Hi! have a Q on this had rebuilt my 396- .060 over steel crank cast rods -heads installed 2.18/1.88 valve new guides and sprng,vlvs shimmed. 7/16 psh rds. anyway did have it balanced G.M. balanced shop says checked # of 1 rod & # 1 piston set to get bob # and I seen were he added weight to the crank in a couple of the counter weights. and got a print out of all the weight and reciprocating factors. He stated that would be good for what I was doing running the streets. Ths is better than doing nothing I would think!
Not even close in my world
As soon as you change parts in an engine there is no such thing as a so called "Detroit balance"
GM has specs they use for FACTORY PARTS
Now even though the tolerances are very loose by performance standards they do have a tolerance
What do you suppose happens when you install aftermarket parts that are not somewhere near the original weights?
And what is the point in calling something balanced if you do not check & match all the parts not just one
I am sorry but to me this should not even be called balanced
I do not care if you buy a $300 crank or a $3000+ billet from me
If I am balancing your rotating assembly the same rules apply or I don't do it.
As for internal or external
If at all possible I balance everything internally.
While there are many engines out there externally balanced that appear quite happy if you understand balancing you will understand that the closer you balance to the point of unbalance the happier the part will be
If you do not believe this take your trick shiny wheel & static balance it by adding weight to the inside when it wants weight to the outside
On a static balancer it is fine
Now stick it on your car & go drive the thing & tell us what happens,,,
This is only 8 inches or so from the point of imbalance
What do you suppose a crank does when you hang the weight off the end
You may not feel it but your bearings can