does anyone have an idea as to what the actual cfm the stock nikki carb is on the 79-85 rx-7 and if the carbs differ through the years.

 

They don't differ too much in flow; between 313 and 325 cfm. Earlier carbs have a larger choke opening, but Carl has found using his flowbench that the later carbs with smaller choke openings don't impede flow that much.
The Sterling Carb mod we offer flows 429 cfm to date.
We are striving for just a little more.

 

Don't know what the stock carbs flow but the Holley for stock port engine is 465cfm.

 

Ive actually seen it differ from 297- 325 (same carb) depending on the day. Air temp, humidity, baro pressure all affect the number. I dont do correction to this, too much math. Like Sterling said, theres no difference between the years to speak of, although the "big top" is slightly higher.