BMC Bulletin - Introduction of Sprite MKIIa

Attached is an original service bulletin from BMC Australia. The text of the bulletin is as follows:


INTRODUCTION AUSTIN HEALEY IIa AND MORRIS 6 CWT VAN.


A further development of the ever popular 'A' series power unit is now of greater capacity (1098 c.c.) and developing more power and torque than the 948 c.c. engine which it replaces.


The following specifications are the main differences between the 948 c.c. and 1098 c.c. units.

SPRITE IIa

MORRIS 6 CWT.

ENGINE

10 CG

10 AM

Bore

2.543 in

2.543 in

Stroke

3.296 in

3.296 in

Capacity

1098 c.c.

1098 c.c.

Comp. Ratio

8.9:1

8.5 or 7.5:1

B.H.P.

56 at 5750 r.p.m.

H.C. 48 at 5100 r.p.m.

L.C. 45 at 5100 r.p.m.

Torque

61 lbs./ft. at 2750 rpm

H.C. 60 lbs./ft. at 2500 rpm

L.C. 57 lbs./ft. at 3000 rpm

CRANKSHAFT

Main Bearing Length

1.0625 in

1.0625 in

Main Bearing Material

Steel backed lead bronze with lead indium faced surface

Steel backed lead bronze with lead indium faced surface

Big End Bearing Side Clearance

.008/0.12 in

.008/0.12 in

Big End Bearing Diametrical Clearance

.001/.0025 in

.001/.0025 in

SPRITE IIa

MORRIS 6 CWT

​PISTONS

Type

Solid Skirt

Solid Skirt

Clearance Bottom Skirt

.0005/.0011 in.

.0005/.0011 in.

Clearance Top Skirt

.0021/.0037 in.

.0021/.0037 in.

GUDGEON PIN

Type

Fit

Fully Floating

Hand Push

Fully Floating

Hand Push

PISTON RINGS

Compression Top

Internally chamfered chrome faced.

Internally chamfered chrome faced.

VALVES

Head Dia. Inlet

1.156 in

1.156 in

VALVE TIMING

Inlet Valve Opens

Inlet Valve Closes

Exhaust Opens

Exhause Closes

​5⁰ B.T.D.C.

45⁰ A.B.D.C.

51⁰ B.B.D.C.

21⁰ A.T.D.C.

with .021 in. valve

rocker clearance for

checking purposes

only.

VALVE SPRINGS

Free Length Inner

1.672 in

-

Free Length Outer

1.750 in

1.750 in

Fitted Length Inner

1.179 in

-

Fitted Length Outer

1.291 in

1.291 in

Working Coils Inner

6.5

-

Working Coils Outer

4.5

4.5

Pressure Valve Open Inner

30 lbs.

-

Pressure Valve Open Outer

88 lbs.

88 lbs.

Pressure Valve Closed Inner

18 lbs.

-

Pressure Valve Closed Outer

52 lbs.

52 lbs.

CAMSHAFT

Bearing Type

3 white metal lined steel backed

3 white metal lined steel backed

FUEL

Type

Twin HS2

Single HS2

NEEDLES

Standard

GY

AN

Rich

M

H.6

Weak

GG

EB

Spring

Blue

Red

SPRITE IIa

MORRIS 6 CWT

IGNITION

Distributor

40919 A Lucas

HC 40849 Lucas

LC 40899 Lucas

TIMING

5⁰ B.T.D.C.

3⁰ B.T.D.C.

CLUTCH

Diameter

7.25 in.

7.25 in.

Pressure Spring

Red

Yellow

GEARBOX

Type

Baulk Ring

Baulk Ring

Ratio Top

1.0:1

1.0:1

Third

1.357:1

1.41:1

Second

1.916:1

2.172:1

First

3.2:1

3.628:1

Reverse

4.114:1

4.664:1

REAR AXLE

Ratio

4.22:1

4.22:1

BRAKES

Rear

Disc 8.25 in.

Drum 8 x 1.5 in.

Front

Drum 7 x 1.25 in.

Drum 7 x 1.25 in.

N. PRESCOTT.

SERVICE MANAGER


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