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The Lotus 907 was an engine designed and manufactured for automotive applications by Lotus Cars. It was an original design, dual overhead cam, 16 valve all alloy powerplant. It displaced 1973 cc and developed approximately 144 bhp (107 kW) with dual side-draft Dell'Orto carburetors or horizontal Zenith Stromberg carburetors for US cars. It was nicknamed "The Torqueless Wonder" for its lack of bottom end but good high end horsepower.
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History
The Lotus 907 was the first production variant of the Lotus 900 series engine and the Jensen-Healey was the first production car to receive the Lotus 907.
It is said that when Vauxhall unveiled its new slant-four engine at the 1967 Earls Court Motor Show its bore centers were exactly the same as those proposed by Lotus. Colin Chapman immediately negotiated a deal with Vauxhall to buy some of their cast-iron blocks so that development of Lotus' own aluminum cylinder head could be sped up to produce the 907 engine.
Lotus Esprit
The original Lotus Esprit, the Lotus Elite, and the Lotus Eclat were fitted with a 907 engine. Developments to this engine resulted in the subsequent type 910, the 912 and the V8 type 918.
Problems
Oil leakage was commonplace in the first few years of production, though the problem was eventually addressed by aftermarket cam cover gaskets made from reusable rubber. Later 900 series Lotus engines included a revised cam tower that greatly improved the cam cover sealing design. The later cam towers can be retrofitted to the earlier 907 engines. Early Jensen-Healey engines (1972–1973) had oil supply issues that made the oil pressure slow to build on start-up. Some early engines also had issues with oil drainage which resulted in too much oil being retained in the cam carriers. Differences between early and late 907 engines included rope seals for the rear of the crankshaft versus regular spring-loaded rubber lip seals for the rear of the crankshaft on later 907 engines.