Go to the Recipe: Wood-Fired Brick Oven Set-It-And-Forget-It Tomato Jam
Do you try to keep the temp at 400? Or are you letting it cool so that they are barely simmering over time?
Initial heat will be 400 and then it will taper off slowly. You do not want to maintain heat but use the stored energy from the oven to carry through the cooking. Low and slow.