What is the stroke on a 340 vs 318 crank. I know all small block rods are the same length. arent they both a 3.31 rod ratio? If so the only advantage the 340 has over the 318 is bigger bore size and a forged crank
The cranks have the same stroke, the rod ratio is the same. The difference in displacement between the 318’s and 340’s was entirely on the bore diameter. And 318’s came with forged cranks for awhile too depending on the application.