Thread: Ported or non ported for vacuum advance

It's dependent on induction setup and fuel type - along with a host of other contributing factors.

There is no right or wrong.

multiple fuel types are always going to involve a compromise and perhaps this also means different vacuum sources are appropriate for each.

Back in the old days we always ran ported vacuum for manual cars and manifold vacuum for automatic to help the engine idle smoothly with the torque converter.
LPG required a different ignition advance curve than petrol. forty odd years ago I had an MSD type ignition box fitted that had a different advance curve for when using different types of fuel. It worked well , i think it went out of production a long time ago but there is probably something similar available.
Getting your distributor recurved is always a good idea, though probably not many doing this service any more since computers took over.
Set your timing to what ever makes you happy and gives good economy without pinging.

Ian
Bittern