The method for bench syncing the carbs has previously been to use a wire or needle as a feeler gauge between the throttle plate and carb body. But, when Mike Nixon, noted GL Carb Guru joined this board he brought to my attention that the wire/needle method can cause "nicking of the throttle plate which permanently ruins the plate and introduces unregulated air." And you know that he's seen the guts of enough of these carbs to know what he's talking about.
So, how to get a decent bench sync?
Simply look into and around the outlet port of #3 carb and locate the bypass outlet. It will be right along the line of the resting butterfly.
Note the relationship of the outlet to the edge of the butterfly. Now, adjust the 1/3 sync screw so that #1's butterfly position matches #3.
Flip 'round to the other side and adjust #2 and #4 so they match each other. The 2/4 sync screw is between those two carbs.
Lastly, adjust the left bank's sync screw so the 2/4 set matches up to #3. The side-to-side sync screw is aft of #4 carb.
Thanks to Mike Nixon for the info and pic!
You do not have the required permissions to view the files attached to this post.