does anyone know what the difference is gram wise between a street balance & race balance.i know that some shops may vary.

I don't thing it's an actual weight issue as much as it has to do with tolerences allowed.

I have seen and heard of as much as 18 grams differences in stock pistons and rods, most good balance shops shoot for one gram variences on rods(with bearings and oil), pistons (with wrist pins and rings) on there balance jobs. Some achieve that and some don't I have a Haus triple beam balance scale so I do check the parts now and then just to keep the shops on thier toes BTW, to do balance checking properly you need a shadow graph and a crankshaft balancing machine, which I don't have

ok i was a little vague.i was more interested in tolerances in grams.i have done my 440s & a few small chevys at a friends shop.i've always tried to keep pistons/pins & rods within 2 grams & crank within 5 grams on street/strip engines.

Cab i had a set of LY rods that varied 14 grams on the big end.

Matching the weights is the high school stuff.
Knowing where to remove the weight from the crank is a whole different game.

race balance will likely over balance +/- 0.5-1%