Since this was not touched on again Ill take another shot. The timing is about initiation of air\flow into the ventures' which starts the fuel flowing out of the boosters. My theory is by making it tighter (or slower acting with restrictors like Doc F) you are allowing the engine speed to come up more before the air door flops open creating the lean spot or possible over rich spot (??). Where as if you set it up like the factor with .1 to .3 of clearance the door is allowing air to begin flowing which pulls the door open immediately (kinda like a door in the house that is shut wont let air through, but if the door is cracked open a little and another door opens somewhere else in the house the pressure drop and air flow through the house either slams/flings open the door)