Editing Rebuilding an early Hemi engine

The early Hemi engine is being rediscovered by enthusiasts all over the country. For some, nothing can match the class and power of an early Hemi under their hood. However, before tackling an early Hemi engine rebuild, several factors must be considered. The high cost of Hemi rebuilds, and the difficulty in acquiring parts, plays a significant role for most rebuilders. ==Cost and parts availability== It will cost 2 to 4 times as much to rebuild one of these motors than it will your everyday small block Chevy. This difference in price has been the cause of many a Hemi just sitting in the corner of a garage somewhere instead of rumbling down the street in all its glory. However, it is very rare to find an early Hemi in a wrecking yard that can't be rebuilt. Chevy and Ford fans aren't so lucky. Depending on the size and location of the motor, expect to pay anywhere from $300 to $1500 for an engine to rebuild. After price, the second item you need to be concerned about when rebuilding a Hemi is parts availability. Stock rebuild parts are widely available. However, performance parts for some of the less popular Hemis can be a real challenge to find. Epecially the DeSotos -- performance parts for these motors are virtually non-existent. Some factory equipment was supplied way back when, but it's very difficult to come by. For example, a DeSoto factory dual quad manifold with carburetors and linkage intact could fetch $2000 or more. Limited performance equipment is available for the Dodge Hemi, but far more parts are available for the Chrysler 331-392 series than any other. The good news is that as these engines are being rediscovered and as they become more popular, manufacturers are beginning to re-introduce performance parts they stopped making 20 or 30 years ago. Newer companies are providing parts and services for the early Hemi enthusiast, and more are sure to follow. 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. ==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: *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. 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. 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. 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. *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== The '51-'53 Chrysler 331's (and some of the '54s) had an extended belhousing cast into the back of the block, which limits transmission choices. Some outfits have reintroduced adapter kits which allow the GM 4-speed to be bolted to these blocks. These adapters are a welcome addition to the parts bin for many enthusiasts. For years, these extended blocks were considered useless (except for spare internal parts) and many of the blocks were trashed by short-sighted hot rodders. DeSoto, Dodge and Plymouth never produced Hemis or polys with the extended bellhousing. In '54, Chrysler fell in line with its other divisions and introduced a more conventional belhousing design, making the installation of modern GM and Chrysler automatic transmissions much easier. However, adapters are still required; they're available from several sources, but be prepared to pay between $300-$400 for a good one. ==Cylinder heads== Hemi cylinder heads were cast iron, as were the intake and exhaust manifolds. 2 bbl. and 4 bbl. versions were available while the high performance line usually had a dual 4 bbl. low rise manifold equipped with early Carter WCFB carbs. ==Hemi parts suppliers== *PowerPlay *Hot Hemi Heads *Kanter Auto Parts ==Related resources== *[[Chrysler Hemi engine history]] *[[Early Hemi engine identification]] *[http://www.hotrodsandhemis.com/Rebuild/HemiRebuild.html Hemi Rebuild]

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