I've checked my floats a couple times, but never with the car running. I didn't feel like I wanted fuel dumping on the manifold. I had the fuel set just so it was weaping out of the hole, (basically level with the bottom of the hole).
I have always adjusted the floats running,, you can put a cloth under the carb to catch any spillage.. You could simply be running outta fuel cuz of low float level.. ?? .. jmo
