With help from Captain Scarlett on this thread https://www.rodsnsods.co.uk/forum/topic/pinto-efi-220569 it's proved that ignition timing WAS\ IS spot on at factory 12'BTDC.
As I'm working my way 'out' from the engine checking as I go the only thought that springs to mind is that I've disconnected the PCV set up.On the early engine there is a T pipe AFTER the AFM that connects to the oil filler cap and already metered air ( having passed through the AFM ) is drawn through the block up through the crankcase and then via the pressure shuttle valve into the bottom of the inlet manifold.
I had to do this as on the LPG set up I'm running it would have meant LPG being drawn through the engine instead of air!!
The T pipe is now blocked off at the AFM so I can't see this causing a problem as the metered air quantity ending up in the engine is still the same albeit slightly less contaminated. Anything I'm missing re this ?