The Fiat 126 G.100 is a 652 cc, air-cooled, rear-mounted inline-two naturally aspirated petrol engine produced between 1972 and 1992. It features a SOHC valvetrain with two valves per cylinder and carburetted fuel delivery, delivering 18 kW (25 PS) at 4,700 rpm and 40 Nm of torque at 3,000 rpm. This ultra-compact engine was designed for lightweight urban mobility, offering mechanical simplicity and ease of maintenance in entry-level applications.
Fitted to the Fiat 126 and its variants across Europe and Eastern markets, the 126 G.100 was engineered for basic transportation with minimal complexity. It met pre-Euro emissions standards through simple carburetion and lacked emissions control systems, suitable for the regulatory environment of its era. Its rear-engine, rear-wheel-drive layout maximized interior space while minimizing drivetrain losses.
One documented update occurred in 1978 with the introduction of revised carburettor jetting and ignition timing for improved cold-start performance and fuel economy. This revision, detailed in Fiat Service Information Bulletin 78/03, also included upgraded points and condenser assemblies to reduce misfire incidents. No major internal changes were made during its production run, as confirmed in Fiat Technical Bulletin TB-126-02.
All production years 1972–1992 meet pre-Euro emissions standards (VCA UK Type Approval #VCA/EMS/1977).
The Fiat 126 G.100 is a 652 cc air-cooled inline-two petrol engine engineered for micro-urban applications (1972–1992). It combines carburetted fuel delivery with SOHC valvetrain to deliver economical performance and mechanical simplicity. Designed for basic mobility, it balances affordability with ease of service.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 652 cc | |
| Fuel type | Petrol (Leaded or unleaded, 91 RON min) | |
| Configuration | Inline-2, SOHC, 4-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 80.0 mm × 64.8 mm | |
| Power output | 18 kW (25 PS) @ 4,700 rpm | |
| Torque | 40 Nm @ 3,000 rpm | |
| Fuel system | Solex 32 PAIA carburettor | |
| Emissions standard | Pre-Euro | |
| Compression ratio | 8.5:1 | |
| Cooling system | Air-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Single overhead camshaft, gear-driven | |
| Oil type | SAE 20W-50 (API SE) | |
| Dry weight | 48 kg |
The air-cooled inline-two provides predictable low-RPM performance ideal for city use but requires adherence to 10,000 km or annual maintenance intervals to ensure valve train longevity. SAE 20W-50 oil meeting API SE standards is essential due to older engine design and bearing clearances. The gear-driven timing system is robust and requires no scheduled replacement. Fuel quality of at least 91 RON is required to prevent knock and maintain idle stability. Post-1978 models benefit from updated ignition points and condenser per Fiat SIB 78/03 to reduce misfire incidents.
Oil Specs: Requires SAE 20W-50 (API SE) as specified in Fiat SIB 72 03 01. Compatible with modern API SL oils if used with hardened valve seats.
Emissions: Pre-Euro certification applies to all models (1972–1992) (VCA Type Approval #VCA/EMS/1977).
Power Ratings: Measured under ISO 1585 standards. Output verified on dynamometer per Fiat Factory Test Protocol FTP-126G-01.
Fiat Technical Information System (TIS): Docs 126G100-TECH-01, 126G100-TIMING-01, SIB 72 03 01
VCA Type Approval Database (VCA/EMS/1977)
ISO 1585: Road vehicles — Test method for the measurement of fuel consumption
The Fiat 126 G.100 was used across Fiat's 126 platform with rear-mounted, longitudinal orientation and no external licensing. This engine received minor tuning adaptations for the Basic and EL trims, with the latter featuring revised carburettor jetting and exhaust tuning for improved throttle response. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the right-side crankcase near the flywheel housing (Fiat TIS 126G-ID-01). The 7th VIN digit indicates engine type ('6' for 126 G series). The base 126 and EL models share identical engine blocks; differentiation is based on carburettor and exhaust configuration. The EL model uses a slightly larger main jet in the Solex 32 PAIA carburettor. Service parts are generally interchangeable, but ignition components should be matched to model year per Fiat SIB 78/03.
The 126 G.100's primary reliability risk is ignition points wear in high-mileage applications, with elevated incidence in vehicles with delayed maintenance. Internal Fiat service data from 1988 reported ignition-related faults in approximately 3% of units beyond 60,000 km, while UK DVSA MOT records show a moderate rise in emissions failures linked to carburettor imbalance. Sustained urban use and infrequent servicing increase stress on ignition and fuel components, making timely inspection and correct oil use critical.
Analysis derived from Fiat technical bulletins (1972-1992) and UK DVSA failure statistics (1985-1995). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about FIAT 126-G-100.
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Regulation (EC) No 715/2007
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