I picked up my rebuilt engine today, 427 stroked to a 496. New crank, rods, pistons, cam, roller rockers push rods and valves. My "old" engine was externally balanced, my "new engine" is internally balanced. The builder said do not use the old fly wheel. Question: Do I run an off the shelf Fly wheel or do I have to have this balanced also?? I'm not a mechanic, and I don't even know if there is such a thing as balancing a fly wheel. I'm confused I know someone on this board can help. Thanks!!!
Bob G

buy flywheel for internally balanced engine; your externally balanced flywheel will not work....or a good machine shop can balance your flywheel to specs of internal blanced engine

All you need is to have it neutral balanced. Any shop with a engine balancer can do it. My motor is internally balanced. I use the stock flywheel and I balanced it. I worked for an engine builder and did it all the time.

Bob, I just built 2 engines similar to yours. I used this flywheel on both of them. The internal balance is an advantage over the stock external balance.

This is the best flywheel for the money in my opinion. Comes already neutral balance and SFI certified
http://www.racepartsoutlet.com/PartDetail.cfm/ID/39976

Baja, I'll order that on Monday! Thanks evryone!

Are you sure you want a light weight flywheel.
I know it will rev quicker but do you really want that on a boat?

So I took two 454 blocks, had Eagle rotating assemblies installaed and balanced with the stock flywheels on. Apparently, the flywheels are now specific to each engine and i was told to be sure not to mix em up, although it doesn't matter which way is up. I'm not an expert, so I just took it all in but do you know why this would matter with internally balanced rotating assenblies?

If done right it shouldn't matter with internally balanced motors. Depending how close they got the rotating assembly without the flywheel. Normaly you would balance the crank with bob weights(weight of piston , bearings, rings, rotating and recipacating weight of rod and oil) within a gram or less. Then you put the flywheel on and balance it or balance it seperate on a mandral to a gram or less. Some guys will get the crank so close and then finish it up with the flywheel which is not the right way. If done right you would be able to switch flywheels. Same with the harmonic balancer. Hope this hepls. My typing isn't that great.