Changing Flywheels and Engine Balance

[lizziemeister'sV6]

Curious on how GMC V6 owners change their flywheels and still keep their rotating mass balanced? I have had my 351 V6's in the engine rebuilders shop in the years pass and they always required the flywheel to be mounted at the time of rebuild /balance - they are different flywheels for the Powerglide and Turbo Hydramatic as well as the clutch flywheel. I'm planning on changing my Powerglide to the 3 speed Turbo 400. Whats your thoughts?

[bigblockv6]

305,351 & 401 V6 engines are internally balanced so flywheels for these engines are zero balance. Swapping compatible flywheels on these engines isn't an issue provided engines still have the factory balance on them. Engine builders do balance the whole rotating assembly together on just about any engines and if they do add or remove any weight on the flywheel then that flywheel will throw the engine out of balance if it's put on another engine. 379, 432 and 478 V6 engines are externally balanced so there is weight added to the flywheel as well as the front balancer. In my 478M conversion I had a custom flywheel, when the engine was balanced a good amount of weight was welded to the flywheel as well as the front pulley.

[Mulana]

Does any one know if the 379, 432 & 478 flywheels are the same or is each one balanced differently?

[lizziemeister'sV6]

Each one is machined/balanced different according to the engine they was installed on. There for you cannot change flywheels on these engines. Read previous thread by BBV6 for full reasoning. Good luck with your engine -