Is a 70 440 HP internally or externally ballanced?

[troy.70R/T]

Here is my guestion. I have a 1970 440 HP 4 barrel with forged crank. was going to hook it up to a 1968 11 inch bellhousing and 11 inch flywheel.  is an 11 inch fly wheel ballanced? Was the 70 440 HP motor internally or externally ballanced? If the flywheel is not ballanced how can I tell? weights welded on it, or holes drilled in it? If the motor is internally balanced would there be a problem if the flywheel is also balanced? just want to get this stuff figured out before I try to start it.  Any advice or web sites that you could direct me to would appreciated. Thanks Troy

[supserdave]

Do you know which rods you have?

[troy.70R/T]

I belive they are forgred six pak rods I know they were individually ballanced when I had the motor rebuilt

[John_Kunkel]

All '70 440 HP's had the heavy rods and were externally balanced.

The attached pic (top) shows how to imbalance a neutral balanced flywheel.

[troy.70R/T]

Thanks for the info. however I must admit I feel stupid This really does not clarify my guestion.  Is my 11" flywheel balanced or not if it is balanced does that mean it will be fine to put on a balanced motor. or does a balanced flywheel unbalance a balanced motor? Sorry for not knowing what your telling me I just don't want to start the motor untill I KNOW I have tis fully understood. Thanks Troy

[firefighter3931]

The 68 flywheel will be a neutral balance piece. If your 440 is externally balanced you will need to modify the 68 flywheel as shown above or get a flywheel for the application. 

Just because the rods were staticly balanced does not mean that your engine is now internally balanced....just so that you're clear on that. 

From what i've seen, the stock "external" balance flywheels will have a small "scallop" cut out the ring weight. There are also several manufacturers that make external balance flywheels that are SFI rated.



Ron

[idahogrumpy]

  If the engine was rebuilt by someone who knew their stuff the engine could be internally balanced. If you know the engine was balanced when the rebuild was performed and you are using the same harmonic balancer and nothing internally on the engine has changed the flywheel you want to use should be just fine. (Talk to the engine builder) The 1969 flywheel should be of neutral balance. If the engine was assembled or rebuilt as it was from the factory then the offset balanced flywheel that John spoke about will have to be used. The six pack flywheel will also require the use of the newer 70 & up bell housing and the 10 1/2 or 11" scalloped clutch because the 70 & up flywheels were 10 1/2 ".  I believe the after market scattershields have patterns drilled in them for the 10 1/2" or 11" flywheels. (starter location)
   If the history of the engine is not known it would be safer to tear it down, re balance it with the components you plan to use and go on with life. 
Good luck    Grumpy