stage, welcome! i see you're from gainesville. i try to make it up there every saturday to the dragstrip. anyway, i dont want to be the bearer of bad news, but from what i can remember about smoke colors and conditions, white usually means piston rings. are you sure it did'nt have a blue tint to it? what kind of knocking was it? was it a tick-tick-tick or the like the sound of rod hitting the cylinder wall? anyways, a new set of rings for a ls1 dont cost much to do yourself, but if you take it to the shop, it can be some serious $$$.