91GTABird

What is exactly balanceing and blueprinting an engine? I know some basics of balanced (equally weighed parts)but what is Blueprinted (documented parts installed?)? Whats the difference in internal and externall balanceing?

ede

internal balance the mass of the piston and rod is balanced by the crank shaft counter weight

external balance the mass of the piston and rod can not be balanced by the counter weight alone so weight is added to the dampner and or flywheel. external balance engines tend to have short rods that would cause the piston to hit the counter weight as they moved in the bore.

blueprinting is assemblying to a spec, or to duplicating the same spec for everysame part, such as bearing clearance or end gap

balancing is equallizing the mass of the rotating and recipricating parts

MrDude_1

ede is 100% correct, but i think i can explain the balancing clearer for any noobs.


in otherwords:

if you took a intrnally balanced engine, took everything off the outside of it, including the dampener and flywheel, and then spun it really fast .. it would spin perfectly balanced... everything needed to balance it is internal...

do the same thing with a externally balanced motor... and it will shake its self like crazy.. the weight isnt balanced so it trys to bounce around...kinda like a vibrator.. if youve ever took one of thoes apart, you'll see that its just a electric motor with a big weight hanging off the end of it..

if you look at the dampener and/or flexplate for the externally balanced motor, you'll see that it has weights on it.... thoes weights counteract the offset of the motor...

so if you bolted the dampener and flywheel on our imaginary externaly balanced motor, it would spin smoothly, just like our internally balanced one.


is that clearer?

19doug90

well ive heard of kids taking apart their fathers tools to see how they work....dont think i want to know what you spent your childhood doing!!!

MrDude_1

bwahahahaha, i knew id get a comment if i threw that in

when i was orignally typing it, i was thinking of thoes massager vibrator thingys... but i knew how most of ya would read that


whats really funny about that is my moms a nurse, and nurses tend to get free stuff from drug reps... pens, pads, lil toy things, all with the drug name on them... well they were giving away massager things.. so i took like....20 of them.... took most of them apart for the motors.. i even put one in my record breakers car.. (remember thoes?) lol

91GTABird

Thanks guys (the mature ones) Ede that was an ecellent explanation, but just a little over my head. Mr. Dude if it wasnt for the vibrator thing i wouldnt have understood ede. That was a great comparison. Thanks alot Mr. Dude and Ede!

formularpm

Just a little extra info

400s are externally balanced
'86-newer 350s are also externally balanced
Most others are not

91GTABird

So is internally balanced better, or just more accurate? Do all internally balanced motors not have a Damper? Is a Fluidamper a better one than a conventional one?

Formula
Can any sbc or bbc be balanced either way?

MrDude_1

internally balanced CAN BE more accurate, however as they come from the factory, the tolorances are about the same as externally balanced... its easier for the factory to make them externally balanced, so they started doing so again..

all motors have a dampener, however internally balanced ones have a balanced dampener with no extra weight on it. it doesnt need to counterbalance anything..

Fluiddampeners are great... but pricy... yes they are better... most stock dampeners are only really effective in a RPM range... fluid dampeners work at every RPM.


MOST exterally balanced ones can be made internally balanced by a machine shop. they drill holes in the counterweights and add heavier mallory metal... mallory metal weighs alot more for its size then steel or iron, so using that they can usually get it internally balanced... however mallory metal is expencive... so its a costly thing to do.


ive never heard of anyone wanting to make a internally balanced motor externally balanced... athough i suppose it probly could be done by shaving the counter weighs just right...