Difference between 360,340 and 318

318 has smaller main caps, and weaker rods if we are talking stock blocks with stock parts, the 340 starts out with better rods, stronger caps and a forged crank, 360's are cast, some of the early 318's are forged also. if its low HP they will all hold up, if high hp then the 340 in stock form is better. for those in love with the 318 they are great motors but in a high hp build i would want the better rods and thicker webs and caps on the 340.