Dodge hemi small block

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Dodge did not have a V8 engine until one was developed specifically for the line in 1953 based on the 1951 Chrysler hemi design, but down-sized for these smaller cars. They have the smallest bore center distance of any hemi engine at 4.1875 in (106.4 mm). They do not share any major dimensions or components with the larger Chrysler and DeSoto hemi engines, or the Plymouth polyspheric ("poly") A engines. From 1955-58 lower performance versions of the Dodge hemi were introduced by substituting less complex poly (single rocker shaft) heads and valve train parts, including one variant only built as a poly (259"). These were used in low-line 1955-58 DeSotos and Dodges, and 1955-56 high-line Plymouths.

(NOTE: The DODGE Hemi engines mfd. during 1950's had no harmonic balancer to speak of- they had a front hub of sorts on the crankshaft that slid on, attached to pulleys, and held on by one large bolt/washer- this hub/pulley setup is very light, and has almost zero harmonics absorbing/dampening capability. These engines have been known to break crankshafts for no other apparent reason- it is highly recommended that during any rebuild of the Dodge hemi/poly engines of the 1950s, the crankshaft be carefully MAGNUFLUXED for cracks first, and an aftermarket HARMONIC BALANCER purchased from an aftermarket source-they are available from HOT HEADS. With the addition of a modern balancer, the DODGE engine is as good as any-and actually quite good considering it's smaller/lighter than the Firepower/DeSoto engines, while still being able to reach 325+ CID in stock form. Removing the harmonic balancer from any modern engine, would cause the crankshaft to break in short order. The FIREPOWER and DESOTO engines do have an OEM balancer.)


The Dodge introduced the 241 cu in (3.9 L) version in 1953. Bore was 3.4375 in (92 mm) and stroke was 3.25 in (83 mm). It produced just 140 hp (104 kW).


The 270 cu in (4.4 L) was used in the 1955 and 1956 Dodge high-line (premium) vehicles. Bore was 3.625 in (92 mm) and stroke was 3.25 in (83 mm).


In 1956, the displacement was raised to 315 cu in (5.2 L) with the same bore and a longer 3.80 in (97 mm) stroke and a taller raised-deck block.


In 1957-58 the bore was increased to 3.6875 in (94 mm) to 325 cu in (5.3 L) with the same 3.80 in (97 mm) stroke.