Designed by Aurelio Lampredi, the Fiat 124 engine first appeared in the all-new Fiat 124 in April 1966. The in-line four-cylinder engine comprised an iron block with an aluminium cylinder-head with pushrod actuated valves. The belt-driven design was ahead of its time when introduced. The engine remained in production until the 1990s in Latin America, although European production ended with the Fiat 131 in 1984. It did have a longer life in its twin-cam iteration, which continued in production until 2000. While originally of an overhead valve design, an overhead cam version was developed for Fiat's Brazilian arm in 1976 and in 1981 it was added to the facelifted 131 in Europe as well. The capacity was initially 1,197 cc (in the Fiat 124), but eventually ranged between 994 cc and 1,585 cc. There was also a 1.3 liter diesel iteration, only built in Brazil but exported to Europe as well. The last versions of this engine to be built was the one-liter engine developed in Brasil for the Fiat Mille.
The Fiat 124 series engine was produced in a number of configurations differing in stroke and bore but maintaining a standard bore-spacing. The first model (124 A.000) was near square, using a bore of 73.0 mm and a stroke of 71.5 mm to produce a displacement of 1,197 cc. A larger 1,438 cc version arrived in October 1968, in the 124 Special. This has an 80 mm bore. The bore was increased to 76 mm to give a displacement of 1,297 cc for the 131, which was also available in a 1.6 liter version (84 mm bore). A variety of other bores were available, and the Brazilian engine was also developed with both short and long-stroke versions of 994 and 1,497 cc respectively.
The 1.3 was later bored out by 0.1 mm, to nudge the displacement above 1.3 liters. This allowed Italian motorists to drive a full 140 km/h (87 mph) on the autostrada, rather than the 130 km/h (81 mph) which was allowed for cars under 1.3 litres.
The 124-series engine has five main bearings, an iron block and an alloy head. Intake and exhaust are both located on the right-hand side of the engine. The Brazilian engine was the first overhead cam version developed, first shown in autumn of 1976. It took nearly five years before the Italian-built engines were changed to such a design. The Brazilian engine, which first appeared in a 1.05 litre version, has chrome-treated exhaust valves with stellite seats, for increased durability. The Brazilian engines were also exported to Europe in large numbers, both for the 127, Ritmo, and the later Uno (diesels only) as well as a few Milles/Dunas/Elbas sold by Innocenti.
The diesel, originally of 1,301 cc, was later bored out to 78 mm (for a total displacement of 1,367 cc) and was also available turbocharged. There was also a two-litre pushrod version (6132 AZ 2000) for the 1974 to 1982 Fiat Nuova Campagnola, this has the 84 mm bore of the 1.6 but combined with a 90 mm stroke.
List of vehicles utilising variations of the Fiat 124-series engine (incomplete).
Fiat 124: 1966-1974
Fiat 131 Mirafiori: 1974-1981 (longer for the Weekend/Estate)
Fiat 131 Mirafiori: 1981-1984
Fiat 127: 1977-1987 (export version for Europe)
Fiat 147/Spazio: 1976-1987
Fiat Oggi: 1983-1985
Fiat Uno/Mille: 1984-199? (Latin American version)
Fiat Prêmio/Duna/Elba: 1985-199?
Fiat Ritmo: 1979-
Innocenti Mille: 1994-1997
Fiat 127: 1981-1987 (export version for Europe)
Fiat 147/148/Spazio: 1981-1990 (also built in Argentina)