Reworded questions...
For example, what does balanced to 28oz mean when describing an engine?
A: It means that the engine uses a 28oz imbalance (externally balanced). This typically means that the harmonic balancer and flywheel/flexplate are 28oz items.
Re-Q: But what do you mean, that the h-b and flywheel/flexplate are 28oz items? And the engine uses a 28oz imbalance? You know me Brent, I'm slow on the uptake.
Q:How does this affect clutch choice?
A: It doesn't. However, some guys want to have the pressure plate balanced with their rotating assembly as an option.
Re-Q: I can't find the email, but I thought you asked me awhile ago what engine imbalance for a particular flywheel or clutch selection?
Q: Also what is external balancing?
A: An externally balanced engine uses a weighted harmonic balancer and/or flywheel to keep the engine in balance.
Re-Q: I take it this is the quick,cheap version of engine balancing. Is this static or dynamic?
Q: How does a harmonic balancer work?
A: It uses different materials, such as rubber, fluid, polymers, etc. to help eliminate the vibration harmonics out of an engine.
Re-Q: Does an engine that is internally balanced have/require a h-b as well?
Q: What items are subjected to internal balancing? And is this balancing static or dynamic?
A: Everytime you balance a rotating assembly, it's dynamic. Go to YouTube and look for some rotating assembly balancing videos. The crankshaft is placed in a balancer and spun up to rpm. There are bobweights bolted to each rod journal which simulate the weights of the pistons/rings/rod bearings/rods/parasitic
oil, etc.
Re-Q: Excuse my ignorance, but is the rotating assembly just the crank, or is it the crank/rods/pistons assembly?
Q: Is material typically added (weights) or removed?
A: It depends on which setup you have. You can do it either way, although the crankshaft manufacturer will design the counterweights on the crankshaft so that a target bobweight will be used.
Re-Q: Does the crank manufacturer (say, Scat?) balance his cranks, or does he leave that for the engine man?
Q: Do tailshafts normally need balancing?
A: If you're talking about a driveshaft, then yes.....always.
RE-Q: Halfshafts too?
Q: At what rpm point does extensive/comprehensive balancing become essential?
A: There's really not an "extensive" balancing. It's either balanced or it's not balanced.
Re-Q: OK...is there a a rpm level at which it is advisable to have the crank and rods and pistons all dynamically balanced?
Apologies if this is tedious going, but there'a a lot here that I understand a little, and don't understand a lot. Thanks for the time spent in replying. It's appreciated.
Cheers,
Glen