bumpstart

LPG is a relatively slower burning fuel than petrol under most conditions
usually in NA mode it will use higher initial timing ,, but curiously same or slightly lesser total advance than petrol motors at higher rpm

increasing charge density increases flame speed so at peak engine efficiency or boost the timing is more reflective of normal petrol need
-- another time and place needed to explain LPG's inherent burn characteristics


the point is though,, with just leading timing,, i certainly do get away with more ignition advance
-- nothing in the scale of 15 degrees or so,, but set up as is at the moment more like 5 degrees
( and when the retard pot failed ,, as much as 10 degrees more )

i point out that boosting with 15 psi and effectively around 22 BTDC timing would have been fatal ,, even with LPG,, had the trailing timing been hooked up
( and trailing some 8- 15 degrees behind the leading )

previously on LPG with the full sequential ignition ( and trailing ) i would have had the timing more akin to 12- 15 degrees at 15 psi to ward off the high inlet temp detonation ,, and it wouldn't have lived with 22 degrees !