Trigger disc orientation help.

[Chris Wilson]

I am rebuilding a Formula 3 race engine.An Alfa Romeo 8 valve twin 
spark Novamotor.It came with Magnetti Marelli management for ignition 
and fuel.I am based in the UK,and the only source of info and spares 
is in Italy,where they speak little or no,English at the factory.The 
management is triggered by a disc trapped between the cam belt pulley 
and the front shoulder of the crank.I expected it to be pinned or 
keyed,when I undid the front pulley bolt,but it wasn't ...:-( The 
disc is free to rotate.There is no distributor trigger,or cam 
trigger.I faxed Italy,and received the reply that :

"At TDC on 1 or 4 ,one prong of the disc should be central to the 
crank pickup sender".

The disc has 5 prongs.4 at 12,3,6 and 9 O'clock ,and the 5th right 
next to one of the other 4,not spaced well away,like others I have 
seen.I am trying to work out if it matters which "prong" is opposite 
the trigger pickup at TDC.Should I use one of the 3 single prongs,or 
one of the pair adjacent to one another?If the adjacent ones,which 
one of them?Or doesn't it matter?Can it be TDC on any stroke,or 
should it be TDC on the firing stroke,if I use one of the adjacent 
ones? Hmmm...

Thanks for any help.


-- 
               Best Regards,
                        Kasper.