Re: engine balance

Posted by Motiv8 On 2015/10/24 18:44:10

Reply to post 26,
All eng configurations have a different procedure. I'm assuming you're talking a 90 deg V8. That eng crank is not balanced separately. Actually no crank is ever balanced on knife edges. That is the wackiest idea that's ever been floated. A separate story.
A V8 is extremely sensitive to changes in rod or piston asmy wt. A (bob) weight is clamped on each V8 journal to represent a % of the component's wt. The oil in the crank's rod jrnl is also factored. A natural resonance peak is read on the crank w/ the bob wts attached, then spun. Each end of the crank will have a different plane of imbalance. It might look fine on knife edges but create thousands of lbs of imbalance force when running. The corrections are made on the counterwts. Sometimes removing wt if new parts are lighter or Mallory if they're heavier. Hope this is helpful. I'll answer about externally bal'd engs another time. David