Starting a 412

[Oliver]

Hello,
I've finally got my Beaufighter running and MOT'd. My main problem now is knowing if it will reliably fire up. It needs about 10 squirts of petrol on the throttle before it will fire up.
The timing is supposed to be set at about 2 BTDC. However I've found to start cold it's best set about 15-20 BTDC. This doesn't make sense, I thought when starting ignition would be retarded. When warm I can adjust down to about 4-5 Btdc with a smooth tickover, but then it is hard to start.
I've rebuilt the Carter carb. The choke operates and when running seems to be performing ok.
The plugs and ignition are all new.
Have I missed something making it so unknown if it will fire-up?