So i just received my balanced rotating assembly from cnc-motorsports in the mail. Everything was nicely packaged and Clint at cnc was very helpful. I noticed however that the rods and pistons are not assembled (they are floating pin so i can assemble 'em myself, thats not the problem) however i was under the impression that once an assembly was balanced the rods/pistons must remain together, and that the rod-piston assembly must remain at the same crank journal. I have a bob weight sheet, and the pistons/rods all have their respective weights written on them, but nothing to indicate their respective positions. So i have no doubt that the assembly was balanced, i'm just concerned about reassembling it the wrong way.

Am i totally off base here? are all the component's weights simply averaged together when balanced?

-Zander

 

In a proper balancing job, all the components are weighed. The heaviest pistons, rods, etc., then have weight removed from them in non-critical strength areas so they all weigh the same as the lightest part. Then the bobweights are established, and the crank balanced.

 

Thats good news. Out of curiosity how closely should individual parts be balanced? +/- 1g? +/- 0.1g?

-Zander

 

Usually to within half to one gram of each other.