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Common shapes for the combustion chamber are typically similar to one or more half-spheres (such as the hemi, pent-roof, wedge or kidney-shaped chambers). The older flathead engine design uses a "bathtub"-shaped combustion chamber, with an elongated shape that sits above both the piston and the valves (which are located beside the piston).
A hemispherical head ("hemi-head") gives an efficient combustion chamber with minimal heat loss to the head, and allows for two large valves.However, a hemi-head usually allows no more than two valves per cylinder due to the difficulty in arranging the valve gear for four valves at diverging angles, and these large valves are necessarily heavier than those in a multi-valve engine of similar ...
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.
The Chrysler B and RB engines are a series of big-block V8 gasoline engines introduced in 1958 to replace the Chrysler FirePower (first generation Hemi) engines. The B and RB engines are often referred to as "wedge" engines because they use wedge-shaped combustion chambers; this differentiates them from Chrysler's 426 Hemi big block engines that are typically referred to as "Hemi" or "426 Hemi ...
As the piston approached top dead center, the angle of the crown combined with that of the head deck to form a wedge-shaped combustion chamber with a pronounced quench area. The spark plugs were inserted vertically into the quench area, which helped to produce a rapidly moving flame front for more complete combustion.
The Super Duty engine is 90-degree overhead-valve V8 with angled piston decks. The cylinder heads are flat and the pistons are crowned to create a wedge-shaped combustion chamber within the cylinder bore; the compression ratio is 7.5:1 for all models. They are typically governed to 3400 rpm.
These heads were cast iron units with new wedge-shaped combustion chambers and high-swirl valve shrouding. [8] Combustion chamber design was most important in these new heads: LA engine cylinder heads were given a full-relief open-chamber design, but the Magnum was engineered with a double-quench closed-chamber type.
The head is machined flat, with recesses only for inlet and exhaust valves, spark plugs, injectors and so on. The combustion chamber itself is contained within a dished depression in the top of the piston. The Heron head is suitable for petrol and diesel engines, for ohv and ohc valve-gear, and for small and large engine displacement capacities.