Engine Balance Question

[beanhead]

I have a 440 rotating assembly with six-pack rods and Icon 9947 pistons. Balancing was previously achieved by drilling the forged crank. If this crankshaft was to be used with an LY-type rod and lighter piston, would it need to have weight added, or more drilling? Thanks!

 

[68Moparmaniac]

I have a 440 rotating assembly with six-pack rods and Icon 9947 pistons. Balancing was previously achieved by drilling the forged crank. If this crankshaft was to be used with an LY-type rod and lighter piston, would it need to have weight added, or more drilling? Thanks!

Would need to be checked again using the new rods and pistons to make up the bobweight

 

[dvw]

I have a 440 rotating assembly with six-pack rods and Icon 9947 pistons. Balancing was previously achieved by drilling the forged crank. If this crankshaft was to be used with an LY-type rod and lighter piston, would it need to have weight added, or more drilling? Thanks!

EDIT; When I read it at first I thought you were swapping to 6 pack rods. 6 pack rods are definitely heavier. Even a stock crank needs an offset balance damper and converter/flex plate. Which balancer and converter flexplate did it use previously? If you used the 6 pack stuff and it was drilled who knows what it is now. Do you have the old balance sheet?
Doug

 

[33 IMP]

Lighter stuff=less crankshaft counterweight

 

[Hemirunner]

I have a 440 rotating assembly with six-pack rods and Icon 9947 pistons. Balancing was previously achieved by drilling the forged crank. If this crankshaft was to be used with an LY-type rod and lighter piston, would it need to have weight added, or more drilling? Thanks!

More drilling since it’ll most likely be a lighter bobweight.

 

[beanhead]

Lighter stuff=less crankshaft counterweight

More drilling since it’ll most likely be a lighter bobweight.

Thanks, that answers it perfectly. I'm not doing it at this time, I was just curious which way you would typically go when using lighter parts with a given crankshaft.

 

[Lefty71]

Drill baby, drill!