Description: Bowtie engine blocks from the professionals at GM Performance. These GM Performance Parts Bowtie big block Chevy cast iron engine blocks have all 8620 steel main caps and are CNC-machined. They are race-prepared blocks that feature blind head and accessory mounting bolt holes, a deck configuration that enables the use of any big block Chevy cylinder head, and cylinder bores that(more)

Description: Bowtie engine blocks from the professionals at GM Performance. These GM Performance Parts Bowtie big block Chevy cast iron engine blocks have all 8620 steel main caps and are CNC-machined. They are race-prepared blocks that feature blind head and accessory mounting bolt holes, a deck configuration that enables the use of any big block Chevy cylinder head, and cylinder bores that may be safely bored to a 4.600 in. maximum diameter, while maintaining a .250 in. minimum cylinder wall thickness. The GM Performance Parts Bowtie big block Chevy cast iron engine blocks differ from the production-machined Bowtie versions in certain areas--they start from raw castings and are not "conversions," and they use a rear seal adapter to convert the Gen V/VI one-piece rear main seal to a Mark IV type 2-piece seal that facilitates the use of a widely available Mark IV style crankshaft. In addition, 8620 steel bearing caps are put in all locations to further increase the integrity of the bottom end. The intermediate caps also feature 16 splayed outer bolts, which anchor the caps into the strongest section of the blocks and prevent bearing cap movement under high loads. The main oil gallery on these blocks is relocated and enlarged to a 9/16 in. diameter to allow increased oil flow through the block. The CNC race-prepared Bowtie blocks have inner head bolt bosses, which allow better retention of cylinder heads in high-horsepower applications when the cylinder heads "lift" from the blocks due to high cylinder pressures. Build a reliable, high-horsepower engine with one of these GM Performance Parts Bowtie big block Chevy cast iron engine blocks. (minimize)