Lord Darby (4"RL)

Hi Tim
In my experience the arch does not make that much difference in this matter as the small o6os I have fired don't have the arch and the practice is the same you sometimes have to open the doors a bit to get total combustion

I was going to comment the same as Tim regarding the arch and lack of baffle plate. With models i think you'll be ok so long as your not working hard up a hill with the doors wide open which you wouldn't as the draft created by the draw will cause complete combustion anyway. ]

My doors sit slightly ajar by about 8mm. This seems enough to create a ball of fire above the coals and not get sooted out.

When you are working the engine hard there is no need to have the door open as there is more than enough air being pulled in to have total combustion in most cases