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General Data

Directly from the M.G. Midget (Series "TD"), Issue 3 (Export) 78690 -- 1/53 Workshop Manual. These pages contain specifications and measurements for the MGTD.

Note: These pages were scanned with OCR technology and may contain errors. Consult the original manual for accuracy.


GENERAL DATA
               
ENGINE TYPE           XPAG/TD up to Engine No 9407.
            XPAG/TD/2 from Engine No. 9408.
Number of cylinders ... ... ... ... Four
Capacity ... ... ... ... ... ... 1250 c.c. (761 cu. in.).
B.H.P. ... ... ... ... ... ... 54.4 at 5,200 r.p.m.
Bore ... ... ... ... ... ... 66.5 mm. (2.618 in.).
Stroke ... ... ... ... ... ... 90 mm. (3.543 in.).
R.A.C. rating ... ... ... ... ... 10.97 h.p.
Compression ratio ... ... ... ... 7.25 to 1.
System of cooling ... ... ... ... ... Thermo-siphon-pump and fan assisted.
Radiator hose top ... ... ... ... ... Length 4in. (10.16cm.).
            Diameter 2 3/16 in. (5.56 cm.).
Radiator hose bottom ... ... ... ... Length 2¼ in. (5.71 cm.).
          Diameter 1 1/8 in. (2.86 cm.).
First oversize bore ... ... ... ... + .020 in. (.50 mm.).
          Actual bore 2.6381 in. (67 mm.).
Second oversize bore ... ... ...   +.040 in. (1.00 mm.).
          Actual bore 2.6581 in. (67.5 mm.).
Firing order ... ... ... ... ... 1-3-4-2.
Piston clearance at pressure face below oil ring .0021 in. to .0029 in. (.056 mm. to .071 mm.).
Ring gap ... ... ... ... ... ... .006 in. to .010 in. (.152 mm. to .254 mm.).
Number of compression rings ... ... ... Two.
Width of compression rings ... ... ... 2.25 mm. (.0885 in.).
Number of oil rings ... ... ... ... One.
Width of oil ring ... ... ... ... 4.0 mm. (.1575 in.).
Oil pressure relief valve operates ... ... 50 to 70 lb. per sq. in. (3.5 to 5.0 kg./cm.²).
Oil pressure (normal) ... ... ... ... 40 to 45 lb. per sq. in. (2.8 to 3.2 kg./cm.²).
Gudgeon pin type ... ... ... ... Clamped.
          .7087 in. {+.0004 in.
            {+.0006 in.
Gudgeon pin diameter ... ... ... ... 18 mm. {+.015 mm.
            {+.010 mm.
Fit in piston ... ... ... ... ... Double thumb press.
Fit in connecting rod ... ... ... ... Clamped.
Crankpin diameter (standard) ... ... ... 1.772 in. (45 mm.).
Crankpin minimum diameter for regrind ... 1.722 in. (43.75 mm.).
Connecting rod-length between centres ... 7.008 in. (178 mm.).
Connecting rod-type of bearing ... ... Shimless, steel-backed, white-metal-lined.
Connecting rod-side clearance ... ... .004 in. to .006 in. (.10 mm. to .15 mm.).
Connecting rod-diametrical clearance ... .0005 in. to .002 in. (.011 mm. to .056 mm.).
Number of crankshaft bearings ... ... ... Three.
Type of main bearings ... ... ... ... Shimless, steel-backed, white-metal-lined.
Standard main journal diameter ... ... 2.047 in. (52 mm.).
Main journals first regrind diameter ... ... 2.027 in. (51.49 mm.).
Main journals second regrind diameter (minimum) 2.007 in. (50.98 mm.).
Main bearings-length ... ... ... ... Front 1.496 in. (38 mm.).
          Centre 1.496 in. (38mm.).
          Rear 1.575 in. (40 mm.).
Centre main bearing-end clearance ... ... .0014 in. to .0037 in. (.035 mm. to .095 mm.).
Main bearings-diametrical clearance ... ... .0008 in. to .003 in. (.020 mm. to .075 mm.).
Crankshaft-end thrust taken on ... ... Centre bearing.
Number of camshaft bearings ... ... ... Three
Type of camshaft bearings ... ... ... White metal (front).
        Zinc alloy (rear and centre).


GENERAL DATA - continued
               
Camshaft-bearing clearance ... ... ... Front .0016 in. to .004 in. (.04 mm. to .10 mm.).
        Rear and centre .0018 in. to .0037 in. (.045 mm. to .095 mm.).
Camshaft-end thrust taken on ... ... ... Front end.
Camshaft-end float ... ... ... ... ... .005 in. to .013 in. (.125 mm. to .325 mm.).
Camshaft-drive (type) ... ... ... ... ... Duplex chain, 3/8 in. pitch, 60 pitches, endless.
Valve timing markings ... ... ... ... ... White chain links and " T " marks on wheels.
Exhaust valve throat diameter ... ... ... 1.024 in. (26 mm.).
Exhaust valve diameter ... ... ... ... ... Head 1.221 in. (31 mm.) Stem .315 in. (8 mm.).
Inlet valve throat diameter ... ... ... ... 1.181 in. (30mm.).
Inlet valve diameter ... ... ... ... ... Head 1.299 in. (33 mm.) Stem .315 in. (8 mm.).
Valve seat angle ... ... ... ... ... ... 30º
Tappet type ... ... ... ... ... ... Hollow.
Valve lift-Inlet ... ... ... ... ... ... .315 in. (8 mm.).
Valve lift-exhaust ... ... ... ... ... ... .315 in. (8 mm.).
Inlet valve opens ... ... ... ... ... ... 11º before T.D.C.} From {5º before T.D.C.
Inlet valve closes ... ... ... ... ... ... 57º after B.D.C. } Engine {45º after B.D.C.
Exhaust valve opens ... ... ... ... ... 52º before B.D.C. } XPAG/TD/2 {45º before B.D.C.
Exhaust valve closes ... ... ... ... ... 24º after T.D.C.} No. 24116 {5º after T.D.C.
Valve spring pressure-shut ... Inner 31 lb. at 1.753 in. (14.06 kg. at 4.453 cm.).} Total 93 lb.
    Outer 62 lb. at 1.847 in. (28.12 kg. at 4.692 cm.).} (42.18 kg.)
Valve spring pressure-open ... Inner 43 lb. at 1.438 in. (I 9.5 kg. at 3.678 cm.).} Total 123 lb.
    Outer 80 lb. at 1.532 in. (36.29 kg. at 3.89 cm.).} (55.79 kg.)
      Engines up to No. XPAG/TD2/24115:
Inlet and exhaust valve working clearance (hot) .019 in. (.48 mm.).
  Engines from-No. XPAG/TD2/24116:
Inlet and exhaust valve working clearance (hot) .012 in. (.30 mm.).
Valve guides ... ... ... ... ... ... Removable.
               
FUEL SYSTEM              
Petrol tank reserve level ... ... ... ... Warning light on panel.
Fuel delivery ... ... ... ... ... ... S.U. electric pump.
Carburetters ... ... ... ... ... ... S.U. semi-downdraught.
Carburetter needles ... ... ... ... ... Standard-ES. Weak-AP. Rich-EM.
             
CLUTCH            
Type (up to Engine No. 9407) ... ... ... Borg & Beck 7¼ in. (18.4 cm.) diameter. Dry plate.
Type (from Engine No. 9408) ... ... ... Borg & Beck 8 in. (20.3 cm.) diameter. Dry plate.
Facing ... ... ... ... ... ... Type RYZ on 7" diameter clutch.
        Moulded type on 8" diameter clutch.
         
GEARBOX        
Synchromesh ... ... ... ... ... ... Second, third and top.
        Gearbox Overall 8/41 Overall 8/39 Overall 9/41
Ratios ... Top 1.00 5.125 4.875 4.555
    Third 1.385 7.098 6.752 6.309
    Second 2.07 10.609 10.09 9.429
    Bottom 3.5 17.938 17.06 15.942
    Reverse 3.5 17.938 17.06 15.942


GENERAL DATA - continued
               
FRONT SUSPENSION AND STEERING    
Camber (static position) ... ... ... ... Nil (tolerance ± 1º).
Castor angle ... ... ... ... ... ... 2º ± ½º with side-members parallel to road.
Toe-in ... ... ... ... ... ... Nil.
King-pin inclination ... ... ... ... ... 9º to 10½º full bump.
Track ... ... ... ... ... ... Front 47 3/8in. (1.203 m.). Rear 50 in. (1.27 m.).
Turning circle ... ... ... ... ... ... 31 ft. 3 in. (9.525 m.).
Wheelbase ... ... ... ... ... ... 7 ft. 10 in. (2.388 m.).
Tyre size ... ... ... ... ... ... 5.50-15.
Tyre pressures ... ... ... ... ... ... 18 lb. per sq. in. (1.27 kg./cm.²).
               
REAR AXLE              
Type of axle ... ... ... ... ... ... Semi-floating.
Type of drive ... ... ... ... ... ... Hypoid.
Ratio ... ... ... ... ... ... 8/41, 8/39 or 9/41.
Adjustment ... ... ... ... ... ... By spacers and special fixtures.
               
BRAKES              
Type ... ... ... ... ... ... Lockheed hydraulic two leading shoe (front) (9 in. dia.).
Type of linings ... ... ... ... ... ... Ferodo MR.19.
Lining size--front ... ... ... ... ... ... 8.75 in. x 1.5 in. x .187 in. (22.22 cm .x 3.81 cm. x
.47 cm.).
Lining size--rear ... ... ... ... ... ... 8.75 in. x 1.5 in. x .187 in. (22.22 cm .x 3.81 cm. x
.47 cm.).
Number of rivets ... ... ... ... ... ... Twelve per lining.
               
SPRINGS (front)              
Type ... ... ... ... ... ... Coil.
Free length ... ... ... ... ... ... 9.59 in. ± 1/16 in. (24.36 cm. ± 1.58 mm.).
Mean coil diameter ... ... ... ... ... 3.238 in. (8.24 cm.).
Number of effective coils ... ... ... ... 7½.
Diameter of wire (ground) ... ... ... ... .498 in. (1.27 cm.).
Maximum deflection ... ... ... ... ... 4.24 in. (10.78 cm.).
               
SPRINGS (rear)              
Type ... ... ... ... ... ... Half-elliptic.
Length ... ... ... ... ... ... 42 in. (106.7 cm).
Width ... ... ... ... ... ... 1½ in. (3.81 cm.).
Number of leaves ... ... ... ... ... ... Seven.
Thickness of leaves ... ... ... ... ... 7/32 in. (5.56 mm.).
Camber (free) ... ... ... ... ... ... 4.1 in. (10.4 cm.).
Working load ... ... ... ... ... ... 500 lb. at ½ positive camber.
              (226.8 kg. at.12.7 mm. positive camber.)
HYDRAULIC DAMPERS          
Type ... ... ... ... ... ... Girling or Armstrong.
               
ELECTRICAL              
Distributor rotation ... ... ... ... ... ... Counter-clockwise.
Automatic advance ... ... ... ... ... 32º on crankshaft.
Contact breaker gap (first type) ... ... ... .010 in. to .012 in. (.25 mm. to .30 mm.).
Contact breaker gap (second type) ... ... .014 in. to .016 in. (.36 mm. to .41 mm.).
Sparking plug (engines prior to No.  
XPAG/TD2/22735) ... ... ... ... ... ... Champion L.10S (standard equipment) (14 mm.).
        K.L.G. E.80.
        Lodge HN or HNP.


GENERAL DATA - continued
               
Sparking plug (engines from No.        
XPAG/TD2/22735) ... ... ... ... ... Champion NA.8.
Sparking plug gap. ... ... ... ... ... .020 in. to .022 in. (.50 mm. to .56 mm.).
Ignition timing ... ... ... ... ... T.D.C. (full retard).
Charging system ... ... ... ... ... C.V.C.
Battery ... ... ... ... ... ... Lucas GTW9A, 51-amp. at 10 hours. 12-volt.
              Positive earth return.
               
CAPACITIES              
Sump ... ... ... ... ... ... 9 pints (5.1 litres) ; from Engine No. 14948.
              10½ pints (5.96 litres).
Gearbox ... ... ... ... ... ... 1¼ pints (.71 litre).
Rear axle ... ... ... ... ... ... 2¼ pints (1.3 litres).
Cooling system ... ... ... ... ... ... 12 pints (6.8 litres).
Brake fluid ... ... ... ... ... ... 1 pint (.57 litre).
Fuel tank ... ... ... ... ... ... 12½ gallons (57 litres).
               
GENERAL DIMENSIONS          
Length ... ... ... ... ... ... 145 in. (3.683 m.).
Width ... ... ... ... ... ... 58 5/8 in. (I .489 m.).
Height ... ... ... ... ... ... 53 in. (1.346 m.).
Ground clearance ... ... ... ... ... ... 6 in. (15.24 cm.).
Weight (unladen) ... ... ... ... ... ... 18½ cwt. (2,072 lb.) (941 kg.).
Weight (laden and with two passengers) ... 22 cwt. (2,464 lb.) (1120 kg.).
     
TORQUE SPANNER DATA
Cylinder head stud nuts ... ... ... ... 600 lb. ins. (6.9 m./kg.).
Connecting rod big-end bolts ... ... ... ... 320 lb. ins. (3.7 m./kg.).
(to next split pin hole)          
Main bearing cap nuts ... ... ... ... 75 lb. ins. (8.6 m./kg.).
(to next split pin hole)          
Steering wheel attachment nut ... ... ... ... 500 lb. ins. (5.75 m./kg.).
Gudgeon pin clamp screw ... ... ... ... 400 lb. ins. (4.6 m./kg.).*

*Warning: Under torque data, there is an error that was in the original shop manuals . The torque listed for the gudgeon pin clamp bolt is 400 in lbs (33.3 ft lbs). The torque should only be no more that 27 ft lbs and preferably 25 ft lbs. The gudgeon pin clamp bolt is the same size as the big end bolts (8 X 1mm) and the torque given for the big end bolt is 320 in lbs (26.7 ft lbs).


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