I don't have my book handy to look @ main journal size difference if there is one, BUT all main caps are line bored to the specific block they were machined with when they left the factory.
hi, the 340 and 318 caps have same bore dia. the 340 cap is taller compared to 318 cap for windage tray use. however, don't throw the caps away! If you swap caps, main bores have to be align bored. don't align hone!! align honing will not straighten the bore, just hones whats there. plus moves crank up and creates loose timing chain slop. just food for thought
