Now that I've read Dave's response, I realized that I may have misunderstood the opening post regarding a bigger box...I was thinking bigger smoke chamber...
..silly me!
The stock chip box in the 3405GW seems small and chincy, but I never had issues with getting long smoke times with a mix of chips in the bottom, then some small chunks in amongst the chips. The chips start earlier than the chucks due to more surface area, then as they are getting burned-up, the chunks take over and smoke a lot longer. I don't soak the smoke wood (that's another discussion that's been beaten quite hard), I use the chip pan cover, I start on high flame until I start smelling smoke out the vent, then dial back the flame to the desired chamber temp. Sometimes I start with the cabinet door open with high flame, as it may take a few minutes to get the wood smoking, and chamber temps may climb above target temp with the door closed. Anyway, I have run for anywhere from 4-6 hours without adding smoke wood with pork butts or picnics on the grate for all-nighters...a good mix of varied sizes (with the majority being chunks) seems to do the trick for length of smoke generation.
The main thing to remember about using smoke wood chips or chunks is that if you can smell smoke, you're smokin'. You don't want a heavy white smoke, though it may start out this way, then settle in to a nice thin smoke after a few minutes or so. The initial onset of white smoke is mostly water vapor flashing off from the smoke wood...once the water vapor is gone, thin smoke should soon follow. If the smoke stays heavy, too much heat or air is getting to the smoke wood. Get the right balance of heat and air to the smoke wood, and you're all set to go. If you need to, you can play a little trick to limit air getting to the wood by covering the slotted vent holes of the smoke wood box from the inside with a bit of foil, or even place the wood inside a foil pouch, poke a few holes in the foil, then put it into the chip box. There are probably a dozen more ways to control air getting to the smoke wood, and also you can do mods to raise/lower the smoke wood box in relation to the heat source for even better control of smoke generation to compensate for varied burner settings and btu output with seasonal weather changes, or when mother nature is trying to throw a wrench in your gears with wind, rain or snow.
There are lots of ways to make things work in your favor...you just gotta find that sweet spot sometimes and roll with it.
And, yes, I forgot to welcome you to the SMF family!
Eric
