Estimating food grid temp from top located thermometers?

[Tallbald]

So I'm a happy new OK Joe Highland owner who has made some helpful modifications to my new smoker. But as to the thermometer placement....
The factory did a beautiful job on mine welding the pipe thread fitments toward each end of the food chamber lid. I don't have a welder so should I decide to move the thermometer lower and closer to the cooking grid it would be a pale attempt to duplicate factory ways. Oh. I remove my thermometer between smokes to keep it in my home, and the factory pipe thread is a good quick way to put on/take off for me.
Is there a rule of thumb that would help me estimate the food grid temp when the temp up top in the food chamber, 8 inches above, is "X"? probably dependent heavily on insulation, wood species, and many other things, but worth an ask to a new , very interested fella.Yes I could try to borrow (I hate borrowing tools---or loaning them) or save yet more money for a digital remote sensor thermometer to investigate, but if there's a rule of thumb I've not learned, it would save me money.
I posted this in the wood smoker section because it's specific to that style pit. Please move if appropriate.
Thanks. Don.

 

[noboundaries]

Personally I don't know of any rule of thumb. Just stop in at your local grocer and pick up an inexpensive ($5) oven thermometer (see below). Place it on the grate next to your meat. Look at the lid therm, then take a peek at the grate therm. You'll have the difference figured out in no time.

Another thing you can do is replace the lid therm with a River Country adjustable thermometer. They run $15-$30. Might as well wait until the lid therm fails though. You use the oven therm on the grate to adjust the lid therm for a specific spot in your smoker.

 

[SmokinAl]

Exactly what I do on my smokers. When you know what the real grate temp is & what the lid therm is reading then you know what the difference is.
So if the grate is reading 225 & the lid therm is reading 250, you know basically there is a 25 degree difference.
So if you want to smoke something at 275, your lid therm should read around 300.
Al

 

[Tallbald]

Thank you. A simple, cheap and helpful suggestion that I will use. An oven thermometer would get very smoked up if used all the time I know, but for a couple good efforts to check as you suggest it would be well worth the cost. Maybe also would give me a ratio to kind of expect under similar conditions in the future. Plus I could clean it up afterwards and use it in our electric kitchen oven. Thanks once more. Don.