Hello list,

I am trying to understand the various mechanisms that
control the timing on the early digijet.  There is:

* Static setting (just the twist of the distributor -
sets the baseline for centrifugal and vacuum)
* Centrifugal advance (rpm based advance... seems to
kick in around 1600 rpm or so.  Where does it max out
at?)
* Vacuum advance (one half of the vacuum canister)
* Vacuum retard (the other half of the vacuum
canister)

Static and Centrifugal are pretty straight forward.
The vacuum advance/retard is a little more confusing
to me.  First off, does the vacuum canister actually
ever retard the timing?  Secondly, the vacuum signal
adjusts the timing for engine load (i.e. lugging up a
hill at low rpms), right?

Is idle the max advance condition (as far as vacuum
goes), and then it just drops proportionately with a
lower vacuum signal, or...?  On a standard 1.9L wbx,
how much of an effect of the timing does the vacuum
signal have (5deg...50 deg)?  I guess a more direct
question is: at idle, if you unplug the vacuum line to
the distributor (and plug it), how much does the
timing change by?  I'd be curious to hear with people
with 2.1L wbxers with digijet FI have as a result,
too.

As you can tell, i am a bit unclear as to how the
different aspects of the digijet distributor work
together to proved a well-tuned timing map...

Thanks for any insight,
-Damon

'84 Westy "The Van" w/2.3L WBX
Vancouver, BC

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