Ignition timing on propane small block

I run straight propane on my '73 318 Dart.

With the recurved distributor I used to run until about a week ago I had the following numbers;
- 10° initial
- 32° init+mech
- 47° init+mech+vac adv.
At 24.5° init+vac adv. (Transmission in Drive @ 550rpm) produced highest engine-vacuum (20.7" Hg).

Use the lightest springs (or just one spring) in the distributor, just enough tension to keep the advance mechanism at bay during idle.
Advance should be 'all-in' at around 2400 rpm.
With vacuum advance, timing should not exceed 40-42 degrees.


Last week I installed a MegaSquirt and could now digitally enter the Spark advance curve, which really woke up low rpm drivability.

Here's the posting on my site where you can see the (ballpark) advance table which already woke up the engine nicely in just about all the RPM-ranges;
MegaSquirt MS3x ECU install in the Dart