All MEL engines had wedge-shaped combustion chambers formed between a flat head surface and an angle milled block deck (10 degrees off square with the bore axis), with the piston top determining the compression ratio and combustion chamber shape, similar to the Chevrolet Big-Block 348 combustion chamber, also introduced in 1958, and the later 409 and 427. Unlike the Chevrolet, which had staggered valves and scalloped or M shaped valve covers, the MEL valves were inline with shaft mounted rocker arms like the FE model Ford engines which were introduced at the same time. As with the previous generation V8s, an open runner intake manifold was used, requiring the use of a stamped steel lifter valley cover similar to that of the Pontiac V8 engines. Also, the intake manifold provided no exhaust crossover passage to warm the air-fuel mixture. Further MEL engines employed two individual thermostats, aimed to improve the regulation of the engine's coolant temperature.