been reading your thread with great interest, as i've recently installed a set of su's on my 78 280. i set float levels on the bench running the fuel pump into shot glass bowls, then re-set them on the car with a sight glass but i was still lean on both carbs, significantly more at the rear carb. this site: http://www.zcarz.us/technicalinformationpagecarburation.htm had some good info re setting fuel level at the nozzle vs. focusing solely on the float bowl - makes sense since the the fuel actually draws from the nozzle. his measurement shows 1 cm down from top of the bridge, so 10 turns down and the fuel should be right at the top of the nozzle. remove domes & pistons and look straight down and you can see it. i would keep it at 8 turns down, adjust the float, run the pump to fill the bowl, then dial in the last 2 turns to see if i had it. when it's right, the meniscus should hit the top of the nozzle at 9 turns and the fuel just flows over the top at 10 turns. this method worked for me and when i was done the float bowl levels, measured with the sight glass, were pretty different (both higher than 23mm, the rear quite a bit more than the front) but the nozzles were dead on and it runs well in the 2-3 turns down range.