ign curves

No worries.

since the original system ran on petrol, I would bet that the ideal ignition map for lpg is not quite the same as for petrol . it needs setting up on a dyno. or some careful guesswork.

Just give it a shit load more initial advance and it'll be fine :-)

Nedavno Pete M napisa:

As I understand I need more advance at low rpm, and less at high. I got few recommendation's from Australian newsgroup not to go over 28-30 deg mechanical advance over 3000 rpm.

Since I have 18 deg at 1000 rpm for petrol I think that I will not go much higher.

While I was searching for ignition curve for my distributor I've looked at lot of curves, and it seems that mos of them start at ~8 deg initial advance. In these cases you would add ~6 deg for LPG.

And that's why 18 looks a bit too high. So if I add ~6 more looks even more drastic.

I think I will add few degrees at low rpm, and limit at 29 deg at 3000 rpm.

My ignition controller has the option to set specific advance while engine is cranking, so I do not have to worry about stressing the starter.

Any ideas how does ported vacuum relate to unported? When do they equalize? I'll have to do some testing...

If you add too much the main symptom will be it won't start.

Nedavno Duncan Wood napisa:

As I wrote in my previous post, my ignition controller has the option to set specific advance while engine is cranking, so I do not have to worry about that.

My only concern is pinking. And if my ear is sensitive enough to recognize that.

Nedavno Pete M napisa:

Where did you get this info? I drew a graph, and I wonder if it is OK to put it somewhere on the web, in case someone else needs it. Unless you got this data on-line in which case you may post a link.

Autodata. I searched through the BMWs for your distributor part number.