yep, probably the air leakage around the shafts plus the slop in the shafts
allowing them to stop moving when not all the way closed at the butterfly.
Shaft and bushing rebuild time.
Don Marshall wrote:
> I need some help diagnosing a sticking throttle problem I'm having with the
> TR4 (full race, radical cam, etc. if that has any affect on the diagnosis)
> It runs fine, but when the throttle is released, about half the time the
> revs will only drop to about 2500 and stick there until I press the linkage
> at the carb to force it closed. The rest of the time it drops all the way
> to idle without any problem.
> I've disconnected the linkage completely and the springs on the shafts are
> adjusted tightly to pull the butterflies closed. The carb pistons are free
> and drop with a good thunk so I don't think they're sticking open. I
> haven't had the carbs apart to adjust the butterflies yet. There's a fair
> amount of movement at the shaft, so it might be sucking air.. could that
> cause it? Anywhere else to look?
> Thanks from sunny Florida, where some of us only get to vote once, dammit.