1) Please explain why my 402 is internally balanced and my 454 is externally balanced.

2) Why can I buy internally & externally balanced cranks for the 454 like a .250 stroker crank.

3) Why didn't the General internally balance the 454?

4) I'm going to make the 454 into a 496. Which is better, internal or externally balanced? :confused:

Originally posted by DaleP:
1) Please explain why my 402 is internally balanced and my 454 is externally balanced.

2) Why can I buy internally & externally balanced cranks for the 454 like a .250 stroker crank.

3) Why didn't the General internally balance the 454?

4) I'm going to make the 454 into a 496. Which is better, internal or externally balanced? :confused: =
1 The heavier the parts or the longer the stroke (the further radially from center the weight is) the more counterweight you need on the crank to balance it

2 The internally balanced crank has more counterweight added & uses a longer rod so the bottom of the piston does not smack the larger counterweight at BDC.
The externally balanced crank has less counterweight & can use a shorter rod but needs external weight or Tungsten (Heavy Metal) added to balance as the counterweights are not enough by themselves.

3 Because it is a lot cheaper to add weight outside the engine than to redesign the engine with longer rods & shorter compression heights & GM is in the business of making money :D

4 I prefer to internal balance whenever it is possible given budget constraints.
The closer you add weight to where the imbalance is the more effective it is as it tends to reduce "couple" which is a condition where you get a flexing motion along the crank if you just hang weight on the ends to balance when it is needed towards the center.
The higher the RPM the more important internal balancing becomes.