okay now im confused. I did a few searching and came up with people arguing about balancing their motors. so far ive learned nothing...

so lets make it easy;
I put together my motor already. my question is this:
All of my connecting rods are within +/- .5 grams. directly from Eagle.
All of my pistons are within +/- .3 grams. Directly from TRW.
My crankshaft was balanced by the machine shop to "match" my rods/pistons.
My Balancer is a "Fluidamper, Street Damper"
Now for the questions:
Does this make my motor "internally" balanced?
<b>My crankshaft was balanced to "match" my rods/pistons.
</b>
What does this mean? They added metal and removed some too, but I cant figure out why? was it to just make the crankshaft balanced on its own?
<b>My Balancer is a "Fluidamper, Street Damper"</b>
Was this a good choice? why do they have several different sizes and "external" and "internall" balance dampers? What the heck is the difference?

 

just like it says, internal the weight is added or removed internally and aexternal balance has the weight added orremoved externally, from the dampner and flywheel. external engines are balanced to some extent internally, as you noted the rods and other parts have to weigh something and be withion something no matter if it';s internal or external.

 

The crank has counterweights, which have to match the mass of the big end (not the total weight) of the rods. That's what they did to your crank to "match" it to the rods. Pistons don't matter to the crank balance; they don't rotate, only reciprocate, so as long as they're all the same, you're good. Same for the small end of the rod: it doesn't rotate either, it only reciprocates. So as long as all of them are the same, they're OK, and the crank balance does not care about them.

If you use rods that are too short to allow enough room for the counterweight, you can't internally balance a motor. Instead, some of the mass for some of the counterweights has to be located in the balancer or flywheel or both. SBC 400 and BBC 454 both have this situation. If you don't have the crank from one of those, your motor is internally balanced. The 1-piece RMS motors are slightly externally balanced, but only at the flywheel end; all flywheels for them are the same balance, and the crank damper is neutral just like older motors.

 

When they remove metal and add metal to your crank they are replacing the crank metal with a heavier metal to make the weight come out right.
When I get a motor balanced, 350ci sbc, I give the balancer, crank, rods, pistons, and flexplate(flywheel) to my engine guy and he balances it.
Internally and externally balanced motors are diffrent animals. 350 ci sbc is internally balanced. 400 ci sbc is externally balanced. You can tell by the flywheels and balancers. They have more metal counterweights on them.

 

ok it makes some sense now. But then what does the phrase:

"Balanced and Blueprinted" mean? is it the same thing?

 

"Balancing" is balancing. An assembly is either balanced, or not.

"Blueprinting" is the process of returning an engine to original design specifications (NOT production tolerances) so that every part is dead-on the specification. It can also be the process of modifying an assembly to a different design specification if the builder desires something other than the stock specification, but the process is the same and requires attention to the smallest detail.

In some rare instances, a production engine may indeed be "blueprinted" if by some chance all the tolerances of all the parts happen to fall in the center of their allowable ranges. Statistically, this MUST occur with at least some engines that leave the factory. This probably explains why some engines leave the factory with what seems to be better than average power output, and others are delivered with less than average output. Since the tolerances are additive, if all the tolerance goes the wrong way and happens to come together in the same assembly, you have what is commonly referred to as a "lemon".

It seems that in more recent years, the factory specifications are getting tighter, and the ability to hold those tolerances is getting better, so that more and more production engines are being produced closer to that "blueprint" specification.

"Blueprinting" in the rebuild field simply means removing all the variation and tolerance. It doesn't always mean "better", and is a loosely and frequently misused term.