Model A Ford Specifications

CAPACITIES

Cooling System: 3 gallons
Gasoline tank: 1928-29, 10 gallons / 1930-31, 11 gallons
Engine oil pan: 5 quarts
Transmission: 1-1/2 pints
Steering gear: 7-3/4 oz.
Differential: 2-1/4 pints

ENGINE

Rated horsepower: 24.03 SAE
Brake Horsepower: 40 HP @ 2200 rpm (Model AF 28 @ 2000 rpm)
Firing order: 1-2-4-3
Compression ratio: 4.22 to 1
Compression pressure: A-6050A head, 76 PSI; A-6050B head, 110 PSI; B-6050 head, 90 PSI
Piston displacement: 200.5 cu. inch
Bore: 3.876″ (Model AF: 3.050″)
Stroke: 4.250
Torque: 128 ft/lbs. at 1000 rpm
Cylinder offset from crankshaft centerline: 1/8″
Crankshaft to camshaft centerline: 4.155″

CYLINDER BLOCK

Length: 19-5/16″
Width: 7-13/16″
Height: 11-1/2″
Bore: 3.875 to 3.876″
Bottom of block to camshaft bore centerline: 2.876 to 2.878″
Top of block to camshaft bore centerline: 8.624 to 8.627″
Valve lifter and guide bore: .594 to .5945″ diameter
Distributor drive gear bore: .9356 to .9375″ diameter
Cylinder outside diameter: 4-3/8″ (wall thickness 1/4″)
Flatness of the top of block: .003 to .005″
Cylinder bore perpendicular to top of block: .001 to .002″

CRANKSHAFT

Material: Special Ford carbon manganese steel
Weight: 28 lbs.
Length: 26 inches
Diameter: 1.624″ main bearings, 1.499″ crank pins
Length of main bearings: Front and center, 2″; rear, 3″
Length of crank pins: 1-5/8″
Crank pin taper and roundness: ,0005 to .001″
Total main bearings surface: 11-1/2 sq. inches
Rear flange thickness: 3/8″
Crankshaft gear: 25 spiral teeth
End clearance: .004 to .007″
Main bearing clearance: .001″
Crankshaft straightness: .0005 to .001″
Main bearing cap torque: 55-65 ft. lbs.
Distance from top surface cross-member to crankshaft centerline: 2-33/64″

CONNECTING RODS

Material: Steel Forging
Weight: 1 lb., 6 oz.
Balance weight: 552 grams +/- 1 gram, crank end; 198 grams +/- 1 gram, pin end
Length: 7-1/2″ center to center
Crankshaft bearing: 1-1/2 diameter, 1-5/8″ wide
Piston pin bearing: 1″ diameter, 1-5/8″ wide
Bearing side clearance: .008 t0 .012″
Pin side clearance: .040 to .053″ between pin bosses
Piston pin clearance: .0005′”
Crank shaft clearance: .001″
Bearing cap bolt torque: 40-50 ft. lbs.
Connecting rod assembled with oil clippers toward camshaft.

PISTONS

Displacement: 200.5 cu. inches
Material: aluminum
Weight: 1 lb. 1-7/8 oz. (476.8 grams)
Variance in weight of pistons: +/- 2 grams
Weight with rings installed: 1 lb. 4-1/2 oz. (581.2 grams)
Weight with rings and pin: 1 lb.  8-3/4 oz. (701.7 grams)
Diameter: 3.8745″ (Bore: 3.875 )
Length: 3-29/32″‘
Piston skirt: .001″ smaller at the top than the bottom of skirt
Piston pin hole: .9996 to .9998′” diameter
Piston pin diameter: 1.0001 to 1.0004″
Pin length: 3.536 10 3.546”
Compression Height (t0p of piston to pin centerline): 1-29/32″
Variation in piston compression height: .003 to .005″‘
Piston pin bushing: I.D.  .991″, O.D. 1.0675″, Length 1.593″
Pin fit in rod bushing: .0003″ max.
Pin fit in piston: .0002 to .0005″ shrink fir (not normally used today)
Pin bore parallel to head to piston: +/- .001″
Piston fit in cylinder: .002″ max.
Ring diameter: same as piston, 3.875″ stock
Ring groove: depth, 7/32″‘; grove width-upper two. 1/8″; lower. 5/32″
Ring taper: .001″ narrower at top than the bottom
Ring clearance in groove: .001 to .002″
Ring end gap: top, .012 to .015″; middle, .010 to .012″: lower, .008 to .010″

CAMSHAFT

shaft diameter: 7/8″‘
Bearing diameter: 1.560″
Block bore diameter: 1.561″
Bearing clearance (max.): .003″
Bearing length: Front 1-3/4″; center, 2″; rear 1″; 4th (1928), 7/8″
Lift of cam: .303″ (Model B: .339″ exhaust; .334″ intake)
Duration: 236°
Lobe center angle: 113-1/2″
End play spring tension: approximately 35 lbs.
Timing gear mounting flange: 2-5/16′” diameter 5/16″ thick
Camshaft material: Special Ford carbon manganese steel
Camshaft gear: Bakelized material
No. of gear teeth: 50
Camshaft gear type: spiral teeth
Gear backlash: .003 to .oo5″
Gear rotation speed: 1/2 of crankshaft
Camshaft straightness: .0005 to .001″
Variation in eccentricity of pitch diameter of gear teeth: .0015″
Variation in maintaining center distance of mating gear: +/- .001″
Gear tolerance in regular spacing of teeth: 0.0″

VALVES

Lilf .287″ with .015″ clearance
Scat angle: 45°
Seat Width: 3/32″
Stem diameter: .311″ Valve length: 5.677″
Head diameter: 1.537″
Valve opening diameter: 1-3/8″
Port diameter: 1-3/8″
Clearance. exhaust valves in guides: .002″
Clearance. intake valves in guides: .001 to .0015″
Valve lifter clearance: .010 to .013″
Lifter diameter clearance: .0015″
Valve guides: I.D.-.3135″; O.D.-.5938″; length-2.125″ (early 2.375″)
Valve spring: O.D.-1.022″; free length-2-15/16″; Compressed lcngth-2.250″ (57-64 lbs.); tension (closed) -34 to 38 lbs.
Valve lifter: A-6500A (used with “A” camshaft), length – 2.486″  head diameter – 1.117″; B-6500 (used with “B” camshaft), length 2.158″ head diameter – 1.187″
Valve timing:
Model A:
Intake opens 7-1/2° before TDC (Top Dead Center)
Intake closes 48-1/2° after BDC (Bottom Dead Center)
Exhaust opens 51-1/2° before BDC
Exhaust closes 4-1/2° after TDC
Model B:
Intake opens 8° before TDC
Intake closes 56° after BDC
Exhaust opens 56° before BDC
Exhaust closes 8° after TDC

HEAD

1928 head: 4.3 to 1 compression ratio, 47.3 HP. 242cc displacement: Compression in individual cylinders: 80, 85, 83, 82 PSI
1930 Head: 4.1 compression ratio, 44.3 HP, 258cc displacement: Compression in individual cylinders: 77, 79, 82, 79 PSI
Nominal listed compression: A-6050A, 75 lbs.; A-6050B, 110 lbs.; B-6050, 90 lbs.
Head nut torque: 55 ft./lbs.

SPARK PLUGS

(sec also Ignition)
type: Champion 3X
Thread: 7/8-18
Torque: 25 Nibs.

IGNITION

Distributor rotor revolves: counter-clockwise
Point gap: .018 to .020”
Point Spring tension: 16 to 18 oz.
Condenser capacity: .20 10 .25 MFD
Spark plugs: Champion 3X, 7/8 x 18 thread
Spark plug gap: .035″ (6050 A head), .030″
(B-6050 head), .025” (A-6050B head)
Yellow wire ignition circuit, 12 gage. All other wiring except high tension circuit is 16 gage.
Cam shaft to bearing clearance: .001 to .002″
Spark control manual advance: 20° (28° crankshaft travel)
Rotor end cap to distributor body terminal: .020″
Ignition current: .62 amps at 6.2 volts – engine at 1500 rpm; 4 amps at 6.2 volts (engine stopped)

CARBURETOR

Throat size: 1″
Float level: 5/8” below upper body machined surface (Model B, 33/64″ below body machined surface)
Main jet: .037″ LD. (No. 63 drill bit)
Cap Jet: .037″ I.D.
Compensator jet: .035” I.D. (No. 65 drill bit)
Idling jet: .021″ I.D. (No. 75 drill bit)

OIL PUMP & LUBRICATION

Type: Pump. splash. gravity feed
Crankshaft bearing: gravity feed
Connecting rods: splash
Camsl1af1 bearings: gravity feed
Oil pump type: gear
Oil pump capacity: 9 pints/min at 1300 rpm
Oil Pump pressure: 80-100 lbs.
Oil pump shall: 1/2” diameter (in 5/8″ bore). except I 928’s with 9/16” bore and undercut shaft
(Model B used 5/8” bore with undercut shaft.)
Oil pump gear teeth to housing clearance: .001 to .002″
Housing cover to face of gears clearance: .001 to .002″
Drive gear to camshaft gear clearance: .003 to .005″

FLYWHEEL

Weight: 63 lbs.  4 oz. (Model B: 52 to 55 lbs.)
Balance: Within .15 inch/oz.
Ring gear shoulder diameter: 12.470”
Model Ring gear outside diameter: 12.2″
No. of ring gear teeth: 112
Ring gear to starter drive ratio: 11.2 to 1
Flywheel bolt torque: 65 ft./lbs.
Pilot bearing holeis concentric with crankshaft flange shoulder within .002 TIR (total indicator reading)
Clutch mounting surface and clutch disc surface must run true to crankshaft within .005″: TIR
Clutch mounting shoulder diameter must be concentric with crankshaft flange diameter within .005″ TIR

CLUTCH

Material: Molded asbestos composition
Pressure Plate weight: 15 lbs.
Clutch disc weight 2-1/12 lbs.
Clutch pressure: 1100 lbs.
Foot petal pressure: 30 lbs.
Clutch facings: 9″ diameter. 9/64″ thick
Inside diameter: 5-3/4”
Total acting surface area: 75 sq. inches
Clutch pedal clearance (free play) 3/4″ for multiple disc: 1″ for single
Clutch release bearing hub: 2.065” diameter
Clutch throw-out bearing: Bower 2065

COOLING SYSTEM

Water pump shafi: 5/8” diameter
Water pump shaft end play: .006 10 .0 10″
Fan belt: Gates #700
Fan belt width: 5/8′”
Fan blade length: 16″
Fan cooling surface: 374 sq. inches
Fan speed: 1-1/2 time engine rpm
Fan delivers about 855 cfm at 1000 rpm, about 24 mph
Radiator hose: Upper 2″ diameter. 6-1/4″ long ( 1928-29), 8″ long ( 1930-31 ); Lower (two pieces), 1-3/4” diameter, 2-3/4” long
4-blade fan: At 1000 rpm (fan). 62% increase in air flow, 82% increase in HP absorbed: at 2000 rpm, 55% increase in airflow, 47% increase in HP absorbed.

RADIATOR

1928 Manufactured: f’ord
Tubes: Round, 1/4″ diameter
Number or tubes: 94 in 4 rows. staggered at 25°
Number of fins: 117
Cooling surface: 375 sq. inches

1929 Manufacturers: Flintlock, Long, McCord
Tubes: Round, 1/4″ diameter
Number of tubes: Flintlock. 100, 4 rows, alternate rows in line; McCord, 87, 5 rows. alternate rows in line; Long, same as 1928 Ford

1930-31 Manufacturer: Ford
Tube dimensions: 5/32 X 1/2″ flat, angled 15″
Number of tubes: 102. 3 rows in line
Number of fins: 132
1929 Commercial: 140 tubes, 4 rows, slanted in line.
1930-31 Commercial: 136 tubes. 4 rows slanted in line.

BATTERY

Terminal grounded: Positive
Voltal!e: 6 volt
Capacity: 80 ampere hours, starting capacity 98 amps
Numbers of cells: 3
Number of plates: 13 per cell
Charging rate: 10 to 12 amps @ 1500 rpm

STARTER

Type or drive: Bendix (except early 1928)
Terminal grounded: Positive
Rotation: Counter-Clockwise (viewed from commutator end)
Armature: 21 segments
Bush spring tension: 35 to 40 oz.

Starter Date
Normal
Running Free
Locked
Text Data

Torque
3 | 0 | 15 | 4 | 8 | 12

RPM
1500 | 4000 | 0 | 1000 | 540 | 220

Volts
5 | 6 | 3.2 | 4.85 | 4.15 | 3.60

Amps
175 | 50 | 550 | 225 | 360 | 475

GENERATOR

Type: Two pole
Voltage Regulation: Fixed control
Brushcs: three (one adjustable)
Armature bearings: 1929 mid 1930 ball. front and rear; after mid 1930, ball front. bushing rear
Armature speed: 1-1/2 of engine speed
Armature length: 7-9/16″ (1928 to April 1930)–uses 1-5/32″ wide pulley, 7-21/32″ (after April 1930) uses 7/8″ wide pulley
Maximum normal charging rate: 12 amperes@ armature 1600 rpm (car speed. 25 mph)
Cutout closes: about 9 mph
Cutout opens: about 8 mph
Contact gap: .015 10 .020″
Core gap: .010 ( contacts closed)
Brush spring tension: 35 to 40 oz. each
Field Coils: 100 turns of #17 cooper wire
Armature.: 14 coils. each with 6 turns of #17 cooper wire
Commutator: 28 cooper segments
Field Current draw: 6.3 amps at 7 volts. generator (motoring) draws 5.75 amps at 7 volts
Maximum current: 18 10 22 amps at 6 volts
Motoring freely: 5 amps at 6 volts
Field test: 5.2 amps at 6 volts

LIGHTS

Headlights: 21-21 CP, double contact base, Mazda 1110 (Some 32-31 CP starting in Feb. 1929), 32-32 CP from Nov. 1930 to end of product
Cowl: 3 CP. single contact. Mazda 63
Parking: 3 CP. single contact. Mazda 63
Tail: 3 CP. single contact, Mazda 63
Stop: 21 CP. single contact, Mazda 1129
Instrument Panel: 3 CP. single contact, Mazda 63
Dome: 3 CP, single contact, Mazda 63
Commercial dome (cargo): 15 CP. single contact, Mazda 87

TRANSMISSION

Gear and shall material: chromium alloy steel
Gear ratios: High, 1 to 1 (100%); second. 6.9 to 1 (53.8%): low, 8.75 to 1 (32.04%) reverse, (26.7%)
Bearings: main shall front (ball) 1208: main shall rear (ball) 1306: counter shaft short. Bower J 241256; long, Bower J 241246: pilot bearing SKF 6203 2RSJ
Transmission case length: 6.560 to 6.565″
Case front bearing hole: 3.1497 to 3.1507″ diameter
Case rear bearing hole: 2.835 to 2.836″

DRIVE SHAFT

Length of full spline: 2.5″
Spline minor diameter: .901 to .911 ”
Spline outer diameter: 1.090 to 1.091″
Pinion bearing torque: 15 to 20 ft./lbs.

AXLE, REAR
Type: Three quarter floating
Material: Special Ford Carbon manganese steel
Gear Ratio (Gear 1ee1h: Ring-pinion): 3.78:1 (34-9);
Early 1928’s: 3.7:1 (37-10); Trucks -4, 11:1 (37-9); Approximately 10,000 1928-29 – Roadsters – 3.54:1 (39-11)
Pinon bearing: Double taper roller type
Bearing: Timken 28516
Bearing Cup: Timken 28317 –
Ring gear: 8.4″ pitch diameter, 1-3/16” wide teeth
Axle shaft: 1-1 /8″ diameter; 1.128 to 1.130″ at wheel bearing
Dimension from housing flange to bearing shoulder in axle housing: Before 1929: 1.370 to 1.372″, After: 1.365 to 1.367″
Rear wheel bearing: O.D. of axle housing race – 2.061 to 2.0635” I.D. of Wheel Hub: 3.188 to 3.190” – Max. wear 3.185”
Axle and drive shaft: CR 10926
Rear axle seal: CR 20112, Victor 49024
Differential Lubricant: 600W or 160W

AXLE, FRONT

Materinl: Chrome alloy forging
Tensile strength: 125,000 to 145.000 PSI
Caster: 5° (forward tilt)
Toe In: 1/16” +/- 1/32″- Camber: 1-13/16”
Spindle bolt (king pin): diameter: .8125” +/- .0005″; length: 5-5/16″
Spindle bolt bearing: Timken T83, Nice 5699
Spindle bolt to bearing clearance: .001 to .002″
Front wheel bearings:
Inner bearing: Timken 15118; Cup: Timken 15250
Outer bearing: Timken 09074; Cup: Timken 09196

SPRINGS

Material: chromium alloy steel
Front spring leaf width: 1-3/4″
Front spring free length: 30-12/16″ to 30-15/16″
Rear spring free width: 2-1/4″
Rear spring free length: Tudor, Fordor – 38-7/8″ to 39″; Phaeton, Roadster, Coupes – 39-7/8″ to 39-1/2″

STEERING

Turning radius: 17 ft. (34 ft. diameter)
Steering gear ratio: 11-1/4 to 1 ( 1928-29); 13 to 1 ( 1930-31)
Steering wheel diameter: 17-1/2″ ( 1928-29); 17″ ( 1930-31)
Pitman arm length (hole center to ball center): 6-7/8″
Ball end angle to shaft: 14″
Sector shaft bearing clearance: .001 to .002″
Bearings: 1928-29 7-tooth. Timken T83; 1930-31 2-tooth gear cup
Timken 13 C; bearing Timken 3571

TIRES

Size: 1928-29, 4.75 x 21: 1930-31, 4.75 x 19
Recommended tire pressure: 35 lbs.
Station Wagon: 5.00 x 21 or 19, pressure 40 lbs.
Tread width 56 inches

BRAKES, SERVICE
Percentage of braking power: Front wheels, 40%: rear wheels 60%
Diameter of drums: 11″ +/- .010″
Drum width: 1-3/4″
Width or brake shoes:  1-1/2″
Length of brake shoes: 14″
Brake shoe lining thickness: 3/16″
Brake shoe lining material: woven wire and asbestos composition
Total brake shoe surface area: 168 sq. inches
Brake rod length: 51-7/16″ to 51-1/2″

BRAKES, EMERGENCY

Diameter of drum: 9-5/8″
Width or brake shoe:  1″
Thickness or lining: 3/16″
Length of brake shoe: 18-3/4′”
Material: Woven wire and asbestos composition
Total brake shoe surface area: 57-1/2 sq. inches
Total braking area of six brake system, 225-1/2 sq. inches

RADIUS ROD (front)

Ball felt size: 3/4 x 1-3/4 x 3″

ROAD CLEARANCE

9 inches

GAS TANK

Steel thickness: .049 to .051″ (teme plated)
Capacity: 1928-29, 10 gallons; 1930-31, 11 gallons

EXHAUST

Exhaust pipe: 2″ I.D.
Tail pipe: 1-5/8” I.D.

WHEELS

Material: Steel
Diameter: 1928-29 – 21″;   1930-31 – 19″
Rim: Drop center type: width, 1928-29 – 2-3/4″; 1930-31 – 3″
Number of spokes: 30 ( 1/4″ diameter)

WHEELBASE

103-1/2″ (passenger car and light commercial)