Morris Minor Owners Club
Potteries Branch
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Morris Minor Owners ClubPotteries Branch |
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Engine Information
There were four types of engine fitted to the Morris Minor. Each one corresponds to the series of car.
| Series | Engine | Capacity | Compression | BHP | Torque | Bore | Stroke | 0-50 MPH | Top speed |
| Series MM | Sidevalve | 918cc | 6.6:1 | 27.5 @ 4400 RPM | 39 lb/ft @ 2400 RPM | 57mm | 90mm | 37.1 Sec | 62 MPH |
| Series II | A-series | 803cc | 7.2:1 | 30 @ 4800 RPM | 40 lb/ft @ 2400 RPM | 58mm | 76mm | 29.2 Sec | 62 MPH |
| Series 3 | A-series | 948cc | 8.3:1 | 37 @ 4750 RPM | 50 lb/ft @ 2500 RPM | 62.9mm | 76.2mm | 18.5 Sec | 75 MPH |
| Series 5 | A-series | 1098cc | 8.5:1 | 48 @ 5100 RPM | 60 lb/ft @ 2500 RPM | 64.6mm | 83.7mm | 15.8 Sec | 78 MPH |
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Note:- Two designs of side valve engine were fitted to the Series MM: |
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Type USHM 2. Up to engine no. 77000 No oil filter on early engines. No thermostat No water pump – thermo syphon cooling Dynamo attached to cylinder head |
Type USHM 3. Engine no 77001 on Oil Filter. Thermostat in alloy housing Blanking plate for optional water pump and heater Alloy water jacket with dynamo attached Engine drain tap when water pump fitted Re designed cylinder head Thermo syphon or water pump cooling |
Gearbox / Rear Axle Information
ALL gearboxes fitted to the Morris Minor had synchromesh on 2nd, 3rd and top gears but not on bottom or reverse.
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Series |
Engine |
Gearbox Type |
Bottom |
2nd |
3rd |
Top |
Reverse |
Diff ratio |
Clutch |
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Series MM |
Sidevalve 918cc |
Cast Iron |
3.95 |
2.31 |
1.54 |
1 |
3.95 |
4.55 (9/41) or optional 5.286 (7/37) or 5.375 (8/43) |
6 1/4" Spring |
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Series II |
A-series 803cc |
Aluminium alloy. Smooth casing with no remote housing |
4.09 |
2.588 |
1.679 |
1 |
5.174 |
5.286 (7/37) |
6 1/4" Spring |
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Series 3 |
A-series 948cc |
Aluminium alloy. Smooth casing with remote housing |
3.628 |
2.374 |
1.412 |
1 |
4.664 |
4.55 (9/41) |
6 1/4" Spring |
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Series 5 |
A-series 1098cc |
Aluminium alloy. Ribbed casing with remote housing |
3.628 |
2.172 |
1.412 |
1 |
4.664 |
4.22 (9/38) |
7 1/4" Spring |
| Midget |
A-series
1275cc |
Aluminium alloy. Ribbed casing with remote housing | 3.2 | 1.916 | 1.357 | 1 | 4.114 | 3.9 (10/39) |
6 1/2"
Diaphragm |
NOTE: The Midget gearbox information is included here for completeness but it was never factory fitted to a Morris Minor