hey all! how can i tell if my carbs are running rich? i have a 72 240Z and had it started up for a guy the other day, after messing with it for a few minutes he informs me that it is running way rich. how do i check this? how do i change this? also what are the chances of me having engine damage from thinning out my oil? i have only run the engine like 4 hours total so far.