Unique valvegear

Aurelio Lampredi, Franco Rocchi and Walter Salvarani joined Ferrari together in 1947. During the war, they had worked at aircraft maker Officine Reggiane, designing an inverted W18 engine. With four valves per cylinder, direct fuel injection and a three-speed supercharger, this ambitious engine was expected to produce as much as 1,810 bhp at 2,900 rpm. Once at Ferrari, the three engineers brought some of their aeronautical experience to bear.

The W18, of which only three or four prototypes were built, utilized narrow cam lobes working against roller followers. Lampredi used this principle for his four- and six-cylinder engines of 1951-55.

For the 500 F2, Lampredi went one step further and developed unique valve gear. He kept the hairpin-type valve springs introduced by Gioacchino Colombo, creator of the first Ferrari engine, which permitted short and light valves. Above each valve Lampredi placed a steel-tipped light-alloy follower with a circular top, into which was set a large-diameter roller.

Beneath the circular top of each cam follower were two concentric coil springs, whose only task was to keep the roller in steady contact with the cam lobe. In this way, the function of controlling the tappet was separated from that of closing the valve. Keeping the roller-faced tappet in contact with the cam lobe was the job of the coil springs; the hairpin springs only had to close the valve itself.

This unique valve gear virtually eliminated cam and valve problems—then often suffered by rival teams—from the Ferrari lexicon, and contributed materially to the reliability of the 500 F2 single-seater. From 109 starts in 1952-53, these cars recorded only 18 retirements for mechanical reasons, and scored 30 wins in the 33 races they entered.

Screwed-in cylinders

Both of Lampredi’s new engines, the 375 F1 V12 and the 500 F2 four, were made even more reliable through a shared structural feature: individual cylinders that were screwed into the cylinder head. Screwed-in cylinders eliminated the problems associated with a gasket at the joint between the block and head—an important consideration in a highly stressed racing engine.

In addition, this layout allowed each cast-iron cylinder to be separately machined. This meant they would be precise in diameter and thus could be closely spaced within the engine, reducing both weight and bulk.

The screwed-in cylinder wasn’t new. As early as World War I, it had been used to make aircraft engines as light and efficient as possible. It was used by some of the most progressive automakers, such as Alfa Romeo, but only for a few advanced racing engines at the end of the 1930s. Ferrari’s innovation was to hugely expand the use of this previously exotic technology.

The Maranello firm transitioned toward this with Colombo’s 1949 design of a four-overhead-cam version of the 1.5-liter V12 supercharged Formula 1 engine. Although this had a conventional parting between cylinder head and block, each cylinder was attached to the head by four studs surrounding its combustion chamber. The bottom end of the cylinder hung freely in the crankcase and was sealed by O-rings.

Lampredi’s four-cylinder Type 500 carried the concept further by using cylinders that were screwed directly into the head. This permitted the water jackets to be cast integral with the head and thus to be bolted directly to the crankcase. Through 1955, screwed-in cylinders would be used in Lampredi’s racing engines: inline fours as large as 3.5 liters, six-cylinders as large as 4.4 liters and V12s built in sizes up to 4.9 liters.

Furthermore, Ferrari was the first automaker to utilize such cylinders in a road car. The Lampredi V12 powered the Americas and Superamericas from 1951 to ’59, as well as the 1964-66 500 Superfast, which featured a 4,961cc version. Then as now, Ferrari’s advanced racing technology made its way onto cars that could be used on the highway.