[Zak]

Is there anybody that has dropped in a crank into a motor without balancing it, and what was the result?

The reason I'm asking this question is that I have a 347 Eagle crank with 3.4" stroke installed already but yet I haven't balanced it. Only the bottom end is assembled so it's not too late to dismantle it again for a balance job.

I have another 331 SCAT crank with 3.25" stroke that has been balanced with a .28oz harmonic damper & a flywheel, but the rods & pistons were not used in the balance job at that time. I'm sure of that.

I came across this article and it just woke me up:

Muscle Car Magazine: Balancing

Thanks for your advices.

[fogged306]

I've been told by everyone I know to balance the crank before you put it in. I dont know from experience but these guys have raced everything under the sun and I trust them. Im actually taking my crank to get balanced at the end of the month, its the only thing stopping me from assembling my motor but I've been told it will be worth the wait. I also heard the motor will rev a little quicker with a balanced rotating assembly but im not sure how true that is.

[Zak]

Originally Posted by fogged306 I also heard the motor will rev a little quicker with a balanced rotating assembly but im not sure how true that is.

I would believe that because there will be less stress on the bearings when the crank is properly balanced. Looks like I have to do a rework but as you mentioned, it is worth it.

[1slo5.0]

Balance the entire rotating assembly, not just the crank. This will make the bearings and parts live longer and reduce or eliminate vibration. You'll probably gain a few horsepower in the process as well. I don't put any engine together without having the rotating assembly balanced. Doing it any other way is just a half ass hack job. Balancing is cheap.

[fogged306]

Sorry to hijack the post but does anyone know roughly the cost of having the entire rotating assembly balanced?

[1slo5.0]

Usually a couple hundred dollars.

[86er]

150 out here in bama, glen sheppard, use to build the allison brothers nascar motors,

[Clockman]

Originally Posted by Darrell Balance the entire rotating assembly, not just the crank. This will make the bearings and parts live longer and reduce or eliminate vibration. You'll probably gain a few horsepower in the process as well. I don't put any engine together without having the rotating assembly balanced. Doing it any other way is just a half ass hack job. Balancing is cheap.

dumb question how do they balance the entire rotating assembly is it in the block with pistons? being balanced?

[1slo5.0]

Originally Posted by Clockman dumb question how do they balance the entire rotating assembly is it in the block with pistons? being balanced?

Not in the block. Good machine shops have equipment to weigh and balance everything.

[jam77]

they have fixtures that attach to the rod journals that are filled with lead shot that are the exact weight of your pistons and rods. Than the crank and fixtures are put on a machine that pick up the slightest movement then the machinist will either add weight to the crank or take weight by drilling the crank. my dad owned an automotive machine shop for 24 years