New shortblock got balanced with a flexplate, i might go manual now, so will the weight difference between the flexplate and flywheel make a difference.?

 

If you are building a new motor, the smart choice is to have it internally balanced to neutral and then you will have no potential problems when changing flywheels/flexplates, etc. However, in theory, if the new rotating assy. is balanced against a flexplate with the stock counterweight, a manual tranny flywheel with the same balance SHOULD work.

Rich

 

Take your old flexplate and the new flywheel into a machine shop and have them spin them to verify balance. Might as well take in the clutch and pressure plate as well and have the whole assy matched up.

 

If it's an externally balanced engine then it needed the flexplate for balancing. Changing to an externally balanced flywheel, may throw off the balance.

If the engine is internally balanced, then they didn't use the flexplate when it was balanced. It won't matter what neutral balanced flexplate/flywheel you use. If both are neutral balanced, the heavier flywheel won't change the engine balance. It just adds inertia. Spin a light wheel and it stops quickly. Spin a heavy wheel and it takes longer to stop because of inertia.

I had my new engine balanced this year. The new BBC crank is internally balanced. I needed to buy a new neutrally balanced balancer and flexplate but didn't need to give them to the machine shop.