Adding FB intake vent. Above flame level in FB OK?

[Tallbald]

My OK Joe Highland only has about 6 1/2 square inches of vent into the firebox as best I can determine. Calculation formula calls for about 10 1/4 square inches of air intake.
Prefer not to leave the door open for more air, so I will add another adjustable vent to the FB made from adjustable off old smoker. The area at the top half of the FB on the end looks like a good spot but the air will enter above the flame level. Is that a problem? I searched here but cannot find an answer already posted.
Thank you all. Don.

 

[Rings Я Us]

Dave Omak has answered this a few times. Maybe you can pm him for a quick answer.
Daveomak*

But I think your on the right track..

 

[Tallbald]

Thank you. I will do that. Tomorrow is warmer and may be able to do the work before a planned smoke this weekend. When you say "on right track" though do you mean above the flame is fine or not? Thank you again. Don.

 

[Rings Я Us]

Often you see an upper vent on the fire box and a lower vent.
Also adjustments to the stack inside the cooking chamber. Added pipe to increase efficiency.

 

[Tallbald]

I'm ready to add 5 inches to the stack externally (longest straight section of old stack I had) and have a 6 inch section of steel extension inside from the stack hole down to a half inch above the cook grid. Maybe that will help on draft. Don.
I did send the PM as you suggested. Don.

 

[daveomak]

Do you have a picture of the firebox door and that end of the FB.... That would help with an assessment...

Below are examples of great functioning air inlets on fireboxes... A quality smoke on food needs plenty of air... The lower inlet allows for adjustment of the heat output of the fire... The upper inlet allows for moving that heat from the firebox to the food cook chamber.. Your smoker must be air tight for these adjustments to work properly...
The lower air inlet should be (Cook Chamber Volume in cubic inches X 0.001 = FB air inlets in square inches... then the lower would be 80% of that number and the upper 20% of that number)
FB volume is calculated... D X D (in inches) X 0.7854 X length in inches.. = volume in cubic inches X 0.001... then X 0.8 & X 0.2 to get the "square" inches of each inlet..


..

 

[Tallbald]

Wonderful! Thank you all so very much. Don.
Oh also. It was late last evening and I didn't explain my lack of photos. I hope to take photos of my Highland modifications tomorrow after I add a few more today. Our bitter cold and snow have prevented me from doing so up to now. Thanks again. Don.