The mysteries behind engine balancing?

How do you mean? Pertaining to balance issues? Im running my 273 crank in the same year 318, no issues at all, only 150 miles on it so far but problems usually show up right away, IME. MT:burnout:

I may have been thinking of 340. According to this at least some 273's and 318's used the same crank.

I actually used a 273 crank in a 340, back when "I didn't know better"

https://books.google.com/books?id=c...e&q=mopar 273, 318, crank interchange&f=false