I took my '62 Chevy II for a test drive right after putting the motor in without the airfilter on it, but the 1/4 nut was on the shaft, after I got back the nut was gone. So I pulled the carb, and looked for it and couldn't find it. Someone told me it must have just pass thru, so I rev it a few times, and Bang, I cracked a piston! That was on a 327 with a mild cam. I wish I had your luck with it!

Pat