I would just like to put out there an interesting observation regarding engine balancing and these people who worry about 1 or 2 grams. A freind of mine runs a 340 in a form of circut racing where the engine is run up and down through the gears to a redline of 7500 for a period of about 50 minutes per race ( theese motors are worked hard)
After an engine faliure the crank and two rods were taken out so a new crank and two replacment Carilos were installed, the rotating assembly went off to the balance shop. The new assembly was installed and raced for several meetings without issue. On the next teardown some new pistons went in and the engine was rebalanced at a differnt machine shop. It was at this point it was discoverd that the two new rods that had gone in on the previous rebuild were 31 grams heavier each than the other six. It turned out the previous machine shop had all the weights in there computor when they balnced the motor the second time and had not bothered to check the weight of the two replacment rods so that was a total of 62 grams on the same rod journel and the motor run hard with no noticable vibration or issues. This was not ideal but makes me wonder how critical 1 or 2 grams is in a balance job!