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Re: [T3] dual vac distributor [was distributor 009]


On 13 Feb 2005 at 18:46, Dave Hall wrote:

> I assumed the different diameter of the pipes would make for a gentler
> transition between the fully retarded, throttle closed state and the throttle
> open position as air flows in or out of the two chambers - like a dashpot.
> It's quite a large diameter diaphragm in those.  They must be different specs
> for a reason, unless the diameter info is actually erroneous?
> 
> Yes, I have an example of each - I can take a look to see if the bore is
> different, and will have to get out the timing light and do some measurements to
> see what happens in each case.

I think the advance port is a molded plastic part so it has a thick wall and a 
smaller center hole. The retard cavity has a thin walled steel port so it has a 
larger bore. Maybe there really is a reason for this, but I doubt it. I've seen 
the same part # of advance can with a steel port on the early ones and the 
plastic one on the late ones.

Besides, the drillings at the carb (or intake air distributor) end are much 
smaller than either of these, and I suspect that dominates the time constant.

My guess is that someone at the Scientific Publications end of things was just 
guessing.

-- 
*******************************
Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA
*******************************

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