Old Ford Tractor Specifications and Data

By: John Smith of Old Ford Tractors

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Misc Specifications and Data

Overall Length115"118.875"121.4"121.8"132"132.4"
Overall Width64.75"71.7"
Front Tread Width48"-76"52"-76"8.3"-16.3"
Rear Tread Width48"-76"52"-76"56"-84"
Ground Clearance21"27.2"27.9"
Approx Shipping Weight2410#2550#2750#2850#3100#3184#
Engine Type4 cyl. "L" head4 cyl. OHV
Displacement119.7 ci.134 ci.172 ci.134 ci.172 ci.
Compression Ratio6.50:16.60:16.75:16.60:16.75:1
Firing Order1-2-4-3
Idle Speed400 RPM450-475 RPM
Maximum RPM (no load)2000 RPM2200 RPM2400 RPM2200 RPM2400 RPM
SleevesCast Alloy IronCast Iron
PistonsAluminum Alloy
Cooling System TypePressure
FanFour or Six BladeThree Blade
Initial Timing @ 475 rpm4º BTDC (more info 1)8º   BTDC5º BTDC8º   BTDC5º BTDC
Advance @ 2000 RPM18º (more info 2)29º to 31º26º to 28º29º to 31º26º to 28º
Point Gap0.015 (more info 3).024 to .026
Spark Plug size14MM
Spark Plug Gap.025 to .028
Generator TypeTwo Brush, shunt wound
Generator Capacity20 amps, 140w20 amps, 160w20 amps, 140w
Battery6 volt positive ground

Misc Specifications and Data Info

- 9N, 2N, 8N prior to serial number 263844..... 0º TDC
- 9N, 2N, 8N prior to serial number 263844..... 25º BTDC.
3 - 8N side distributor after serial number 263843......025".


Model or Series9N2N8NNAA600700800900501601701801901
Fuel Capacity10 gallons11 gallons14 gallons13 gallons17 gallons
Cooling System12 quarts15 quarts
Crankcase Capacity6 quarts5 quarts (with filter change)
Transmission Capacity- 4 speed5 Gallons (more info)5 q6.5 q5 q6.5 q
Transmission Capacity- 5 speedno info provided8 q8.5 q
Differential CapacitySee note 18.5 q8 q11.5 q8 q11.5 q8 q
Hydraulic System CapacitySee note 18 q9 q8 q9 q8 q
Steering Assembly CapacityN/A1 pt.
Air Filter Oil Cup Capacityapproximately 1.3 pints
Oil Pump GPMapproximately 3.4 GPM @ 1400 RPM
Water Pump GPMapproximately 16 GPM @ 1400 RPM
Thermostatopen @ 160º- open @ 180º
Pressure Capno info providedrelief valve opens @ .5 to 1.0 psi - pressure valve opens @ 3.5 to 4.5 psi

Capacities Info

Note 1 9N2N, and 8N has a common sump for the hydraulic oil which also provides lubrication to the transmission and differential.
NAA and Hundred series tractors have separate reservoirs for transmission lubricant, hydraulic fluid, and differential lubricant.


Model or Series9N2N8NNAA600700800900501601701801901
Crankshaft Journal Diameter- Main2.248" - 2.249"2.4974" - 2.4988"
Crankshaft End Play.002 - .006
Crankpin Diameter2.094"2.2978" - 2.2988"
Main Bearing Clearance.001 - .003.0007 - .0023
Connecting Rod Bearing Clearance.001 - .0035.002 - .0004
Connecting Rod Side Clearance.003 - .009
Piston Pin Diameter.7501 - .7504.9121 - .9123
Piston Pin Length2.837" - 2.092"
Pin Clearance in Rod and Piston.0001 - .0003
Connecting Rod Bushing I.D..9122 - .9125
Fitting New Piston in New Bore0.0015
Fitting Used Piston in New Bore0.002
Fitting Used Piston in Used Bore0.003
Piston Ring Side Clearance- top ring.002 - .0035
Piston Ring Side Clearance- second ring.0015 - .003 (134cid)  .002 - .0035 (172 cid)
Piston Ring Side Clearance- oil ring.0015 - .003 (134 cid)  .002 - .0035 (172 cid)
Camshaft Bearing Clearance.001 - .002.0015 - 0.0035
Camshaft Journal Diameter1.797"1.925" - 1.926"
Camshaft Gear Lash.002 - .006
Camshaft End Play.003 - .007
Camshaft Block Bore Diameter1.9275" - 1.9285"
Rocker Arm Support Journal Diameter.780 - .781
Rocker Arm Running Clearance.002 - .004
Valve Face Angle46º
Valve Seat Angle45º
Valve Seat Runout0.002
Valve Seat Width- intake.060 - .080
Valve Seat Width- exhaust .090 - .110
Valve Lash.014 - .016
Valve Cap-to-Stem End Clearance.002 - .004
Valve Guide Inside Diameter.3436 - .3444
Valve Stem-to-Guide Clearance.001 - .002
Valve Stem Diameter- intake/red0.3418
Valve Stem Diameter- intake/green0.3423
Valve Stem Diameter- exhaust/red0.3408
Valve Stem Diameter- exhaust/green0.3413
Valve Timing- Intake Opens @15º before T.D.C
Valve Timing- Intake Closes @35º after B.D.C
Valve Timing- Exhaust Opens @41º before B.D.C
Valve Timing- Exhaust Closes @15º after T.D.C
Valve Lift- Intake0.3553
Valve Lift- Exhaust0.337
Valve Rotators- exhaustFree spin
Valve Tappet Diameter.4989 - .4995
Valve Tappet Bore Clearance.0005 - .0021
Oil Pump Drive Shaft-to-Body Clearance.0015 - .0029
Oil Pump Driven Gear-to-Pin Clearance.001 - .002
Oil Pump Gear-to-Pump Body Side Clear..005 max.

Original Wheels and Tires

Model or SeriesFront TireRear Tire
8N  (note 1)4.00x1910x28
NAA (note 2)4.00x1910x28
600 Series5.50x1611x28
601 All Purpose Model5.50x1611x28
601 Special Utility Model5.50x1610x28
621 Special Utility Model5.50x1610x28
631 Special Utility Model5.50x1610x28
641 Special Utility Model5.50x1610x28
651 Special Utility Model5.50x1610x28
661 Special Utility Model5.50x1610x28
700 Series5.50x1611x28
800 Series6.00x1612x28
801 All Purpose Model6.00x1612x28
801 Special Utility Model5.50x1610x28
811 Special Utility Model5.50x1610x28
821 Special Utility Model5.50x1610x28
900 Series5.50x1611x28
901 Series5.50x1612x28

Original Wheels Info

1- 5.50x16 front tires optional
2- 5.50x16 front and 11x28 rear optional.

Tire Inflation Chart

Tire Size/PositionInflation PressureMax. Lbs. Load Per Wheel
10.00x28 4-ply rear16 psi1860
10.00x38 4-ply rear16 psi2155
11.00x28 4-ply rear14 psi2070
12.00x28 4-ply rear14 psi2430
12.00x38 4-ply rear14 psi2420
12.40x28 4-ply rear14 psi2070
13.00x24 4-ply rear14 psi2470
13.60x28 4-ply rear14 psi2430
14.00x24 4-ply rear16 psi3560
14.90x24 4-ply rear18 psi3125
14.90x28 4-ply rear14 psi2630
5.50x16 4-ply front28 psi1060
6.00x16 4-ply front20 psi755
6.50x16 6-ply front28 psi1050
7.50x16 8-ply front44 psi2390
9.00x16 8-ply front49 psi1620

Liquid Weight Chart

Tire SizeGals of WaterLbs. of Calcium ChlorideTotal Weight Added
9:00 x 10 front945120
5:50 x 16 front4.522.560
6:00 x 16 front5.22669
6:50 x 16 front5.929.579
7:50 x 16 front945120
10:00 x 28 rear24122324
10:00 x 38 rear31157416
11:00 x 28 rear32160426
12:00 x 28 rear39197525
12:00 x 38 rear51257685
13:00 x 24 rear44219584
13:00 x 28 rear49246648
13:60 x 28 rear39197525
14.90 x 24 rear44219584
14:90 x 28 rear49246648

Torque Specifications


Camshaft Thrust Plate to Cylinder Block10-16 ft.lbs.
Camshaft Gear to Camshaft45-50 ft.lbs.
Carb Throttle Body to Fuel Bowl36 in.lbs.
Connecting Rod Nuts45-50 ft.lbs.
Connecting Rod Pal Nuts3-4 ft.lbs.
Crankshaft Pulley to Crankshaft100-110 ft.lbs.
Cylinder Front Cover15-18 ft.lbs.
Cylinder Head Bolts65-70 ft.lbs.
Flywheel to Crankshaft75-85 ft.lbs.
Hydraulic Pump Gear Cover to Cylinder Block18-21 ft.lbs.
Main Bearing Cap Bolts95 -105 ft.lbs.
Manifolds to Cylinder Block40-50 ft.lbs.
Governor Cylinder Front Cover15-18 ft.lbs.
Oil Pan to Cylinder Block15-18 ft.lbs.
Oil Filter to Cylinder Block20-25 ft.lbs.
Oil Pump to Cylinder Block30-35 ft.lbs.
Oil Tubes to Oil Pump Cover Plate10-15 ft.lbs.
Rocker Arm Shaft Bolts45-50 ft.lbs.
Spark Plugs24-30 ft.lbs.
Valve Push Rod Chamber Cover20-30 in.lbs.
Valve Rocker Arm Cover8-10 ft.lbs.
Valve Rocker Arm Support to Cylinder Head4 5-50 ft.lbs.
Water Outlet Elbow8-10 ft.lbs.
Water Pump to Cylinder Block15-18 ft.lbs.
Throttle Body to Fuel Bowl36 in.lbs.
Governor Case to Front Cover6-10 ft.lbs.


Engine Adapter Plate Nuts25-30 ft.lbs.Rear Support Mounting Bolts35-40 ft.lbs.
Distributor Attaching Bolts20-30 ft.lbs.Servo #1 Cover Attaching Bolt20-25 ft.lbs.
Interlock Cover Attaching Bolts35-40 ft.lbs.Servo Actuating Lever Pin Nuts100-120 ft.lbs.
Lever Pin Retaining Bolt90-110 ft.lbs.Torque Limiting Clutch Mounting Bolts25-30 ft.lbs.
P.T.O. Bearing Retainer Nuts12-15 ft.lbs.Transmission Cover Attaching Bolts18-23 ft.lbs.
P.T.O. Hydraulic Fluid Line Fitting to Distributor10-12 ft.lbs.Valve Body Mounting Bolts5-8 ft.lbs.
Pump Mounting Bolts15-18 ft.lbs.

Front Axle

Axle Half to Center Axle Nut135-150 ft.lbs.Radius Rod to Transmission Housing Nut45-50 ft.lbs.
Center Axle Pin200 ft.lbs.Spindle Arm to Spindle Nut60-70 ft.lbs.
Radius Rod to Center Axle Nut75-135 ft.lbs.Support to Engine Nut135-150 ft.lbs.

Rear Axle

Axle Shaft Retainer or Final Drive Nuts130-150 ft.lbs.Lower Link Shaft Nut (inside)150 ft.lbs.
Axle to Center Housing Nuts55-65 ft.lbs.P.T.O. Shifter Plate40-55 ft.lbs.
Axle to Center Housing Studs40-45 ft.lbs.Pinion Retainer Bolts80-100 ft.lbs.
Center Housing to Transmission Housing40-50 ft.lbs.Relief Valve Plate Bolts35-45 ft.lbs.
Differential Case90-100 ft.lbs.Wheel Lug Nuts80 ft.lbs.
Drive Gear Bolts90-110 ft.lbs.Axle Nut450 ft.lbs.
Thrust Block Bolts25-30 ft.lbs.

Power Take Off

Belt Pulley Assembly to Center Housing Bolts35-40 ft.lbs.P.T.O. Cover Bolts35-40 ft.lbs.
Conversion to Center Housing Bolts40-50 ft.lbs.Shift Cover Nuts45 ft.lbs.
P.T.O. Conversion Cover Bolts40-50 ft.lbs.Shift Lever Studs40-45 ft.lbs.


Adapter to Steering Gear Housing20-25 ft.lbs.Steering Gear Housing to Transmission Housing60-70 ft.lbs.
Sector Shaft Cover Bolts25-30 ft.lbs.Steering Shaft Cover Retaining Screws25-30 ft.lbs.

Old Ford Tractor PTO Horsepower Ratings

ModelPTO Speed at Engine RPMHorsepower
9N727 @ 200023.6
8N ('47-'48)727 @ 200023.6
8N ('49-'52)727 @ 200026.2
Jubilee/NAA727 @ 200031.1
640- Gas727 @ 200031
640- LP727 @ 200028.4
660- Gas685 @ 200034.2
740- Gas727 @ 200031.6
850- LP685 @ 200039.5
860- Gas685 @ 200045.4
960- Gas685 @ 200046.3
621, 631, 641, 741- Gas727 @ 200033.6
651, 661- Gas685 @ 200035.8
821, 841, 941- Gas727 @ 200044.7
851, 861, 951, 961- Gas685 @ 200048.4
541D, 641D, 741D- Diesel727 @ 200031.8
821D, 841D, 941D- Diesel727 @ 200039.9
851D, 861D, 951D, 961D- Diesel685 @ 200042
841L- LP727 @ 200042
Select-O-Speed 671, 681, 771- Gas693 @ 200034.3
Select-O-Speed   671, 681, 771- Diesel693 @ 200031.6
Select-O-Speed   671, 681, 771- LP693 @ 200032.6
Select-O-Speed   871, 971- Gas693 @ 200046.2
Select-O-Speed   871, 881, 971, 981-Diesel693 @ 200041.4
Select-O-Speed   871, 881, 971, 981- LP693 @ 200043.6

Model 8N Operators Manual Data


Wheelbase 70 inches
Over-all length115 inches
Over-all height54 1/2 inches
Over-all width, normal tread64 3/4 inches

Tire Size

Front standard4.00 - 19 inches
optional6.00 - 16 inches
Rear standard11.2 - 28 inches
Tread width48 to 76 inches in 4-inch steps

Turning circle radius (with use of brakes)

Made by outer front wheel 8 feet
Made by tractor centerline at rear axle3 1/2 feet
Shipping weight (including gasoline, oil, water, tires
with air, operator not included)
2,410 lbs.
Drawbar Height 8 1/2 to 34 1/4 inches

Capacities - U.S. Measure

Fuel tank10 gals. total
Engine oil pan6 qts. with filter
Transmission, hydraulics 80w905 gals.
Cooling system12 qts.
Oil bath air cleaner1 pint

Tire Pressure

Rear12 lbs.
Front 26 lbs.


Type 4-cylinder "L" head
Maximum Drawbar HP. 2nd Gear23.16
Maximun belt horsepower at 2000 R.P.M.27.32
Rated speeds1500, 1750, and 2000 RPM.
Idle speed400-450 R.P.M.
Cylinder bore3.188 in.
Stroke3.75 in.
Piston displacement119.7 cu. in.
Torque 92 lbs ft. at 1500 rpm
Compression ratio6.50:1
SleevesDry type
RingsCompression (2) Oil (1)
Piston pinFull floating
Rod bearingsReplaceable shell-type
Main bearingsReplaceable shell-type
CrankshaftCast steel, static and dynamic balanced
Compression psi at cranking speed90 psi minimum

Valve tappet clearance

Intake.010 - .012 cold
Exhaust .014 - .016 cold
Main bearing diameter2.248 - 2.249 in.
Rod bearing diameter2.094 in.

Cylinder head

stud nuts 50-55 ft lb
bolts65-70 ft lb
Main cap bolts75-85 ft lb
Rod cap bolts 35-40 ft lb

Ignition System

Firing Order1-2-4-3
Initial Timing4 degrees before TDC
Maximum advance18 degrees
Side distributor .024 to .026 in
Front distributor.015 in
Spark plug gap.025 to .028 in.


TypeSingle up-draft
Make Marvel-Schebler
Idle fuel adjustment1 turn
Main fuel jet1 turn


Location In upper radiator hose
Starts to open160-l65 degrees F
Fully open190-200 degrees F

Electrical System

Generator 2-brush
Maximum output20 Amps
Charging voltage7.1 to 7.5 volts
Battery Type6-volt
GroundPositive (+)


Type Constantmesh
Number of speeds forward4


Type Single plate
Diameter9 in.
Release bearing (pre-lubricated)Ball bearing
Pedal free travel3/4 in.

Rear Axle

Ratio6.66 to 1


Type Internal expanding
Brake pedal free play3/4 in.

Steering Gear

TypeAutomotive ball nut
Ratio, turns of steering wheel for total travel of
pitman arms at 48 in. wheel tread
Steering wheel diameter18 in.

Hydraulic Control

Type Internal
Maximum pressure 1500-1700 psi
Pump TypeScotch Yoke piston
DriveDirect power take-off shaft
2000 engine R.P.M. Capacity 2.85 gals per min
1500 engine R.P.M2.15 gals per min
Control Manual and automatic
Oil supplyFrom transmission and differential

Power Take-off Adapter

Spline1 1/8 in.
PTO Speed (@1500 engine R.P.M.)545 R.P.M.

Tractor Performance

Maximum Drawbar H.P. 2nd Gear23.16
Rated Drawbar H.P. 2nd Gear (75% max.)17.37
Maximum belt horsepower at 2000 R.P.M 27.32
Rated belt horsepower (85% of max.)23.22

Model 9N-2N-8N Data Charts

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Thanks to John Smith of Old Ford Tractor for allowing us to use this information.