I am still working on a complete downdraft Weber linkage system and slowly making progress. I am confused about the instructions given on the forum and in the workshop manual about synchronizing the downdraft carbs. Both versions suggests that synchronization should be done by adjusting the idle speed screws on each carb with the adjustable linkage rods disconnected and then matching the length of the adjustable linkage rods to line up with the balls on the carb levers to set synchronization.
That would work but it seems the same thing could be accomplished with fewer steps by using the same method used on side draft carbs, i.e., with the adjustable linkage rods disconnected, set the idle speed screw to about 1/2 turn in on both carbs. This is the baseline. Reconnected the linkage and adjust the balance lever on carb #2 to match the air flow on #1. Since the front carb lever can't move, the adjustment opens the butterflies on the rear carb for synchronization.
The same could be done on the downdrafts by setting the idle speed screws to baseline, reconnecting the adjustable rods adjusted to the baseline length and then, with the OEM adjustable linkage rod on the rear carb, doing the sychronization. That way there is no need to try to match the length of the rear adjustable rod to the position of the carb lever by removing it, changing the lenght, reconnecting it and repeating the process until the correct lenght is obtained. It seems to me that that OEM knurled knob rod is designed to do just this job without the disconnecting and reconnecting. Am I missing something here?
That would work but it seems the same thing could be accomplished with fewer steps by using the same method used on side draft carbs, i.e., with the adjustable linkage rods disconnected, set the idle speed screw to about 1/2 turn in on both carbs. This is the baseline. Reconnected the linkage and adjust the balance lever on carb #2 to match the air flow on #1. Since the front carb lever can't move, the adjustment opens the butterflies on the rear carb for synchronization.
The same could be done on the downdrafts by setting the idle speed screws to baseline, reconnecting the adjustable rods adjusted to the baseline length and then, with the OEM adjustable linkage rod on the rear carb, doing the sychronization. That way there is no need to try to match the length of the rear adjustable rod to the position of the carb lever by removing it, changing the lenght, reconnecting it and repeating the process until the correct lenght is obtained. It seems to me that that OEM knurled knob rod is designed to do just this job without the disconnecting and reconnecting. Am I missing something here?
