Your machinist is 100% correct. Ballancing each counterweight with Mollory metal against the weight of the appropiate piston/rod assmbly is the best way to ballance an engine, (internal ballanced). When a crank is ballanced externaly, each counterweight is still partialy unballanced and the difference is taken up at the flywheel/front ballancer. This puts the "assembly" into ballance, but the unballanced loads between the crank pins and the ballance weights have to travel through the crankshaft to get there. This puts more load, (and harmonic stress as the shock loads travel back and forth down the length of the shaft), on the crank then just having to transmit the torque from the crank pins to the flywheel flange.
That being said, automotive crankshafts are designed to carry this under normal circumstances. Unless you are building more HP into the engine then the crank was designed to handle, external ballancing is fine and acceptable under most circumstances.
0 ballance is just that, stock ballance is OFF ballanced 20oz on your 289. You can buy 0 ballanced aftermarket flywheels for use on internaly ballanced engines, but if what you are looking for is flexibility, stay with the 20oz flywheels. That way you can use anything that is designed for a SB ford and just bolt it on.
If you are building a very high RPM race engine, go with the 0 ballance.
Hal
Love hard, drive fast, wear your seat belt.
PS, that's my 'bird...... My Mustang is too ugly to take pictures of yet........*G*.
http://www.teleport.com/~cosa/bird2.jpg
That being said, automotive crankshafts are designed to carry this under normal circumstances. Unless you are building more HP into the engine then the crank was designed to handle, external ballancing is fine and acceptable under most circumstances.
0 ballance is just that, stock ballance is OFF ballanced 20oz on your 289. You can buy 0 ballanced aftermarket flywheels for use on internaly ballanced engines, but if what you are looking for is flexibility, stay with the 20oz flywheels. That way you can use anything that is designed for a SB ford and just bolt it on.
If you are building a very high RPM race engine, go with the 0 ballance.
Hal
Love hard, drive fast, wear your seat belt.
PS, that's my 'bird...... My Mustang is too ugly to take pictures of yet........*G*.
http://www.teleport.com/~cosa/bird2.jpg
