Rebuilding an early Hemi engine
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The Chrysler Hemi had a cast iron block. Thin wall casting techniques had not come into practice in the early 50's, so these motors were quite heavy for their size. All were produced with 2 bolt main caps, and forged crankshaft and connecting rods. Most engines came with cast aluminum pistons and hydraulic valve lifters, with the exception of some of the high-performance versions, which left the factory with forged pistons and solid lifters. These motors can be identified by four bumps in the valve covers between the spark plugs. | The Chrysler Hemi had a cast iron block. Thin wall casting techniques had not come into practice in the early 50's, so these motors were quite heavy for their size. All were produced with 2 bolt main caps, and forged crankshaft and connecting rods. Most engines came with cast aluminum pistons and hydraulic valve lifters, with the exception of some of the high-performance versions, which left the factory with forged pistons and solid lifters. These motors can be identified by four bumps in the valve covers between the spark plugs. | ||
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| + | ==Parts interchangeability== | ||
| + | Each Chrysler division (Chrysler, Dodge, DeSoso, and Plymouth) produced their own version of the Hemi. Only a few specific parts will interchange, including the following: | ||
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| + | *All '51-'53 Chrysler front covers will fit all DeSoto engines. | ||
| + | *All '56-'58 Chrysler front covers will fit all Dodge engines. | ||
| + | *Dodge high block and DeSoto high block connecting rods will interchange. | ||
| + | *Distributors, oil pumps, and bellhousing/starter mounting flange plates will interchange, except for the extended block versions. Keep in mind that these flanges vary in thickness depending on the transmission used. | ||
| + | *Valve stem diameter is the same in all engines and length is very close, so the larger diameter valves from the bigger engines can be used to improve the breathing of the smaller motors. | ||
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| + | Within divisions some parts will also interchange. Although some low block and high block cylinder heads will interchange, care must be taken when considering certain combinations. For example, 392 heads are wider than earlier low block (332-354) heads, allowing the earlier intake manifolds to be used on stock 392’s, However, when using early (low block) manifolds and heads on a 392 block, spacers must be used because the higher deck height of the 392 will align the intake manifold mating surfaces too far apart. Conversely, 392 heads won't work on a low block (331 or 354) hemi unless you use a log manifold, because the lower deck height of the 331-354 combined with the longer intake runners in the 392 heads will align the intake manifold mating surfaces too close together to use a standard manifold. | ||
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| + | There are also dowel pin diameter considerations to deal with as well as mismatched coolant passages in the lower corners with some head/block configurations. As an example, ‘56 low block (354) heads will not easily fit on a ‘54 or earlier low block (331) for these very reasons. | ||
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| + | DeSoto and Dodge heads won't interchange between high and low blocks without spacers and a lot of extra work. The manifold mounting angles are different between high and low blocks so swapping heads can be a nightmare on these motors when it comes to finding a compatible intake manifold. This is especially true with the DeSotos because of the lack of availability of any high performance aftermarket manifolds. The Dodges can use a log manifold to solve this problem, if you can find one. | ||
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| + | *Hemi heads will fit poly blocks of the same family, but will not fit "A" series poly motors. | ||
| + | *Chrysler 331 hemi heads can be used on the 301 and 331 Polys, and 354 hemi heads can be used on 354 Polys. | ||
| + | *No camshafts will interchange between low and high blocks of any engine family because of differing lifter bore angles. | ||
==Transmission choices== | ==Transmission choices== | ||
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