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Weber Carbs

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10musketeer

10musketeer

Jedi Trainee
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I'm reinstalling a Weber on a 1275 and am having trouble wrapping my mind around something that I'm sure you guys can help me with. I hope I can explain it!

If I hold the accelerator pedal to the floor the carb is only opening about 2/3 of the way through it's travel. The crux of the issue is how do I adjust the carb to close all the way when the cable is slacked and open fully when the cable is fully tight (pedal to the floor)? If the cable moves two inches of travel, then how can I increase the amount that the butterfly will rotate? Is the adjusting in the carbs throttle plate or maybe the pedal itself?

I'm sure it's simple, but I need to take a break and thought I would tap into your expert advice.
 
Not having it to look at is a bit of a disadvantage, but: pedal travel seems the culprit at first guess. There should be an adjuster (simple bolt and nut) for the return limit on the pedal and a WOT stop. Both need to be taken into account so as not to bend linkage and shaft bits, yet still allow full shaft rotation. I'll guess this is a DGV or derivation thereof... is there a "wheel" or a lever on the shaft at the carb?

With two inches of cable movement I would think you'd have "left over" movement, not 2/3 rotation. Is the cable fully "home" in the actuating rod of the pedal at fully closed?

...just tossin' out some thoughts.

Can you post a couple photos of the "business ends" of the linkage?
 
Hello John,

if the throttle pedal has full travel, then to increase the amount the carburettor butterfly opens you need a shorter radius on the wheel or lever that is attached to the butterfly spindle. If you need 50% more rotation (2\3 divide by 1\3) then the radius of the lever or wheel needs to be reduced by 1\3rd. Just be sure that at the half way open point that the cable to lever angle is 90 degrees. (or if it's a wheel then that is not relevant as long as you have enough wrap of the cable. You lose a lot of mechanical advantage if the angle I mentioned is significantly more than 90 degrees at the half way point.

Alec
 
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