Randy - since the butterflies in the DCOEs are permanently fixed to each other, could you explain why it's necessary to check both sides of each carb, rather than one side only? Why are the columns slightly different within each carb?
Enquiring minds want to know! :fat:
PS - with the manometer, you can easily check your balance without removing the air cleaners!! That's a strong feature right there!
The different readings are because the exposure__the time the "shutter" captures the moment__is
thousandths of a second frozen in time, and the cylinders are constantly "pulsing" at different times, depending on their intake stroke. To the naked eye, the readings are balanced (averaged, because we're__at least I'm not__fast enough to focus mid-pulse).
While the pairs of throttle plates are fixed to the same shaft__two (2) venturis per carb__that's no guarantee that the airflow is the same. There is a compensation air adjustment on each barrel (2 per carb) and one side will always read higher/lower vacuum than the other when both compensation needles are completely closed. The side with the lowest reading is kept closed, while its mate is opened up to match it.
The following text and diagram was taken from the Weber's
factory service manual; the example used is for two (2) carbs, but balancing three (3), four (4) or six (6) would follow the same procedure:
You'd be shocked at the number of people getting paid to "tune" Webers that have never heard of this, or think that those screws are for
emissions, or some other such thing not applicable to "racing" carbs!
Once you have the individual carb barrels balanced, THEN you can balance and set the idle speed and tighten the linkages together, similar to how you'd do a pair or trio of SUs.