Throat size and even temps

[calvinandhobbes]

I’m a newbie to the world of offset smokers so I’m trying to learn how to harness my smoker. I have a 32x20 traditional offset with a firebox that is 18x20 (168% larger than necessary). I bought it unaware of any calculations for firebox or throat size but I like the idea of doing some modifications to make it not only more efficient but also more personal. It’s a solid weld with 3/8” steel and quality built. The throat measures 17x9 in an elliptical shape (really it’s football shaped) for an area of approx 120 sq inches. The calculator calls for 45 sq in throat so I put a cookie sheet that cuts the throat opening in half. If the cookie sheet is in place, my temps become much more uneven to approximately 80 degrees warmer at the FB end than the chimney end. However, without the cookie sheet in place and the throat wide open, I only have approximately 20 degrees difference across the cooking grate. I was planning to modify the throat with a steel plate that would give me an opening area of 45-50 sq in but now I’m hesitant it’ll only create a greater temperature variance. Any insight as to why I have such a greater temp difference across the grate when I shrink the throat size as opposed to the throat being wide open and oversized? And any suggestions on modifying the throat size, should I do it or perhaps not?

[Back9Q]

Pit calculators aren’t be all end all and should be used as starting point. Most of top builders these days have an oversized FB. If you are only getting 20F difference side to side I wouldnt mess with it and leave as is. That is pretty good for an offfset

Edit: the larger opening is likely allowing pit draw better allowing burn more cleanly

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[towtruck]

I believe you will need to make sure all the numbers match the calculator to benefit from them. Fire box size, stack size, and throat all play together and to play well they have to be in sync.

Have you played with the pit long enough in its current state to know if you can control it? I would be doing some test cooks to learn the pit the way it is. After a dozen or so cooks you should have an idea if it needs mods.

[Dirtytires]

Yep....should bring everything into specs before you call it a failure.

If everything is oversized and it runs fine, leave it alone. It will probably burn less fuel being properly sized but that may not be worth the work if you are happy as is.

[breavis]

I have a Chargriller that I modified the throat.(See my thread if you get a chance). I've only cooked once but I could tell a difference for the better