1970 340 Balance Problem...Bottom Line

I will just add a few quotes from Larry Shepard's (#1 Mopar guru) book, How to Hot Rod Small BlockMopar Engines below. Mike

Forged Cranks-The forged crank is probably the most common type of crank used in racing. I was the only type used in the A engine family up to the early 70's. pg.15

Cast Crank-The A-engine cast crank was introduced with the '71 360 engine. By 1975, all A engines used a cast crank. The automatic transmission 340 engines got one in '72, however the manual transmission cars still used a forged crank until the end of '73. pg.15

The biggest drawback is that 340 and 360 cast crank engines need to be externally balanced. pg.15

Vibration Dampers-The cast crank 340 and 360 engines use a special offset damper in that a large flange is added to part of the damper. The forged damper is symmetrical. pg20

End quote

Hope this helps, Mike