The basic orginal megasquirt does not control timing, it does control a on/off fast idle valve or solenoid. That said people have modified the s/w to do timing control with the orginal hardware.
What is being worked on right now is the 2nd generation megasquit that will do a) fuel, b) timing control and c) variable fast idle just like the OEM's do it.
If this is your first time using EFI I strongly urge you to tackle either the fuel OR timing control don't do both at the same time.
Meagsquirt will run just fine doing one or the other. Suggest you start with the fuel side and run a distributor. After the fuel tuning is done you can then lock out the ditributor mechanical and vacumm advance and tune the timing control.
Hope this helps.
