Join Date: Apr 2013
Location: Columbia, Missouri, USA
Here's a question that's been bugging me for a few days: how does the Alfa engine accomplish the 'vacuum advance' function found in other cars? Obviously it works, I just don't know how.
There's no external mechanical action, so is it all centrifugal inside the distributor? I guess it's possible that the electronic ignition timing could influence the spark to occur at the leading- or trailing-edge of the rotor, but I don't know if that would be enough.
An old air-cooled VW will advance the distributor timing greater than 30 degrees at full-throttle. Both of my VWs have Bosch distributors with a combination of vacuum and centrifugal advance action.
Especially when considering the effect of VVT, I would think there needs to be more agility with the spark timing.
1988 Spider Veloce (with lots of 3D printed parts)