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You can rig up a manometer to compare the vacuum with a length of clear plastic tube - maybe about 1.5 metres (4 or 5 feet) would be enough. Put some kerosene (no worries if it gets into the engine) in the pipe, and let it settle in the centre sag of the pipe to give maybe 6" each side of the mid-point (amount isn't very critical, but put an elastic band around the U-tube part to keep the arms close together). Remove the air cleaner and tape the ends to the air-cleaner support screws, symmetrically in each carb, pointing down. The movement of the kerosene surface in each arm shows the amount of imbalance in the carb vacuums. It's very easy to see if they are balanced at speed too, but as you say, it isn't very critical due to the balance-pipe(s). Well-balanced carbs are really nice to drive with though. I disagree that the mixture screws are used to adjust the idle speed. The VW method is to turn them in until the engine begins running unevenly, then undo about 1/4 to 1/2 turn until it is smooth again. Later info mentions using a CO meter to check this. The idle (throttle-stop) screws are used to set the rpm and the balance (then the right-hand adjustable connecting rod is matched to the distance between the spigots so it does not disturb the setting). If you have a spare air-cleaner assembly, you can solder a small spigot in the air-cleaner over each carb and attach the manometer device, then adjust with the engine under normal operating conditions for an even more reassuring result. I inherited such a device from a PO - much better than inheriting problems! Dave. UK VW Type 3 & 4 Club http://www.hallvw.clara.co.uk/ ------ ------------------------------------------------------------------- Search old messages on the Web! Visit http://www.vwtype3.org/list/