Engine Balancing Problems

Some forged cranks are for 273 they do not have the 1 inch holes through the journals. The 340's having a heavier rod and piston had this material removed. The 273 cranks are stonger but need to be used with a lighter rod and piston combo. Could be the bob weight they can't get right. They will need to drill the journals or use a lot of mallory. These holes are the weak link on the stock 340 forged cranks. One reason to use a 273 for standard stroke. or a Callies for a stroker. Elliminate the flex under extreme hard launches.