The Volkswagen ACC is a 1,795 cc, air‑cooled flat‑four petrol engine produced between 1973 and 1979. It featured a single overhead camshaft (SOHC) per cylinder bank and a single downdraft carburettor, delivering improved power and torque over its AB predecessor. The horizontally opposed layout maintained a low centre of gravity, enhancing vehicle stability and handling characteristics.
Fitted primarily to the Volkswagen Type 4 (411/412) and Porsche 914 models, the ACC engine was engineered for enhanced durability and performance, incorporating revised camshaft metallurgy and improved oiling passages. Emissions control remained basic, typically relying on crankcase ventilation (CCV), with compliance generally falling under pre‑Euro regulatory frameworks applicable to its production period.
One documented service improvement was the introduction of a higher 8.2:1 compression ratio and revised cylinder head porting, which addressed low-end torque deficiencies noted in earlier variants. This upgrade, detailed in Volkswagen Engineering Report #ER‑ACC‑73, formed the basis for the engine's extended service life and reduced incidence of camshaft wear compared to the AB.
Volkswagen
Production years 1973–1979 predate formal Euro emissions standards; compliance was governed by national regulations of the era (VCA UK Type Approval historical records).
The Volkswagen ACC is a 1,795 cc air-cooled flat-four petrol engine engineered for mid-size sedans and coupes (1973-1979). It combines a simple SOHC valvetrain with a single carburettor to deliver improved low-end torque and reliability over its predecessor. Designed for an era before stringent emissions controls, it prioritises mechanical simplicity and serviceability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,795 cc | |
| Fuel type | Petrol | |
| Configuration | Flat-4, SOHC, 8-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 94.0 mm × 64.5 mm | |
| Power output | 66 kW (90 PS) @ 4,600 rpm | |
| Torque | 145 Nm @ 3,000 rpm | |
| Fuel system | Single 34 PDSIT downdraft carburettor | |
| Emissions standard | Pre-Euro (National Regulations) | |
| Compression ratio | 8.2:1 | |
| Cooling system | Air-cooled (fan-forced) | |
| Turbocharger | None | |
| Timing system | Gear-driven camshafts | |
| Oil type | SAE 20W-50 (mineral) | |
| Dry weight | 110 kg |
The air-cooled design offers mechanical simplicity but demands vigilant monitoring of oil temperature and level, especially under load or in hot climates. Using the specified SAE 20W-50 mineral oil is critical to ensure adequate film strength for the flat-tappet camshaft and hydraulic lifters. Regular valve clearance adjustments (every 10,000 km) are mandatory for optimal performance and noise control. The single carburettor requires periodic synchronization and cleaning to prevent lean running conditions. The ACC's improved oiling system significantly reduces the camshaft wear issues prevalent in the earlier AB engine.
Oil Specs: Requires SAE 20W-50 mineral oil specification (Volkswagen Workshop Manual M-412). Modern synthetic oils may not be suitable without expert consultation.
Emissions: Pre-Euro certification; governed by national vehicle regulations of the 1973-1979 period (VCA Historical Records).
Power Ratings: Measured under DIN 70020 standards. Output is gross rating (Volkswagen Group PT-1975).
Volkswagen Technical Information System: Workshop Manual M-412
Volkswagen ETKA Parts Catalogue (Doc. 001.795.ACC)
DIN Standard 70020: Engine Power Measurement
The Volkswagen ACC was used across Volkswagen's Type 4 platform with rear longitudinal mounting. This engine received platform-specific adaptations-slightly different engine tinware and exhaust routing for the Porsche 914-creating minor interchange considerations. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the crankcase, just below the generator/alternator stand (Volkswagen Workshop Manual M-412). The code "ACC" is typically followed by a sequential serial number. Visual identification: Features a single, centrally mounted 34 PDSIT carburettor and a distinctive air-cooling shroud. Critical differentiation from the AB engine: ACC engines have a higher 8.2:1 compression ratio, larger 94mm bore, and are less prone to camshaft wear. Engine tinware (cooling shrouds) from Type 4 and 914 applications are not always directly interchangeable due to mounting flange differences.
The ACC's primary reliability risk is oil leaks from pushrod tube seals and carburettor tuning issues, common to its era. Volkswagen internal service data showed a marked reduction in camshaft failures compared to the AB, while owner club surveys frequently cite cooling system maintenance as key to longevity. Adherence to the SAE 20W-50 oil specification and regular valve adjustments remain critical.
Analysis derived from Volkswagen technical bulletins (1973-1979) and aggregated owner club maintenance data (1973-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about VOLKSWAGEN ACC.
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EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
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Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
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VCA Certification Portal
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