I can't tell from your question if you put each gauge on a carb and were actually syncing, or if you fed all four to one carb and were calibrating the tools. If syncing, what happened when you used the adjuster to alter the pair of carbs that included the one low-reading carb? If calibrating, what happened when you turned the low gauge's calibrating screw?
The guages in the link appear to be the ones that everyone is saying have calibration screws and at the same time are the lowest cost ones avaialable.
sorry..I was posting caffeine deficient. lol
we had them hooked up to the carbs and if we adjusted them it remained approx the same compared to the gauge for the other carb.
I didn't think about nor test the gauges in regards to calibrating them. I need to do my 82 so I will check the gauges against each other before hand.