Dimensions & Weight
| MGB Dimensions & Weight Specification | ||
|---|---|---|
| Wheelbase: | 91 in | |
| Track - front: | 49.0 in | |
| Track - rear: | 49.25 in | |
| Overall length: | 153.2 in | |
| Overall width: | 59.9 in | |
| Overall height: | 49.4 in | |
| Ground clearance: | 4.2 in | |
| Turning circle: | 32 ft | |
| Curb (dry) weight: | 1962 | 2080 lbs |
| 1968 | 2220 lbs | |
| 1980 | 2335 lbs | |
| Test (wet) weight: | 1962 | 2400 lbs |
| 1968 | 2590 lbs | |
| 1980 | 2505 lbs | |
Chassis
Unit Construction body, welded steel constuction, front suspension on subframe.
Steering
Cam Gears, rack & pinion system.
| MGB Steering Specification | |
|---|---|
| Turning circle: Steering ratio: Turns lock-to-lock: Castor angle: Camber angle: Kingpin angle: Toe in: Grade of oil: |
32 ft (to car 410000, 06/1976) ? (from car 410001) 21.4:1 (as above) ? 2.9 (as above) 3.5 7° 1° 8° 0.1875 in SAE 90EP Hypoid |
Brakes
Disc brakes front, drum brakes rear.
| MGB Brakes Specification | |
|---|---|
|
Disk size front: Drum size rear: Parking brake: Method of operation: |
10.75 in 10 in Cable operated, rear Hydraulic, vacuum servo assisted as option to 1973, standard thereafter. Dual system some markets from '67. |
Suspension
Armstrong lever shocks at 4 corners, integral upper control arm at the front, linked to leaf spring retaining plate at the rear.
| MGB Suspension Specification | |
|---|---|
| Grade of oil: | 20wt motorcycle fork oil (approximate) |
Wheels
Either steel disc bolt-on with hubcaps, or Rudge type wire spoked. Late cars had painted steel wheels as option (Rubery Owen aka "Rostyle").
| MGB Wheel Specification | |
|---|---|
| For MkI, MkII-on: Rim size: Tyre Size: Tyre pressure: Wheel bolts: |
Wires 4J * 14, 5J * 14, 4.5J * 14 5,60 * 14, 165 * 14 (approx 175/70HR14 or 185/70HR14) 21 psi front, 24 psi rear (+4 for highway) 4 on 4-1/2" |
Engine
4 cylinder in line, pushrod, single cam.
High or low compression depending on market.
| MGB Engine Specification | |
|---|---|
|
Bore: Stroke: Cubic capacity: Main bearings: Oil pressure: Grade of oil: Sump Capacity: Firing Order: Compression ratio HC: Compression ratio LC: Compression HC: Compression LC: Valve size in/ex: Cam timing: Power output: |
80.26mm 88.90mm 1798cc 18G, 18GA - 3 18GB on - 5 ~70psi at 3000rpm ~50psi idle SAE 20W50 7.5 pints 1-3-4-2 18G - 8.8:1 18V - 9.0:1 8.0:1 18G - 160psi 18V - 170psi 130psi 18G, 18V 74 on - 39.8mm/34.1mm 18V to 74 - 41.3mm/34.1mm 18G - 16/56 51/21 18V - 20/52 55/17 See performance section in Library. |
Ignition Timing
Varies with Engine spec, see above.
| MGB Ignition Specification | |
|---|---|
|
Distributor points gap: Dwell: Spark plugs: Spark plug gap: |
0.015 in 60° NGK BP6ES or Champion N9YC 0.025 in (0.030 in or more with Sport coil) 0.035 in (after 1975) |
Carburetter Type
| MGB Carburetor Specification | |
|---|---|
| 1963 - 1971: 1972 - 1974: 1975 - 1980: |
Twin SU HS-4 Twin SU HIF-4 Single Zenith-Stromberg |
| Jet size, main: Needle & Springs: |
SU 0.090 in Zenith: 0.100 Various according to carburettor spec. |
Clutch
Borg & Beck type, single dry plate.
| MGB Clutch Specification | |
|---|---|
| Material: Number of springs: |
Ferodo Single Diaphragm |
Gearbox
Four speed manual, synchromesh on top three ratios to 1965, all synchro after. Electrical overdrive optional, standard from 1975. Borg Warner 35 automatic gearbox was also available 1967 to 1973.
| MGB Transmission Specification | ||||
|---|---|---|---|---|
| 18G-18GB (to Oct67) | 18GD-18V/780 (Nov67-Nov74) | 18V/797-18V/847 (Dec74-May76) | 18V/846-18V/893 (Jun76-) | |
| First: | 3.6363:1 | 3.440:1 | 3.036:1 | 3.333:1 |
| Second: | 2.2143:1 | 2.167:1 | ||
| Third: | 1.3736:1 | 1.382:1 | ||
| Third O/D: | 1.101:1 to 18GD, 1.133:1 18GF on | |||
| Top: | 1.00:1 | |||
| Top O/D: | 0.802:1 to 18GD, 0.82:1 18GF on | |||
| Reverse: | 4.7552:1 | 3.095:1 | ||
| Grade of oil: | SAE 20W50 (same as engine) | |||
| Capacity: | 4.5 pints, 4.7 pints, 6 pints. Add ~3 pints when O/D fitted | |||
Propellor Shaft
Open shaft, needle roller universal joint at each end with grease zerks.
Final Drive
Live axle, hypoid bevel gears. "Banjo" type to Jun-67, "Salisbury" type onwards. Open differential.
| MGB Differential Specification | ||||
|---|---|---|---|---|
| Ratio: | Manual: | 3.909:1 (all years) | ||
| Auto: | 3.7:1 | |||
| MGC: | Early manual: | 3.07 | ||
| Early auto & o/d: Late manual: | 3.307 | |||
| Late o/d: | 3.70 | |||
| MPH per 1000rpm: | Manual top: | 17.9 | ||
| Top O/D: | 22.1 | |||
| Auto: | 18.91 | |||
| Grade of oil: | SAE 90EP Hypoid | |||
| Capacity: | 1.5 pints | |||
Cooling System
Pressurised, thermostatic control, pump assisted. Water/antifreeze mix.
| MGB Cooling System Specification | ||||
|---|---|---|---|---|
| Capacity: | 12 pints | |||
| Cap Rating: | 1962-67 | 7 lbs | ||
| 1968-75 | 10 lbs | |||
| 1976 | 13 lbs | |||
| 1977-80 | 15 lbs | |||
Fuel System
Tank located at rear of car under boot (trunk) floor.
Pump SU points-type, attached to battery bracket on right hand side, in front of rear wheel, under body.
| MGB Fuel System Specification | ||||
|---|---|---|---|---|
| Tank capacity: | 12 gallons (?) | |||
| Pump pressure: | 2-4 psi (static) | |||
| Pump rate: | SU HP | 31.8 Lph | ||
| SU AUF 300/305 | 68.2 Lph | |||
MGB Production Data
For a more complete description of the VIN plate found on the dash and the engine number, and the meaning of the letters in those numbers, please read the MGB VIN FAQ article in the MG Experience Tech Library.
| Model Year |
1st Month |
Car Number (VIN) | Body Number | Engine Number | ||
|---|---|---|---|---|---|---|
| RD | GT | RD | GT | |||
| 1963 | 5/62 | 101 | MGB/101 | 18G/ /HL101 | ||
| 1964 | 8/63 | 19586 | MGB/26813 | 18GA/ /HL101 | ||
| 1965 | 10/64 | 48766 | ?? | 18GB/ /HL101 | ||
| 1966 | 10/65 | 71441(?) | 71933 | ?? | GBD/101 | 18GB/ /HL101 |
| 1967 | 11/66 | 108039 | ?? | ?? | ?? | 18GB/ /HL101 |
| 1968 | 10/67 | 138401 | 139472 | MGBU/101 | GBUD/500101 | 18GF/ /HL101 |
| 1969 | 10/68 | 158371 | 158233 | MGB/14588# | ?? | 18GH/ /HL101 |
| 1970 | 10/69 | 187211 | 187841 | MGBU/27359 | GBUD/510630 | 18GH/ /HL22209 18GJ/ /HL101 |
| 1971 | 9/70 | 219021 | 219335 | MGBU/300101 | GBUD/520235 | 18GK/ /HL101 |
| 1972 | 5/71 | 258001 | 258004 | MGBU/400101 | GBUD/620101 | 18V/584Z/L101 18V/585Z/L101(OD) |
| 1973 | 8/72 | 294251 | 296001 | MGBU/500101 | GBUD/720101 | 18V/672Z/L101 18V/673Z/L101(OD) |
| 1974 | 8/73 | 328101 | 328801 | MGBU/600101 | GBUD/820101 | 18V/672Z/L14891# 18V/673ZZ/L14891(OD)# |
| 1975 | 12/74 | 367901 | ?? | GU23T/7707 | ?? | 18V/797AE/L101 18V/798AE/L101(OD) |
| 1976 | 9/75 | 386601 | ?? | GU23T/50101 | ?? | 18V/801AE/L101 18V/802AE/L101(OD) |
| 1977 | 6/76 | 410001 | 410351 | GU23T/760000 | ?? | 18V/883AE/L101 18V/884AE/L101(OD) |
| 1978 | 9/77 | 447001 | ?? | GU23T/860000 | ?? | 18V/890AE/L101 18V/891AE/L101(OD) |
| 1979 | 6/78 | 471001 | ?? | GV23T/960000 | ?? | 18V/883AEL/29033# |
| 1980 | 6/79 | 501001 | ?? | GV23T/984080 | ?? | 18V/883AEL/43540# |
|
# These numbers are approximate. Thanks to Caroline Robinson (University Motors), Moss Motors, and Victoria British If you have any of the missing numbers please contact me! | ||||||
Detailed Specification
Under Construction - Incomplete
Usual disclaimers apply. It is wholly possible I have made typographical errors in the numbers below.
Make sure to double check the figures before doing any work and let me know if you find any errors so I can correct them.
Thanks, Skye N. (Webmaster)
| Engine | |
|---|---|
| ENGINE SPECIFICATION & DATA - 1798 c.c. TYPE 18G & 18GA | |
| Engine - General | |
| Type | 4 cylinder in line O.H.V. pushrod operated 18G or 18GA |
| Bore | 3.16 in. (80.26 mm.) |
| Stroke | 3.5 in. (89 mm.) |
| Cubic Capacity | 1789 c.c. (109.8 cu. in.) |
| Compression Radio : High C | 8.8 to 1 |
| Low C | 8.0 to 1 |
| Compression Pressure : High C | 160 lb./sq. in. (11.25 kg./cm2.) |
| Low C | 130 lb./sq. in. (9.15 kg./cm2.) |
| Torque : High C | 110 lb./ft. (15.2 kg.m.) at 3,000 r.p.m. |
| Low C | 105 lb./ft. (14.5 kg.m.) at 3,000 r.p.m. |
| Engine Idle Speed - Optimum | 500 r.p.m. |
| Firing Order | 1,3,4,2 |
| Location of No.1 Cylinder | Next to radiator. |
| Engine Mountings | 3 - one each side of the engine, one under the gearbox |
| Camshaft and Camshaft Bearing | |
| Camshaft Drive | From crankshaft by double roller chain |
| Camshaft Bearings | Three - white metal replaceable liners |
| Camshaft Journal diameter: | |
| Front | 1.78875 to 1.78925 in. (45.424 to 45.437 mm.) |
| Centre | 1.72875 to 1.72925 in. (43.910 to 43.923 mm.) |
| Rear | 1.62275 to 1.62325 in. (41.218 to 41.230 mm.) |
| Camshaft bearings internal diameter after reaming in position in block: |
|
| Front | 1.79025 to 1.79075 in. (45.472 to 45.485 mm.) |
| Centre | 1.73025 to 1.73075 in. (43.948 to 43.961 mm.) |
| Rear | 1.62425 to 1.62475 in. (41.256 to 41.269 mm.) |
| Diametrical clearance | .001 to .002 in. (.0254 to .0508 mm.) |
| End float | .003 to .007 in. (.076 to .178 mm.) |
| Cam lift | .250 in. (6.35 mm.) |
| Timing Chain | 3/8 in. (9.25 mm.) pitch by 52 pitches |
| End thrust | Taken by locating plate |
| Connecting Rods & Big & Little End Bearings | |
| Type | Angular split big end, split clamp small end |
| Length between centres | 6.5 in. (165.1 mm.) |
| Big end bearings - Type | Shell |
| Big end bearings - Material | Steel backed copper-lead |
| Big end bearings - Length | .995 to 1.005 in. (25.2 to 25.52 mm.) |
| Big end bearings - Clearance | .001 to .0027 in. (.0254 to .068 mm.) |
| Endfloat on crankpin | .008 to .012 in. (.20 to .30 mm.) |
| Undersizes available | -.010, -.020, -.030 and -.040 in. (-.254, -.508, -.762, -1.016 mm.) |
| Crankshaft & Main Bearings | |
| Main journal diameter | 2.1265 to 2.127 in. (54.01 to 54.02 mm.) |
| Crankpin journal diameter | 1.8759 to 1.8764 in. (47.648 to 47.661 mm.) |
| Crankshaft end thrust | Taken by thrust washers at centre main bearing |
| Endfloat | .002 to .003 in. (.051 to .076 mm.) |
| Main bearings | Three shell type |
| Bearing material | Steel backed copper-lead |
| Bearing length | 1 1/8 in. (28.5 mm.) |
| Diametrical clearance | .001 to .0027 in. (.0254 to .068 mm.) |
| Undersizes available | -.010, -.020, -.030 and -.040 in. (-.254, -.508, -.762, -1.016 mm.) |
| Cylinder Block | |
| Type | Cylinder cast integral with top half of crankcase |
| Water jackets | Full length |
| Oversize bores : First | .010 in. (.254 mm.) |
| Max. | .040 in. (1.016 mm.) (** .060 and .090 now available) |
| Cylinder Head | |
| Type | Cast iron with vertical valves |
| Port arrangements | Inlet & exhaust ports on same side |
| No. of ports : Exhaust | 2 separate and one siamesed |
| No. or ports : Inlet | 2 siamesed |
| Combustion chamber capacity | 42.5 to 43.5 c.c. (2.59 to 2.65 cu. in.) with valves fitted |
| Gudgeon Pin | |
| Type | Semi-floating. Held by clamp bolt |
| Fit in piston | Free push fit at 20°C (68°F) |
| Outer diameter | .7499 to .7501 in. (19.04 to 19.05 mm.) |
| Lubrication System | |
| Type | Pressure and splash. Wet sump |
| Oil filter | Full flow. Tecalemit felt element. |
| Capacity Oil Filter | 1 pint. (1.2 U.S. pints, .57 litre) |
| Sump capacity | 7 1/2 pints (.42 litre, 9 U.S. pints) |
| Oil cooler capacity | 3/4 pint (.42 litre, .9 U.S. pints) |
| Oil pump - Type | Hobourn-Eaton or eccentric rotor. |
| Pump capacity | 3 1/4 gallons a minute @ 2,000 r.p.m. |
| By-pass valve opens | 12 to 17 lb./sq. in. (4.9 kg./cm2.) |
| Oil pressure relief valve opens | 70 lb./sq. in. (4.9 kg./cm2.) |
| Oil pressure relief valve spring - free length |
3 in. (76.2 mm.) |
| Oil pressure relief valve spring - fitted length |
2 5/32 in. (54.7 mm.) |
| Relief valve spring - load at fitted length |
15.5 to 16.5 lb. (7.0 to 7.5 kg) |
| Normal oil pressure - Idling | Not less than 15 lb./sq. in. (1.05 kg./cm2.) |
| Normal oil pressure - 3,000 r.p.m. | Not less than 50 lb./sq. in. |
| Pistons | |
| Type | Aluminium - Solid skirt |
| No. of rings | 4. 3 compression, 1 oil control |
| Clearance in cylinder : Top | .0036 to .0045 in. (.091 to .121 mm.) |
| Clearance in cylinder : Bottom | .0018 to .0024 in. (.045 to .060 mm.) |
| Width of ring grooves : Top Second Third Oil control |
.064 to .065 in. (1.625 to 1.651 mm.) " " .1578 to .1588 in. (4.008 to 4.033 mm.) |
| Gudgeon pin bore | .7501 to .7503 in. (19.052 to 19.057 mm.) |
| Piston oversizes available | +.010 in., +.020 in., +.030 in., +.040 in. (+.254 mm., +.508 mm., +.762 mm., +1.02mm.) |
| Piston Rings | |
| Top compression ring | Parallel - Cast iron - molybdenum filled |
| 2nd. and 3rd. compression rings | Tapered - Cast iron - molybdenum filled |
| Top ring width | .0615 to .0625 in. (1.562 to 1.587 mm.) |
| 2nd. and 3rd. ring width | .0615 to .0625 in. (1.562 to 1.587 mm.) |
| Top ring fitted gap | .012 to .017 in. (.304 to .431 mm.) |
| 2nd. and 3rd. rings fitted gap | .012 to .017 in. (.304 to .431 mm.) |
| Groove clearance | .0015 to .0035 in. (.038 to .088 mm.) |
| Oil control ring | Slotted scraper |
| Oil control ring - Width | .1552 to .1562 in. (3.94 to 3.96 mm.) |
| Oil control ring fitted gap | .012 to .017 in. (.304 to .431 mm.) |
| Groove clearance | .0016 to .0036 in. (.04 to .09 mm.) |
| Tappets | |
| Type | Barrel with flat base |
| Outside diameter | 13/16 in. (20.64 mm.) |
| Length | 2.293 in. to 2.303 in. (58.25 to 58.5 mm.) |
| Rocker Gear | |
| Length of Rocker Shaft | 14 1/32 in. (356 mm.) |
| Diameter | .624 to .625 in. (15.85 to 15.87 mm.) |
| Rocker arm bore | .7485 to .7495 in. (19.01 to 19.26 mm.) |
| Rocker arm bush - inside diameter | .6255 to .626 in. (15.8 to 15.9 mm.) |
| Ratio | 1.4 to 1 |
| Valves | |
| Head diameter - Inlet | 1.562 to 1.567 in. (38.67 to 38.80 mm.) |
| Head diameter - Exhaust | 1.343 to 1.348 in. (34.11 to 34.23 mm.) |
| Valve seat angle - Inlet & Exhaust | 45 ½° |
| ....... currently incomplete | |
Wodering if you can help, my vin has only 4 numbers 4471, engine number 18ga4h7856 can you help with year was told it is 1964 model.
Cheers
gt? The transmissions are different, but was the flywheel bolt pattern
changed, the clutch size different, what??? The 1967 is supposed to
have a 5 main crank...
http://www.mgexp.com/phorum/list.php?1
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