How to balance left and right bank idle?

Close both air bleeds, connect vacuum gunge to both banks, with correct fuel mixture adjusted with an exhaust analyzer set the throttle stop screws so it idles at 700 rpm with the same vacuum readings on each bank. Using the air bleeds raise idle to 1000 rpm with correct fuel mixture and even vacuum. The mixture needs to be observed and corrected during the procedure. At low engine speeds small speed corrections cause big changes in the mixture.
Then reconnect throttle linkage and be sure it operates both banks in harmony .

 

Its been a while but as I recall its really the only suitable one. It needs to be below the throttle plate.

 

If you use two gages, be sure they calibrate to the same number; these gages are accurate to see change but not necessarily exact vacuum. You can use a hand pump with the two gages on a T to see if they read the same. Instead, I bought a Dwyer differential gage and zero is adjustable if needed.
Ken

 

Also make sure you use a T-junction, otherwise you'll take the WUR out of the equation.

Esben