1. Tom Endy's web site,specifies the following flow rates using a 36 inch column of water.
http://www.ocmafc.com/techarticles/Tom%20Endy%27s%20Special%20Topics/Newer%20-%2001-2010/Zenith%20Carburetor%20Overhaul%20-%2011-2007.pdf
Flow test values (jets):
Main – 140-150 cc per min.
Cap – 150 – 180 cc per min.
Comp – 138 – 142 cc per min
Idle – 38 – 42 cc per min
2. Steve Pargeter's Zenith Model A Carburetor Restoration Guidelines version 3 specifies the following flow rates with a 36 inch column of water.
Flow test values (jets):
Main – 150-160 cc per min.
Cap – 150 – 185 cc per min.
Comp – 138 – 142 cc per min
Idle – 44 – 48 cc per min
3. Gordon Biggar's Restoring the Model "A" & "B" Carburetors the "Rex" Reheis way specifies the following flow rates for the A carburetor
Carburetor Flow test values (jets): at 36 inch column of water Model A
Main – 140 - 150 cc per min.
Cap – 150 – 185 cc per min.
Comp – 138 – 142 cc per min
Idle – 44 – 48 cc per min
4. Gordon Biggar's Restoring the Model "A" & "B" Carburetors the "Rex" Reheis way specifies the following flow rates for the B carburetor
Carburetor Flow test values (jets): at 36 inch column of water Model B
Main – 136 - 142c c per min.
Cap – 372 – 462 cc per min.
Comp – 110 - 118 cc per min
Idle – 43 – 47 cc per min
Power 110 - 118 cc per min
Carburetor Flow test values (jets): at 37.25 inch column of water Model B
Main – 138 - 144 cc per min.
Cap – 378 - 470 - 185 cc per min.
Comp – 112 – 120 cc per min
Idle – 44 – 48 cc per min
Power 112 - 120 cc per min
TC, I hope this helps. There are a lot of different flow rates recommended, In Gordon Biggars book they state the ranges were developed by Steve Pargeter, so you may assume that that the main jet flow data in paragraph 3 above (140 - 150) is a typo and should be 150 - 160??