I find it easiest to think about the phases A, B, C;
*WITHIN* each phase, the START of one coil gets connected to the END of the next coil. (it doesn't matter which end of a coil you label start or end, as long as you're consistent, i.e. name all coil ends similarly).
If you adhere to that rule, you'll be sure that each of the phases is properly wired up, in a 3-phase alternator (single phase can be different, but you shouldn't use single phase anyway).
Finally, for a STAR (WYE) system, connect all the STARTS of all 3 phases together. (or all 3 ENDS together - doesn't matter); I assume your Hugh Piggott alternator uses 3-phase star, so the above applies.
But for a DELTA system, connect the END of one phase to the START of the next phase; so end of A goes to start of B; end of B to start of C; end of C to start of A.
So, to sum up: first make sure that all coils within a phase are properly connected, without coils being inadvertently reversed. When all three phases are properly wired, then connect them together, in either star (wye) or delta.
It's not difficult - once you know how to do it....
