Does Crank Stroke Affect External Balance

[toolmanmike]

Go ahead and build your stroker and externally balance it with components for a different combination.

 

[72DMag]

@pishta I guess you might have nailed it then!! the article and author states to not add mallory to save on the balance bill but after re-reading it you are right he says it reduces the balance bill not that it doesn't need balanced at all!!

So My next question is what would it cost for shop to balance rotating assembly say for this case where we know the metal will need taken off of the crank?? I'm assuming there would have to be some charge since they still put it on the machine and spin crank with rod and piston etc...

 

[pishta]

I got a quote for $75, no mallory if I hand him 1 balanced rod assembly with the piston pack not mounted. That way he could weigh the rod big end, and the piston pack. This was only for the crank balance, nothing more. I balanced all the other stuff to itself and the balancer was already neutral so everything was the same for his bobweight. My crank had a factory bobweight target of 2050g and my stuff measured on my jerry-rig was about 2020g so I should come in under weight. IIRC you can't balance a fluid type damper so Ill just run with the factory neutral balance of it.

 

[Mopar Sam]

I got a quote for $75, no mallory if I hand him 1 balanced rod assembly with the piston pack not mounted. That way he could weigh the rod big end, and the piston pack. This was only for the crank balance, nothing more. I balanced all the other stuff to itself and the balancer was already neutral so everything was the same for his bobweight. My crank had a factory bobweight target of 2050g and my stuff measured on my jerry-rig was about 2020g so I should come in under weight. IIRC you can't balance a fluid type damper so Ill just run with the factory neutral balance of it.

That is cheap. I get twice that for doing single cyl Kohlers, and more if they need tungsten.

 

[Wyrmrider]

if you figure the stock balance factors and then source your new build with less weight you can balance without heavy metal
stroke does not matter doing it that way
you need lighter pistons/ pins/ rods with the longer stroke
using a longer rod/ shorter lighter piston works (maybe a piston for an evev longer stroke with rods to match)
most cast cranks are going to be extenal balanced- not a problem at stroker rpms

 

[pishta]

The rod doesnt get longer, its the same rod but a shorter piston so the piston is always lighter than what its replacing, the big end is more important weight wise. but it all adds up