A note or two...If you replace pistons with oversize stock replacements, the new pistons are heavier. That is called "underbalanced" and can lead to all kinds of issues. Many guys dont balance. I suppose if all 8 are the smae extra weight, it will limitm the amount of out of balance..but the pistons are not teh main offsetting force. The crank counterweights (and harmonic dampener and torque convertor weights on cast cranks) are what offsets the pistons and small ends of the rods. It is less of a probelm if the crank is heavier. A situation called "overbalanced". Some race engines are overbalanced on purpose. For engines I build, I internally balanceall of them. For a bunch of reasons. First, I replace dampeneres. So a neutral one goes on. Second, it means any flywheel or flexplate and/or torque convertor can be installed at any point, with no concerns of whether or not it will vibrate. Third, it it the best way to keep vibratiosn to a minimum. That means more power for a longer life, plus less stress on internal parts while producing that power. The only down side is the cost. The cost to balance always includes the same work. For every balance job, the weights of the big and small ends of the rods, plus the pistons and pins must be equalized. Then the actual weights of the parts are added to the crank. The last step is to spin balance the crank with those weights on it and either add material or remove material to get the crank "in balance. The dampener and flywheel or flex plate and/or convertor are left off when an engine is internally balanced. If you bolt them on, you use thier wieght to help get the crank in. Those parts are "outside the block". Hence the name external balancing. I dont want those to be a factor, because most dampeners(harmonic "balancers") and performance torqconvertors are neutral balance unless you make them otherwise. If you include yours in the spinning process, you mandate the use of those parts indefinately with that engine. On a 360, you can buy a B&M flexplate for about $80 to be able to use neutral torque convertors. But if you have to spend $100 on Mallory (heavier tha iron or steel) metal, you can say that the bonuses of power and longevity will cost you $20-30 more. Is it worth it? It is to me. Also, reusing a balancer on a high performance engine can lead to interesting things like slipping outer rings and engine damage due to lost efficiency from aging elastomers. Frankley, IMO, it's not worth saving $100 by re-using them. You may be able to save some $$ by using a grams scale to match the weights yourself. I can save $50 on the $300 cost by doing that myself. but the shop will stil need to weight the ends seperately unless you buy the stand to do it.
