The Renault 800 705 is a 797 cc, inline-four petrol engine produced between 1964 and 1973. It features a single overhead camshaft (SOHC), two valves per cylinder, and a single-barrel carburettor, delivering 30 kW (41 PS) of power and 62 Nm of torque. The engine's compact design prioritised simplicity and low-cost maintenance for urban mobility.
Fitted to the Renault 4 and R4 L, the 800 705 was engineered for economical city driving and light utility use. Its high-revving character provided adequate performance for small-car applications, with emissions compliance achieved through basic atmospheric aspiration and minimal exhaust treatment, meeting early European standards for its era.
A documented concern is cylinder head cracking in high-mileage examples, highlighted in Renault Service Bulletin SI 67-008. This issue stems from thermal stress due to inadequate cooling flow in the combustion chamber area and was addressed by revised casting geometry and improved coolant jacket design in production from mid-1969 onwards.
Production years 1964–1972 meet pre-Euro standards; 1973 models may have minor market-specific adjustments depending on local regulations (VCA UK Type Approval #VCA/EMS/5679).
The Renault 800 705 is a 797 cc inline-four naturally aspirated petrol engine engineered for compact city cars (1964-1973). It combines a cast iron block with an aluminium alloy head and a single overhead camshaft to deliver reliable, low-maintenance performance. Designed to meet early European emissions standards, it balances affordability with practical drivability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 797 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, SOHC, 8-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 68.0 mm × 55.0 mm | |
| Power output | 30 kW (41 PS) | |
| Torque | 62 Nm @ 3,500 rpm | |
| Fuel system | Single-barrel carburettor (Solex 26 DIDT) | |
| Emissions standard | Pre-Euro (early French standards) | |
| Compression ratio | 8.5:1 | |
| Cooling system | Water-cooled | |
| Timing system | Chain-driven camshaft | |
| Oil type | SAE 20W-50 mineral oil | |
| Dry weight | 88 kg |
The lightweight, high-revving nature provides responsive acceleration for urban use but requires frequent valve clearance checks every 10,000 km to maintain efficiency. SAE 20W-50 mineral oil is critical due to the lack of modern anti-wear additives in early engine designs. Extended operation at high RPM or under load accelerates cylinder head thermal fatigue, making regular coolant flushes essential. Carburettor jetting must be matched to ambient temperature and altitude to prevent lean-run detonation. Fuel quality should meet EN 228 standards to prevent premature valve seat recession.
Oil Specs: Requires SAE 20W-50 mineral oil (Renault SIB 67-008). Synthetic oils are not recommended for original equipment.
Emissions: Pre-Euro certification applies to all models (VCA Type Approval #VCA/EMS/5679). No later revisions were made.
Power Ratings: Measured under ISO 14396 standards. Output figures apply only to European-market vehicles with standard carburettor settings (Renault TIS Doc. A24682).
Renault Technical Information System (TIS): Docs A24682, SIB 67-008
VCA Type Approval Database (VCA/EMS/5679)
ISO 14396:1994 Internal combustion engines — Determination of engine power
The Renault 800 705 was used across Renault's R4 platform with transverse mounting and no licensed external use. This engine received platform-specific adaptations—revised intake routing for the R4 L variant—and from 1969 the facelifted R4 adopted revised cylinder head casting and coolant jacket geometry to address early cracking issues, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the right side of the block below the cylinder head (Renault TIS A24682). The 7th VIN digit is '8' for 800 series engines. Pre-1969 units feature a flat-top cylinder head with shallow coolant passages and a single-point distributor; post-1969 units have a revised head with reinforced ribs around the combustion chamber and a deeper coolant jacket. Critical differentiation from 800 706: The 800 705 has a 68mm bore and 55mm stroke, while the 800 706 has a 70mm bore. Service parts require production date verification - cylinder heads for pre-1969 engines are incompatible with later blocks due to coolant passage redesign (Renault SIB 67-008).
The 800 705's primary reliability risk is cylinder head cracking on pre-1969 builds, with elevated incidence in sustained high-RPM operation. Internal Renault service reports from 1970 indicated nearly 15% of engines over 80,000 km required head replacement. While UK DVSA MOT data shows minimal emissions-related failures, this is attributed to the absence of complex after-treatment systems. Extended oil change intervals and poor-quality mineral oil accelerate bearing degradation, making adherence to 10,000 km servicing critical.
Analysis derived from Renault technical bulletins (1964-1973) and UK DVSA failure statistics (1973-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about RENAULT 800-705.
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DVLA: Engine Changes & MoT
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Regulation (EC) No 715/2007
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Commission Regulation (EU) 2017/1151
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