[mr70chevelleman]

Hi, I have a BBC 454 in my 70 Chevelle and I need a new flexplate, the engine has been balanced and blueprinted and Im not sure which flexplate to choose, they make an internal balance and an external balance, just wondering which one i should be using?

 

[Stripey]

A stock 454 is externally balanced so thats prob what u need.....unless u spend the money to make it an internally balanced motor. If it was just a standard procedure balance job...u need externally balanced

 

[Schurkey]

Does the old flexplate have a weight welded to it? If it does, and it looks "factory", you need an external-balance flexplate. If it does not, and it looks "factory", you need an internal (neutral balance) flexplate.

If it has some kind of weight--or drilled holes to lighten it--and it looks like it was done after the flexplate was made, you need to haul the old flexplate and the new one to a balance shop to have them matched. Balance shops that rework the damper or flexplate are doing a poor job--but it does happen.