Lawandorder I was running with 500 - 550F clean and 600+F dirty stack temps too. 2 things that were a consideration.
1) I never adjusted primary air.
2) I do not have a barometric damper in flue (finished basement don't want dirt and noise etc).
I just cleaned complete boiler. I had tried to adjust primary air before but black knob & screw would not make contact with lever for damper. Reading on this forum I found that the lever can be adjusted by backing off 13mm nut and repositioning angle of lever, re-tighten 13mm. To get this in the right spot can be a PITA. ( have 2 x 13mm or 1/2" wrenches, shut power off to boiler ) Then you can choke down the blower's air supply with the knob. I have mine choked down quite a bit, yielding around 425F+ stack temps. Below 400 my gassifacation seems to stop and my boiler temps start to drop.
It was really obvious after 2 fires that I was using less wood.
I have started to look at Barometric Dampers again also. I'm in the process of trying to find a damper similar to Hannson's.
http://www.youtube.com/user/hansson30#p/a/u/1/cEycuK_9Zb4
Has anybody seen these for sale. These have a gasketed seal and would be more suitable for the location of my stove. There is a distributor in NJ and I will see what he has available during the week.
Your smoke ? Have you cleaned stove completely, including blower fan blades, air holes in the top of the top loading door, floor under HX tubes, HX pipes and chiminey ? Is you steel door above HX tubes closing tightly ? Are you getting air through the holes in the floor where the secondary air is.
Are you getting good gasification, where the ceramic is turning cherry red ?
If you wood is possibly a bit wet try re-splitting in to smaller pieces around 3X3's.
It's odd that you smoke ( not burning hot ) but overheating ( reduced flow ).
Over heating ? Variable speed circulator turned down by mistake or Tremovar isn't opening up.