Brent, I wish I could but its on long-term loan to me and a favourite bed-time read I might add. (admitted anorak).

I wish too I could afford to travel to Kiwi land and have the experience of setting the idle mixture for you:

Sect 3, Chap 1, Page 533 "Reset the engine to 450 ± 10 rpm and with a brake loading of 4.5 bhp., check and synchronise slow running to give 6" of blue flame (maintaining 450 ± 10 rpm - 4.5 bhp) with engine hot, open exhaust."

What I can do, is ask the owner but don't hold your breath, I'll see him this Wednesday.

R.