>... the real 
> culprit is not getting enough quick spark advance (provided by the vac advance 
> distributor).
> 
> I don't know which bus you have, but this may help you out with your decision 
> on which distributor to use.  The 009's are readily available, anywhere from 
> VW shops to mail order (including JC Whitney).  But I like the idea of having 
> both vacuum and centrifugal advance - a good compromise.

As I understand it, the popularity of the 009 is because when you put 
on different carbureters, Delsnortos or Wubbers, you lose the vacuum 
port in the carbureter. The stock distributer then won't provide 
sufficient spark advance range (~28 degrees?) for proper engine 
running. However, the 009, especially if advanced too much to begin 
with, can't sense when you have a lean, hard to ignite mixture that 
needs to be compressed more by the piston before it can burn. The 
vacuum "advance" actually retards the spark when the vacuum drops to 
a low value, i.e., when you stomp on the accelerator. 

Your 3PICT-3 carbureter probably also has its vacuum port positioned 
so that the vacuum is cut off at idle. This retards the spark so that 
the combustion is more consistent at idle, producing fewer unburned 
hydrocarbons so you can "pass the gas" test. 8^p

Rich.

Richard Lamoreaux   Tucson, AZ
lumpy@rtd.com       (602)296-1226

'78 Chicken Coop
'87 Weekender