Yes, the MK IV models had a somewhat unusual "vacuum
retard" system.  There was vacuum only at idle.  The
point was to retard the timing at idle for emissions
reduction.  Any time your foot was on the gas, there
was effectively no vacuum control of the timing.

If you have this type of carb, and you connect the
vacuum port to a distributor with a normal vacuum
advance, it will cause only trouble.

Doug

--- Luke Lewis <[EMAIL PROTECTED]> wrote:

> Check where the port is open to.  If it's open to
> the inside of the 
> butterfly, it has max vacuum at idle.  If the
> butterfly passes it as it 
> opens, it doesn't get vacuum until you're under
> load.
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