My unisyn is about 40 years old now and its GREAT. I think you can get them for under $50.00 and they last forever. Well, they last at least 40 years!
I've used them on a lot of different multiple carb setups. Webers DCOEs, Su, Stromberg, Hitachis, and even a couple I could not identify!
Side draft, downdraft, 2 or 3, you just have to be methodical and keep adjusting the angle to keep the bubble vertical and the inner plate to keep it fairly centered. Don't adjust those between checking cylinders though. Here's a rough methodolgy...
First adjust timing, valves and anything NON carb. Then check between the carbs and see how they compare. Use a piece of tape as a reference if you need it. If the idle is smooth and they are all within a half bubble or so, I would not go any further. If you have a searching or rough idle, the fun is about to begin. First get the highest reading out of each carb by adjusting the idle screw. This is actually best done with a CO or four gas analyzer, as the unisyn will cause you to go a tad rich. However, if you don't own a unisyn already, you probably don't have one of these either!
Repeat on each carb and check to see if they are within the bubble. If not, the next step is to adjust the idle speed screws to match. Don't forget to check that you are within your factory specs on idle speed! Listen carefully for any surging, searching or roughness. Repeat the process to your satisfaction. At this point, if I am using just the unisyn, I would give a eighth or quarter turn in on all the idle mixture screws. I would then run the engine a bit and recheck once more. Have fun.
