You need to pick up a carb sync manometer...(Easy to build one on the cheap)...
The biggest issue with multiple carbs is making sure the linkage is dead on balls accurate...
The vacuum signal at the base of the carbs needs to be identical from #1 to #3....The vacuum signal is the best way to dial them in IMHO...
First set up the idle circuit, this is typically where the most noticeable problem is, it can cause lean popping, hesitation and sputtering, not to mention a rough ass idle...
You can use what's called a slack tube manometer, but it will need to be about 20' tall if you are going to use water for a measurement fluid because there are 13.5951001967 " of water in just one inch of mercury (hg)...This engine will idle at about 19-21"hg...
I recommend finding a digital vacuum gauge and using that to balance the idle....
Once the vacuum readings are equal at idle, only then can you accurately adjust out the fuel circuits to gain proper fuel mixture at idle..
After this stage of the game, the engine should run like a Swiss watch, the rest is tuning the accelerator adjustments and high speed jetting...
Good luck...BTW I have done literally hundreds of these, Blue Flame 6's, Tri Power, Six Packs and Strombergs, not to mention multiple carbureted outboards....
The hardest one I ever did was a Force outboard....Five cylinders and 3 carburetors....Do the math.
GT
