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Motown Cast Iron Blocks

   At first glance, one of the more noticeable differences between the World Motown and OEM Chevrolet blocks are the “bulges” at each cylinder. That’s because the “Motown” has thicker cylinder walls, and the water jackets have been expanded to provide required cooling. The Motown block can be bored to max of 4.200". DO NOT EXCEED.

   Other physical differences between World’s Motown block and an OEM casting include creating 1" thicker “bulkheads” to provide ample support of the front and rear mains, and the addition of special bosses for front-feed oil systems and rear dry sump scavenging.

   The Motown is equipped with nodular iron main caps, precision registered with dowel pins and secured with beefy 1/2" bolts. You should know that nodular iron caps are far superior to the OEM caps, as well as have advantages over aftermarket steel billet caps. That’s because the nodular iron will expand at the same rate as the block, promoting superior main bearing life.

   Another feature is the use of standard Chevrolet cam bearings throughout. No need to buy several boxes of bearings (as with other aftermarket blocks) and pick out the same-sized ones because the block isn’t step-bored.

   Solid pan rails are used to ensure proper sealing. Crankshafts with strokes up to 4.000" can be used without clearancing the block. Stock-type oil pans can be used (no special wide-rail designs).

   The mains are line-bored. All head bolt holes are blind tapped and the lifter bores are indexed (standard height lifters can be used). Most importantly, the block is manufactured in its entirety (to QS-9000 specifications) using only two fixturing operations. There’s absolutely no tolerance “stacking” as with factory blocks, that are made on an assembly line and passed from one machine to another.