Is 318 block same as 340 block?

No, the 318 block and the 340 block are not the same. The 318 block is designed for the Chrysler 318 cubic inch V8 engine, while the 340 block is for the Chrysler 340 cubic inch V8 engine. They have different bore and stroke dimensions, which affects their displacement and performance characteristics. Additionally, the two blocks may have different casting features and design specifications.