When someone say "Engine is balanced"... What does that mean? Is it the crank? Crank and rods? The whole rotating assembely? What type of machine do they use to balance engines? I have seen crank balancers, but i have never seen a full engine balancer? Is there such a thing? Some please shed some light on this topic.

Thanks.

 

Well they mean the entire rotating assembly. A machine shop can balance the entire assembly by weighing each rod and piston, then coming up with correct bobweight (small weights attached to crank journals) to put on the crank. The crank is then spun and material added or removed from the crank to balance the assembly. Material can also be removed from the rods and pistons to dial everything in properly.

some engines are external balance, and requre you to include the dampner and/or flywheel too in order to balance the rotating assembly. (400 sbc was this way if I recall correctly.)

 

What machine or tools are needed for engine balancing? From what you said i think a Calculator and a crank balancer machine? Is that right?

 

http://www.sunnen.com/product_detail...&catId=68&lnk=

one example of a crank balancer

 

A crank balancing maching is expensive, something a major engine builder would have. I can't imagine balancing a crank by hand. I'm sure it can be done with LOTS of time, some tools, and a good amount of math.

 

More math than I would want to mess with that is for sure.

 

In order to properly balance an engine you need to weigh each component. Match the assemblies and spin balance the entire thing to RPM's matching what you'd find in use (say 7k). The company I work for makes devices for spin balancing items from .01 of a gram to 100 tons. (think hydroelectric dam impellers) within .001 of a gram. A Properly balanced and blueprinted engine is a thing of beauty but I would bet you can't do it effectively without the right equipment.