Last job is to balance the carbs, and I can't seem to get it right

[Disorderlypunk]

im with daviee on this one
if there is a stopper to say zero (1bar) then i would avoid buying them, i would prefer something that does both negative and positive pressure.
when calibrating at home i would use one carb as a control to see they are all giving the same reading (calibrated to each other)
these setups are not that good at giving correct pressure readings but they can be good for making sure they all have the same negative pressure.
if you want accurate pressure readings from 4 individual carbs then the 30 quid kits are not going to cut it.

i will say i dont have one of these relatively cheap set ups myself but have come across them now and again - they can be usefull as long as they are calibrated now and again.