My balance specs ?

It all depends on the machine. (not the machinist, he can only be as good as the equipment) Where I go, has an up-to-date computerized balancer set up. Its an option on the Rottler. They can get within .5 gram, and many shops arounf here cant get closer than 6g. I've seen them rebalance a previous shop's work on circle track engines (that really NEED to be right) because the equipment used cant get the accuracy. Think of a bubble balance for tires, vs a spin-balancer...Bubble is better than nothing, but cant get that accurate. I agree with BJR..internal competition balancing is all my engines get. The extra hundred or so it may cost is worth it to me, and it's way to pricey to re-do after the fact.