Rebuilding an early Hemi engine

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.

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.

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.  

*Chrysler 331 hemi heads can be used on the 301 and 331 Polys, and 354 hemi heads can be used on 354 Polys.

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.

==Related resources==

*[http://www.hotrodsandhemis.com/Rebuild/HemiRebuild.html Hemi rebuild]