000 rpm
Rated Engine Speed, rpm ............... 1500-2400
Peak Torque ............... 64.0 lb-ft (86.8 Nm) at 1600 rpm
Idle Speed ............... 450-550 rpm
Compression Ratio ............... 6.1:1
Firing Order ............... 1-3-4-2
Main Bearing Quantity ............... 3 main journal inserts
Camshaft Drive Type ............... Helical gear train system
Cylinder Block Type ............... Monoblock cast iron
Cylinder Head Type ............... Flathead cast iron detachable
Lubrication System ............... Full-pressure gear-driven assembly
Oil Pump Type ............... Internal gear-driven
Oil Filter Type ............... Bypass spin-on or replaceable element replaceable unit
Cooling System ............... Liquid-cooled thermo-syphon or centrifugal circulation pump
Water Pump Type ............... Belt-driven centrifugal impeller
Air Cleaner Type ............... Oil bath or dry cartridge assembly
Starting System ............... Electric starter motor or manual hand crank option
Electrical System ............... 6V or 12V direct current ground setup

Fuel System

Carburetor Manufacturer ............... Marvel-Schebler or Zenith alternative units
Carburetor Type ............... Updraft single barrel variant design
Fuel Induction Method ............... Naturally aspirated draw atmospheric induction
Fuel Delivery Pressure, psi (kPa) ............... 1.5-3.5 (10.3-24.1)
Fuel Pump Type ............... Mechanical diaphragm driven via camshaft eccentric lobe
Governor System Type ............... Mechanical flyweight velocity sensing device
Governor Speed Regulation ............... 3-5 percent internal mechanical variation
Fuel Grade Compatibility ............... Low lead gasoline or liquefied petroleum gas
Intake Manifold Material ............... Cast iron integrated setup with exhaust preheater chamber
Choke Control Mechanism ............... Manual cable operation or automatic thermal linkage

Dimensions and Weight

Overall Length, in (mm) ............... 22.1 (560)
Overall Width, in (mm) ............... 16.3 (415)
Overall Height, in (mm) ............... 24.5 (625)
Dry Weight, lbs (kg) ............... 290 (131.5)

Maintenance Data

Service Information

Compression Pressure, psi (kPa) ............... 90.0-110.0 (620.5-758.4)
Oil Pressure at Rated Speed, psi (kPa) ............... 30.0-45.0 (206.8-310.2)
Oil Pressure at Idle Speed, psi (kPa) ............... 7.0-10.0 (48.3-68.9)
Maximum Oil Temperature, F (C) ............... 210.0 (98.9)
Thermostat Opening Temperature, F (C) ............... 160.0 (71.1)
Thermostat Full Open Temperature, F (C) ............... 180.0 (82.2)
Spark Plug Gap, in (mm) ............... 0.025 (0.635)
Breaker Point Gap, in (mm) ............... 0.020 (0.508)
Intake Valve Lash, Cold, in (mm) ............... 0.012 (0.305)
Exhaust Valve Lash, Cold, in (mm) ............... 0.012 (0.305)

Engine Oil and Coolant

Engine Oil Type .................. SAE 30, SAE 10W-30
API Service Classifications ......................... MS/CD
Engine Oil Capacity, qt (L) ............... 4.00 (3.78)
Cooling System Capacity, qt (L) ............... 6.50 (6.15)

Service Intervals

Change engine oil ............... Every 100 hours
Replace oil filter ............... Every 100 hours
Clean fuel filter ............... Every 250 hours
Change coolant ............... Every 500 hours
Valve-lash adjustment ............... Every 250 hours
Check fuel system ............... Every 500 hours
Replace spark plug ............... Every 500 hours
Compression test ............... Every 500 hours
Belt inspection ............... Every 100 hours

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ............... 2.8750-2.8760 (73.025-73.050)
Cylinder Bore Out of Round (Maximum), in (mm) ............... 0.0010 (0.025)
Cylinder Bore Taper (Maximum), in (mm) ............... 0.0020 (0.051)
Main Journal Diameter (Number 1), in (mm) ............... 1.7475-1.7485 (44.387-44.412)
Main Journal Diameter (Number 2), in (mm) ............... 1.7475-1.7485 (44.387-44.412)
Main Journal Diameter (Number 3), in (mm) ............... 1.7475-1.7485 (44.387-44.412)
Main Bearing Clearance, in (mm) ............... 0.0012-0.0029 (0.030-0.074)
Crankshaft End Play, in (mm) ............... 0.0040-0.0070 (0.102-0.178)
Connecting Rod Journal Diameter, in (mm) ............... 1.4990-1.5000 (38.075-38.100)
Connecting Rod Bearing Clearance, in (mm) ............... 0.0010-0.0023 (0.025-0.058)
Connecting Rod Side Clearance, in (mm) ............... 0.0040-0.0090 (0.102-0.229)
Piston to Cylinder Bore Clearance, in (mm) ............... 0.0020-0.0025 (0.051-0.064)
Piston Pin Diameter, in (mm) ............... 0.6873-0.6876 (17.457-17.465)
Piston Pin to Con Rod Bushing Clearance, in (mm) ............... 0.0001-0.0004 (0.002-0.010)
Piston Pin to Piston Pin Bore Clearance, in (mm) ............... 0.0001-0.0003 (0.002-0.008)
Top Ring Groove Width, in (mm) ............... 0.0950-0.0960 (2.413-2.438)
Second Ring Groove Width, in (mm) ............... 0.0950-0.0960 (2.413-2.438)
Oil Ring Groove Width, in (mm) ............... 0.2510-0.2520 (6.375-6.401)
Top Ring Side Clearance, in (mm) ............... 0.0015-0.0030 (0.038-0.076)
Second Ring Side Clearance, in (mm) ............... 0.0015-0.0030 (0.038-0.076)
Oil Ring Side Clearance, in (mm) ............... 0.0010-0.0025 (0.025-0.064)
Top Ring End Gap, in (mm) ............... 0.0070-0.0150 (0.178-0.381)
Second Ring End Gap, in (mm) ............... 0.0070-0.0150 (0.178-0.381)
Oil Ring End Gap, in (mm) ............... 0.0070-0.0150 (0.178-0.381)
Cylinder Head Flatness Deflection Over Block, in (mm) ............... 0.0030 (0.076)
Cylinder Block Deck Surface Flatness, in (mm) ............... 0.0030 (0.076)
Intake Valve Head Diameter, in (mm) ............... 1.156 (29.362)
Exhaust Valve Head Diameter, in (mm) ............... 1.015 (25.781)
Intake Valve Port Diameter, in (mm) ............... 1.000 (25.400)
Exhaust Valve Port Diameter, in (mm) ............... 0.875 (22.225)
Valve Stem Outer Diameter, in (mm) ............... 0.311 (7.899)
Valve Guide Inside Diameter, in (mm) ............... 0.3125 (7.938)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0015-0.0032 (0.038-0.081)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0025-0.0042 (0.064-0.107)
Valve Seat Angle, deg ............... 45.0
Valve Face Angle, deg ............... 45.0
Camshaft Journal Diameter (Number 1), in (mm) ............... 1.3730-1.3740 (34.874-34.900)
Camshaft Journal Diameter (Number 2), in (mm) ............... 1.3730-1.3740 (34.874-34.900)
Camshaft Journal Diameter (Number 3), in (mm) ............... 1.2480-1.2490 (31.699-31.725)
Camshaft Bearing Clearance, in (mm) ............... 0.0015-0.0030 (0.038-0.076)
Cam Lobe Height (Intake), in (mm) ............... 0.250 (6.350)
Cam Lobe Height (Exhaust), in (mm) ............... 0.250 (6.350)
Camshaft End Play, in (mm) ............... 0.0030-0.0060 (0.076-0.152)

Tightening Torques

Cylinder Head Bolts, lb-ft (Nm) ............... 35.0-40.0 (47.5-54.2)
Connecting Rod Cap Nuts, lb-ft (Nm) ............... 22.0-25.0 (29.8-33.9)
Main Bearing Cap Bolts, lb-ft (Nm) ............... 55.0-60.0 (74.6-81.3)
Flywheel to Crankshaft Bolts, lb-ft (Nm) ............... 35.0-40.0 (47.5-54.2)
Flywheel Housing Mounting Studs, lb-ft (Nm) ............... 25.0-30.0 (33.9-40.7)
Camshaft Thrust Plate Screws, lb-ft (Nm) ............... 15.0-18.0 (20.3-24.4)
Timing Gear Cover Fasteners, lb-ft (Nm) ............... 10.0-14.0 (13.6-19.0)
Oil Pan Sump Bolts, lb-ft (Nm) ............... 10.0-12.0 (13.6-16.3)
Oil Pan Drain Plug, lb-ft (Nm) ............... 25.0-30.0 (33.9-40.7)
Intake Manifold Assembly Bolts, lb-ft (Nm) ............... 15.0-18.0 (20.3-24.4)
Exhaust Manifold Assembly Bolts, lb-ft (Nm) ............... 15.0-18.0 (20.3-24.4)
Water Pump Mounting Screws, lb-ft (Nm) ............... 12.0-15.0 (16.3-20.3)
Spark Plug Base, lb-ft (Nm) ............... 25.0-30.0 (33.9-40.7)
Distributor Clamp Lock Bolt, lb-ft (Nm) ............... 12.0-15.0 (16.3-20.3)
Oil Pump Assembly Fasteners, lb-ft (Nm) ............... 15.0-18.0 (20.3-24.4)
Valve Cover Inspection Plate Nuts, lb-ft (Nm) ............... 6.0-8.0 (8.1-10.8)
Governor Housing Attachment Caps, lb-ft (Nm) ............... 12.0-15.0 (16.3-20.3)
Generator Alternator Main Fastener, lb-ft (Nm) ............... 25.0-30.0 (33.9-40.7)
Crankshaft Front Pulley Screw, lb-ft (Nm) ............... 60.0-70.0 (81.3-94.9)
Fuel Pump Mechanical Arm Cap, lb-ft (Nm) ............... 12.0-15.0 (16.3-20.3)

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