The Fiat 100 GL.040 is a 1,297 cc, inline-four naturally aspirated petrol engine produced between 1972 and 1985. It features a single overhead camshaft (SOHC), two valves per cylinder, and a cast-iron block with aluminium head, delivering reliable performance for compact city driving. In standard form it produced 41 kW (56 PS) at 5,600 rpm and 92 Nm of torque, powering the Fiat 127 and derivatives with mechanical simplicity and ease of maintenance.
Fitted to the Fiat 127, 127 Panorama, and SEAT 127 models, the 100 GL.040 was engineered for economical urban transportation and high-volume production. Its front-engine, front-wheel-drive layout optimized interior space, while wet-sump lubrication and carburetted fuel delivery ensured low-cost servicing. Emissions compliance was managed through basic crankcase ventilation and lean mixture tuning, meeting early Italian national standards (Direttiva Ministeriale 72/377/CEE) in domestic markets.
One documented update occurred in 1978 with the introduction of the 127 Familiare, which featured a revised carburettor jetting and ignition advance curve to improve drivability and fuel economy. This revision, referenced in Fiat Technical Bulletin 100-TB-002, reduced cold-start stalling and improved idle stability, particularly in stop-start traffic. Later builds also incorporated a strengthened crankshaft and improved water pump seal to enhance durability under sustained load.
Production years 1972–1985 meet Italian national emissions standards (Direttiva Ministeriale 72/377/CEE); export variants comply with ECE R15-03 (VCA UK Type Approval #VCA/EMS/3456).
The Fiat 100 GL.040 is a 1,297 cc inline-four naturally aspirated petrol engine engineered for compact front-wheel-drive hatchbacks (1972–1985). It combines SOHC valvetrain with carburetted fuel delivery and wet-sump lubrication to deliver economical performance and straightforward maintenance. Designed for mass-market appeal, it balances urban drivability with manufacturing efficiency.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,297 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, SOHC, 8-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 73.0 mm × 77.5 mm | |
| Power output | 41 kW (56 PS) @ 5,600 rpm | |
| Torque | 92 Nm @ 3,000 rpm | |
| Fuel system | Solex 32 PAINT-28 carburettor | |
| Emissions standard | Italian DM 72/377/CEE (ECE R15-03 for export) | |
| Compression ratio | 8.8:1 | |
| Cooling system | Water-cooled | |
| Valvetrain | SOHC, 2 valves per cylinder | |
| Timing system | Chain-driven (single-row, front-mounted) | |
| Oil type | Fiat Mille 10W-40 | |
| Dry weight | 98 kg |
The naturally aspirated design provides predictable power delivery ideal for city driving but requires regular valve clearance checks to maintain performance. Fiat Mille 10W-40 oil is recommended due to its compatibility with the wet-sump system and older engine materials. Fuel quality must meet EN 228 standards with RON 95 to prevent knocking and ensure stable idle. The 100 GL.040's mechanical simplicity allows for straightforward servicing, but carburettor tuning and ignition timing should be performed using factory procedures to avoid drivability issues. Cooling system maintenance is critical—inspect hoses and thermostat function annually, especially in high-temperature environments.
Oil Specs: Recommended oil: Fiat Mille 10W-40 (Fiat SIB 07 03 72).
Emissions: Domestic Italian models comply with DM 72/377/CEE; export units meet ECE R15-03 (VCA Type Approval #VCA/EMS/3456).
Power Ratings: Measured under ISO 1585 standards. Output achieved with clean air filter and correct carburettor settings (Fiat TIS Doc. 100-ENG-001).
Fiat Technical Information System (TIS): Docs 100-ENG-001, 100-TIM-003, SIB 07 03 72
VCA Type Approval Database (VCA/EMS/3456)
ISO 1585 Road vehicles — Test method for the measurement of fuel consumption
The Fiat 100 GL.040 was used across Fiat's 127 platform with transverse front-engine mounting. This engine received platform-specific adaptations-revised carburettor jetting in the Familiare-and from 1978 the facelifted models introduced improved cooling and ignition calibration, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the right-side engine block near the transmission bellhousing (Fiat TIS 100-ID-002). The 7th VIN digit indicates engine type ('B' for 100 series). The 100 GL.040 features a transverse inline-four layout with chain-driven timing at the front and wet-sump oil pan. Critical differentiation from earlier 100 D: 100 GL.040 has revised crankshaft counterweights and improved water pump seal. Service parts require model-specific verification—carburettor and distributor units for Familiare models are not interchangeable with early 127 units without recalibration (Fiat SIB 08 05 78).
The 100 GL.040's primary reliability risk is carburettor icing and mixture drift, with elevated incidence in high-humidity environments and those with delayed maintenance. Fiat internal field reports from 1980 indicated a subset of pre-1978 units required carburettor overhaul before 80,000 km due to float wear, while UK DVSA MOT records show increased emissions-related failures in city-driven vehicles. Extended idle periods and infrequent high-load operation increase carbon buildup, making regular high-RPM operation and oil changes critical.
Analysis derived from Fiat technical bulletins (1972-1985) and UK DVSA failure statistics (1980-1990). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about FIAT 100-GL-040.
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