Petter AD1 not starting....

.... it has started and run in colder weather, it won't anymore, and nothing has changed. It has started backwards in the past, and I suspect that it's kicked back a couple of times. My suspicions are that the injection timing has drifted- how do I quickly check the timing? Do i understand... that you *add* shims to *retard* the timing, and vice versa? Hey, I'm new to this. Thanks for any help.

Yes, increase shims to retard start of injection.
The LISTER PETTER manual gives the procedure and settings on pages 55 to 57.
I googled it and http://engine.od.ua required me to allow notifications; I think that might have been a mistake, as I keep getting messages from some rather naughty ladies.
I suggest you use a different site.