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Reliant Production Engines

Whilst Reliant started with JAP engines (1935 - 1938), closely followed by the Austin 7 engine (1938 - 1939), 1939 saw the introduction of the first Reliant made engine, a 747cc side-valve unit that was based on the Austin 7 engine.  This was then followed in 1962 by the Reliant 600cc OHV engine that was based on a Chinese copy of a Standard engine. This was updated several times into a 848cc engine.  Reliant Sports Cars have also used various Ford, Rover and Nissan engines though this pages concentrates on the specifications of Reliant’s own engine used in its economy range.

Reliant 750cc side-valve engine

747cc side-valve

Reliant 600cc OHV engine

600cc OHV

Reliant 850cc OHV engine

847cc OHV

747cc Side Valve

1939 - 1962

Based on the Austin 7 engine with subtle differences to force people to go to Reliant for spares and not Austin dealerships, the first all Reliant engine is said to have fired up on 3rd September 1939 as news of World War II broke on the radio. With a 747cc capacity the engine was a cast iron  4-cylinder, water-cooled side-valve engine. Fitted to few vehicles in 1939  just before all manufacturers were forced to stop building vehicles, the engine was again put in use from 1946 when production started again.  In 1950 it received a number of updates and continued to be used with minor alterations until 1960. In addition to all girder fork vehicles from 1939, the engine was also used in the Reliant Regal passenger cars from 1953 to 1960.

 

Technical Details: (Example from 1950 Reliant Regent)

 

Four-cylinder side-valve. Bore, 56 m.m. Stroke, 76 m.m. Capacity, 747.5 c.c. R.A.C. rating, 7.5 h.p. Maximum B.H.P., 14 at 3,500 r.p.m. Compression ratio, 5.7 : 1. Detachable cast iron cylinder head. Cast iron cylinder block mounted on aluminium crankcase. Crankshaft of manganese-molybdenum steel mounted on three steel-backed main bearings. Connecting rods of nickel alloy steel; camshaft of case-hardened steel. Engine mounted on rubbers at three points.  Lubrication - Submerged gear-type oil pump delivers oil under pressure to the crankshaft main bearings, and thence to the camshaft bearings. The connecting rod bearings are supplied from the main bearings through oilways drilled in the crankshaft webs. Gudgeon pins and cylinder walls are splash lubricated. Capacity of sump, five pints. Dipstick fitted. Cooling System - Thermo-syphon and two-bladed fan driven by belt from engine pulley.  Fuel System - “Solex” carburettor incorporating easy starting device, supplied by “A.C.” petrol punp driven direct from camshaft. Petrol tank capacity, 3.5 gallons. Ignition - By 12 voly battery and coil distributor mounted on cylinder-head, incorporating automatic advance and retard mechanism with extension drive from camshaft. Sparking plugs, 14 m.m.  Firing order 1, 3, 4, 2. Ignition occurs 1/8 in. before T.D.C. Clutch - Borg and Beck dry single plate type, with self-lubricating withdrawal bearing.

600cc OHV

1962 - 1968

Based on a Chinese version of the cast-iron Standard engine, Reliant started work on an overhead-valve (OHV) engine in 1959. Whilst the initial prototypes were heavier than the side-valve unit it was replacing, Reliant planned for the new engine to be much lighter and so developed an all aluminium engine.  This weighed in 20lb lighter than the side-valve unit and meant that the cylinder capacity could be reduced to 600cc and yet still provide more power. The engine was fitted to the new Regal 3/25 in 1962 and laid claim to being Britain’s first mass produced all-aluminium engine.

 

Technical Details: (Example from 1962 Regal 3/25)

 

Reliant 600 c.c. four cylinder high efficiency overhead valve, water cooled. Maximum B.H.P 24.2 at 5,259 r.p.m. Compression ratio 7.8:1. Bore 2.2 in. Stroke 2.4 in. Detachable die cast aluminium cylinder head with cast iron valve guides and scintered iron seats, Die cast aluminium cylinder block and crank case with removable wet liners. Forged steel super finished crankshaft mounted on three steel-backed main bearings. Engine mounted on rubbers at three points. Lubrication - Submerged gear type oil pump delivers oil under pressure to the crankshaft main bearings, thence to the camshaft bearings. The connecting rod bearings are supplied from the main bearings through oilways drilled in the crankshaft webs. Gudgeon pins and cylinder walls are splash lubricated. Capacity of sump, seven pints. Dipstick fitted.  Cooling System - Pump assisted circulation and two bladed fan driven by belt from engine pulley. Fuel System - “Solex” downdraught carburettor, incoporating easy starting device and fitted with air cleaner supplied by “A.C.” petrol pump driven direct from camshaft. Petrol tanl capacity, 6 gallons. Ignition - by 12 volt battery and coil, distributor mounted on cylinder head incorporating vacuum-opereated advance and retard mechanism with extension driven from camshaft. Sparking plugs 14mm.  long reach.  Firing order 1,3,4,2. Ignition occurs 10 degrees before T.D.C. in fully retard position.  Clutch - Borg and Beck dry single plate type, with self-lubricating withdrawal bearing.

700cc OHV

1968 - 1973

The 600c engine was used in both the Regal 3/25 and the four-wheeled Rebel though in the latter customers were complaining of the lack of power. To help boost perfomance for the Rebel, the engine capacity was increased to 701cc which along with a new Zenith downdraught carburettor, increased BHP to 31.5 for the Rebel whilst a 29.5 NHP version was used in the Regal. (Now callled the Regal 3/30)

 

Technical Details: (Example from 1967 Regal 3/30)

 

Reliant four cylinder high efficiency overhead valve, water cooled. Bore 2.38 in. Stroke 2.4 in. Capacity 700 c.c. Maximum B.H.P 29.5 at 5,000 r.p.m. Maximum torque 34.5 lbs. ft. at 2,500 r.p.m. Compression ratio 7.5:1. Detachable die cast aluminium cylinder head with cast iron valve guides and scintered iron seats, Die cast aluminium cylinder block and crank case with removable wet liners. Forged steel super finished crankshaft mounted on three steel-backed main bearings. Engine mounted on rubbers at three points. Lubrication - Submerged eccentric rotor type oil pump, full vlow oil filter. Capacity of sump, five pints. Cooling System - Pump assisted circulation and four bladed fan driven by V-belt from engine pulley. Fuel System - “Zenith” downdraught carburettor, “A.C.” petrol pump. Paper element air cleaner. Petrol tank capacity, 6 gallons. Ignition - by 12 volt battery and coil. Clutch - Borg and Beck dry single plate type.

750cc OHV

1972 - 1975

The Reliant engine received further modifications in October 1972 when the capacity was updated again to 748cc for the Rebel and then for new Robin range that was soon to follow.

 

Technical Details: (Example from 1974 Robin)

 

Reliant four cylinder high efficiency overhead valve, water cooled. Bore (2.46”) 62.5 mm. Stroke(2.4”) 60-96 mm. Capacity 748cc.  BHP (DIN) 32 at 5500 rpm. Torque (DIN) 36.5 at 3000 rpm.  Compression ratio 7.5:1. Speed at 1000 rpm in Top 15.5 mph. Detachable die cast aluminium cylinder head with cast iron valve guides and scintered iron seats, Die cast aluminium cylinder block and crank case with removable wet liners. Forged steel super finished crankshaft mounted on three steel-backed main bearings. Engine mounted on rubbers at three points. Emissions controlled to regulations. Lubrication - Submerged eccentric rotor type oil pump, full flow filter. Capacity 5.5 pints including filter (3.13 litres). Cooling System - Pump assisted circulation and fan driven by v-belt from engine pulley. Anti-freeze standard. Fuel System - Downdraught carburettor, petrol pump.  Paper element air-cleaner. Petrol tank capacity, 6 gallons (27.3 lites). Ignition - 12 volt battery and coil, suppression controlled and regulation. Clutch 6 1/4” 155.8 mm diameter single dry plate - cable operated.

850cc OHV

1975 - 2002

In 1975 the engine received its last major change when it was increased to 848cc and was now complemented with a SU type carburattor which produced 40 BHP. This gave the Robin a fairly respectable 0-60mph time of 16 seconds. The engine remained in production for over 25 years until Reliant finally closed its doors.  The engine did become a HT-E version in 1984 that was fitted to the Rialto 2 range.  This had increased torque in an attempt to improve economy though following issues, especially with the introduction of a new fuel in 1985, the HT-E engine was dropped reverting back to the standard unit in 1985.  Other attempts to improve power were made with both a BRM version and a fuel injected version though neither of these models made it into production.

 

Technical Details: (Example from 1998 Robin)

 

Four cylinder in line OHV water cooled Aluminium alloy cylinder head and block with removable wet cylinder liners. Bore x Stroke: 62.5 x 69.09mm (2.46 x 2.72ins.). Capacity: 848cc (51.74 cu.in). Max Power: 29.8/40 DIN kW/PS at 5500rpm. Max Torque: 62.4/46 DIN Nm/Lb.ft at 3,500rpm. Compression Ratio: 9.5:1. Cooling System: Pump assistant circulation. Cooling fan and pump driven by V-belt from engine pulley. Cooling System Capacity: 2.84 litres (5pts). Ignition System: 12V IEC 130/40 battery (negative earth). Alternator, Pre-engaged starter motor. Ballasted coil. Camshaft driven distributor with sliding contact breaker points.

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