Adjusting Height of Lower Stone
Balancing By Adjusting the Flame Control.
The BS has a very simple tool free way to adjust overall top to bottom heat, especially if you are only making a pie or a two at a time, by adjusting preheat times and the flame control on the front of the BS. Say you find that the bottom is burning before the top browns. One option is to use a shorter preheat time and set the flame at the front to a medium low. When you launch the pie, you then turn the flame up to full. The air in the chamber will increase its temp much quicker than the lower stone, which has greater mass, and so the top should brown quicker while the bottom should now take later to brown. Of course, this will not work if you are baking multiple pies unless you turn down the flame, and give enough time to allow the lower stone to cool down. That is why many of the other mods are used.
Adjusting Height of Lower Stone.
The BS has a pretty simple design. The a large portion of the flame heats the bottom platter, but a portion of the flame goes to the right and around the platter and heats the upper stone. Not a great photo, but you can see some of the flames curling around and going past the bottom stone.
Another photo, the tank was nearly empty, so the flames did not shoot as high as normal, but you can still see flames going around and over the bottom stone.
Once both stones have been preheated, the upper stone will be much hotter than the lower stone ( I have measured temps over 1,000 F on the upper stone) , but the lower stone is much more efficient at delivering heat to the bottom of the pie because the pie is resting right on the lower stone, and is many inches from the upper stone. If you are not happy with the balance between top heat and bottom heat, one adjustment that should cost nothing is changing the height of the lower stone. There is a stop collar on the rod that holds the platter. If you move the stop collar down 1/2 inch, the platter will be raised 1/2 inch higher, which will cause the top to brown a little quicker. If you move the stop collar up 1/2 inch , the top will brown a little slower. The actual change to top balance is not that easy to predict because as you raise the platter, since the heat shield is sloped inward, you also decrease the amount of hot air that can pass to the right of the lower stone.
To adjust the Lower Stone you will need a 3 mm allen wrench, and may need a lubricant to loosen the set screw. It may have two set screws. First, use the allen wrench to loosen the stop collar which is on the rod attached to the platter. If it won't move, try some lubricant to loosen it. Then move it and reposition the platter to the correct height and tighten. Most users seem to prefer setting the lower platter 1/2 inch to 3/4 inches above the front opening. Then tighten the set screw so the platter won't move.
A great improvement would allow the user to change the height on the fly. But that doesn't exist on the BS. So set it. Try it for a few pies, if your aren't happy, change the height slightly and see if that works.
NOTE, the newer BS ovens come with a bearing mounted on the rod, and that sets the height of the lower stone so it is not adjustable.