7.2.2 Modifying the Hondo/NBBD or SnP Pro smokers
DO NOT use galvanized steel sheet metal for any of these modifications.
The zinc in a hot environment can give off vapors that are toxic. Use only plain steel or
The Hondo/NBBD and the SnP Pro are both off-set firebox smokers. Both
can produce excellent barbecue right out of the box. However, there are several
modifications which can improve their performance and ease of use and therefore enhance
your own enjoyment at the same time. These modifications may be applicable to other,
similarly designed smokers.
Modification 1 - Improve heat uniformity in the smoking chamber
Why? - The design of these smokers is such that the firebox is at one
end and the exhaust stack is at the other. In addition, the hole between the firebox and
cooking chamber is located about mid height of the cooking chamber. Since hot air rises
and since the heat source is much closer to one end of the cooking chamber than the other,
the actual temperature at the grill level varies greatly end to end.
HOW? - There are two modifications offered by the List members.
A The easiest method is to obtain a piece of 12 inch or so aluminum
flashing. Roll this flashing up so that it can be inserted into the smoke stack from below
(remove the grill to gain access). Reinstall the grill and pull the flashing down to the
level of the grill. If you need additional grill space, just push the flashing up into the
stack to clear whatever you are cooking.
B This method saves grill space but requires the services of a good
welder. Obtain a 4-inch piece of steel pipe (one List member used a diesel exhaust stack
from a semi). Don't use a 3-inch pipe (same size as presently exists) as this is too
small. Remove the existing stack and weld a patch into the hole. Cut a hole in the side
wall of the cooking chamber at the end furthest from the firebox and about an inch above
the bottom (so as not to allow grease to enter the new smokestack). Now, either bend or
cut and miter the 4-inch pipe so it has a 90 degree bend in it and weld it to the opening
just made. You will also probably have to weld a flat bar support (hanger) near the top of
the cooking chamber to support the pipe, between the pipe and chamber side wall. The new
exhaust stack should be at least 30 inches from the elbow to the top. Clean and repaint
and you're ready to cook.
C Some List members who have made the change to a 4-inch exhaust stack
have taken the factory stack and installed it in the firebox. This gives an additional
level of control--to vent heat when the cooking chamber gets too hot and to let out the
thick smoke when new wood is added.
What these modifications do is force the combustion gas to escape the
cooking chamber at a lower level, thereby maintaining a more uniform temperature in the
chamber both side to side and top to bottom. The 4-inch exhaust stack draws much better
than the factory 3-inch stack, giving better heat circulation in the cooking chamber.
Modification 2 - Eliminate the radiant heat hot spot
WHY? - The hole between the firebox and cooking chamber is wide open!
This is great for airflow but bad from the standpoint of thermal uniformity. Any food
close to the hole will not only be exposed to the high temperature combustion gasses but
also to the radiant heat from the fire. Just like sitting in front of a fireplace in a
cold room, the side facing the fire picks up radiant heat and gets much hotter than the
side away from the flame.
HOW? - There are four methods offered to solve this particular problem.
A Cut an aluminum piece of flashing large enough to cover the firebox to
cooking chamber opening from its highest point down to a level about 1/2 inch below the
grill level. Make sure your grill is at its lowest normal working level. At the top of the
cut piece of flashing, include enough additional material to engage the top bolt and the
next two lower bolts that hold the firebox to the cooking chamber. You'll have to bend the
flashing a bit to clear the small shelf' at the top of the cooking chamber to
firebox opening on the NBBD. Push the flashing up against the bolts to mark their
locations. Drill three holes slightly smaller than the bolt diameter at these marked
locations. Now, either push the flashing in place over the exposed ends of the bolts or
remove the nuts one at a time and install the flashing secured behind the bolts.
B This modification is similar to number 1 above except that the
flashing is sized and fit to extend INTO the cooking chamber instead of just vertically
blocking the opening. For this mod, you want a piece of flashing that will hook to the top
bolt and end up at the grill level but slanting down at a 45 degree angle. You will lose
some grill space but you will maintain the opening at its original area and at the same
time, force the hot gas out below grill level and protect the food from radiant heat.
C-a This modification was developed by Mike Roberts and is the most
ambitious of all. It consists of a welded piece of steel at the opening and several more
shields as you travel the length of the cooking chamber. First, a piece of steel is cut to
close off the firebox to cooking chamber opening to just below grill level. A second piece
of steel is welded to the bottom of this one, at a 90 degree angle, to force the exhaust
gas further into the cooking chamber. This second piece is cut to the width of the first
vertical piece and is 6-1/4 inches deep into the firebox. In effect, you will end up with
a shelf' just below the grill level that extends 6-1/4 inches into the cooking
chamber. All the exhaust gas has to pass under this shelf to escape the smoker. This
baffle could also be fabricated from heavy gauge sheet metal and bent into shape without
needing any welding. The sheet metal baffle would then be bolted onto the top two bolts
holding the firebox onto the main smoker section. Next, 3 additional plates are cut out
and set in the smoker at the same level, basically extending this shelf. Each shelf is 5
inches long by the width necessary to rest on the chamber sides at the same height as the
first shelf. The edge of each shelf (nearest the chamber walls) has a cut out made to let
heat rise as it progresses along. The cutouts are 1/8 X 4, 1/4 X 4 and 1/2 X 4 inches for
the first, second and third portable shields respectively (you will end up with an
"H" shaped piece of metal with a really thick center section). The shields are
placed in the chamber about 1/2 inch apart so the total length of this shelf becomes
22-4/3 inches (6-1/4 plus 1/2 plus 5 plus 1/2 plus 5 plus 1/2 plus 5). According to Mr.
Roberts, this evened out the temperature, side to side, to within 20 degrees. NOTE - This
modification could probably also be done using flashing to avoid the expense and time of
D This modification accomplishes the intent of A and B although not to
the same degree of effectiveness. Get an aluminum tray which is approximately the width of
the firebox to cooking chamber opening. This tray should be tall enough to block the top
of the opening and approximately 3 or 4 inches wide. Fill this tray with water and set it
in front of the opening. It will block some radiant heat, force the gasses below the tray
(to some extent) and boil off and maintain a more humid cooking environment. NOTE - This
mod is only for the lazy and does not work anywhere near as well as the other three.
Modification 3 - Add a drain connection to the smoking chamber
WHY? - The NBBD and NB Hondo do not have a connection to drain away
grease from the cooking chamber. Although not an absolute necessity, a drain hole can be
HOW? - Weld a 1/2 or 3/4 inch piece of pipe or a 3/4 inch half coupling
at the far end of the bottom of the smoking chamber. Attach a shut off valve and you have
a drain connection. NOTE - Some propose to install a 90 degree elbow before the valve.
This arrangement allows you to do several things. You can put water or a
combination of water and seasonings in the bottom of the smoker during its use. After
smoking, simply drain away the leftover liquid/grease. You can also eliminate the use of a
grease drip pan although this really isn't recommended. Additionally, should you ever want
to clean your unit, you can fill it with cleaning solution (Simple Green works well),
scrub it and then drain away the spent mixture.
Modification 4 - Improve the tightness of the unit openings
WHY? - These units are nicely made for the money but they are not
precision made. Therefore, the doors and openings leak (allow air and smoke in and out)
and thereby reduce the cooking efficiency and your ability to control what's going on.
HOW? - Install a gasket. A BBQ List member has evaluated a method using
a high-temperature silicone sealant to make formed-in-place gaskets for his NBBD. He
reports that the silicone material lasts for about a year and then comes apart and falls
off. He was happy with the results and feels that it was worth the effort and will repeat
the process each season.
Another List member suggests using flat fiberglass gaskets made for
wood-burning stoves. The gasket material comes as a thin rope and is secured to the smoker
body with a high-temperature adhesive.
HOW? - Do some body work. Another List member reports that a
poor-fitting door can be made to fit better with some auto body type hammering with a
dead-blow hammer and wood blocks.
HOW? - Another List member reports extending the exhaust stack increased
the draw through his smoker and eliminated the smoke leaks on the doors. Another List
member reported smoke leaks coming from the doors before he replaced the factory exhaust
stack with a new 4-inch diameter stack on the end of the cooking chamber. The new stack
extended 32 inches above the elbow. After the new stack was installed, all smoke leaks
Modification 5 - Improve the thermal efficiency of the unit
WHY? - These units are made of fairly light gauge steel. They heat up
and cool down rapidly in response to changes in the fire intensity and outside weather
conditions (wind and temperature). Adding fuel generally causes a temperature spike and
letting the fire go too long without refueling generally causes a dip.
HOW? - Line your cooking chamber with firebricks. Remove the upper
grates and set firebricks all along the bottom. Wrap them in aluminum foil to ease
cleaning. While adding bricks will naturally extend the amount of time it takes to
initially get the unit up to temperature by 15 - 30 minutes, it will be much more tolerant
of fires which get too low or those times when you add a few more lumps of charcoal and
the fire intensity subsides until the new fuel catches. The bricks hold heat and will tend
to stabilize the temperature. They will not prevent temperature spikes but they will
prevent the dips from being as low before the addition of the bricks. This can also be
done to the firebox if you have sufficient room.
HOW? - If you are going to make modification 2 'C', use thick steel
plates for the lower distribution plates. A steel plate that is 3/8 or 1/2 inch thick will
add additional mass to the smoker and help to stabilize temperature dips.
Modification 6 - Increase the volume below the fire-grate
WHY? - On some units, the position of the fire-grate is such that after
a long day of cooking, there is very little room left under the grate for air to get in.
This space is filled with ash from the fire so combustion efficiency suffers.
HOW? - Raise the fire grate. This can be accomplished by welding some
angle iron to the sides of the firebox at the desired level so there is more room for ash
to fall into while still having sufficient room for combustion air. Another method would
be to obtain some 1/4 inch steel rod. Drill four holes (two in front, two in back) of the
firebox at the level you want your grate. Push the rods through the holes and set the
grate(s) on the rods. If you use two grates, you may have to increase the number of holes
and rods accordingly.
Modification 7 - Improve temperature indication
WHY? - No temperature gauge comes as standard equipment with these
units. Without something, you'll be hard pressed to maintain your desired temperature.
HOW? - There are a few proposed solutions:
A Buy a thermometer that will fit the hole in the door. Just remember,
the location of this thermometer is higher than the grill and will give a somewhat higher
reading than the actual grill level temperature. Also, if it is directly above a large
piece of meat, your initial temperature indication will be lower than the actual
B Obtain a good quality candy or meat thermometer that has a shaft at
least 4 inches long (temperature range about 150F to 350F). Obtain two matching corks,
each about 4 times the diameter of the thermometer shaft. Drill a hole through the center
of one of the corks (top to bottom) just slightly smaller than the shaft diameter. Now
drill two holes, one to the left of the cooking chamber door handle and one to the right
(about 18 inches apart). These holes should be sized so you can push the cork in about
half its height. The holes should put the shaft within an inch of the upper surface of
each grill. Now you can monitor the temperature at the grills more accurately. Plug the
unused hole with the undrilled cork and swap positions as desired.
NOTE: - You can use the existing hole provided for a stock thermometer.
However, it's several inches above the upper grill and that location will read somewhat
hotter than the grill level itself.
C The preferred but more expensive fix is to obtain a Sunbeam or Polder
electronic remote reading thermometer. They can be purchased for around $25 to $30 at
kitchen shops or stores such as Service Merchandise. Push the probe through a small piece
of wood or a cork so that it is not in direct contact with the metal grill, set it
anywhere on the grill, close the door and you can read the temperature at the remote
display. Very accurate, very easy.
[I have seen many references to 'tuning a pit'. Can someone please
explain what this refers to?]
'Tuning a pit' refers to making it cook with an even temperature from
one end to the other. Usually, this is accomplished with a series of steel baffles,
plates, or tubes. These direct the heat and smoke from the firebox across the bottom (in
most cases) of the cooking chamber. The object is to allow the heat to rise at intervals
to provide for an even temperature throughout the smoker. It basically disperses the heat
where it's needed instead of all coming in at the firebox end.
The object of pit tuning isn't to dissipate the heat but to make sure it
is distributed evenly throughout the pit, ideally eliminating hot spots. If you heat a
tuned pit up to 250F the whole cooking area will be at 250F.