I was wondering if a 40 dlha dellorto side draft carb will work in my 1981 Mazda RX7 with the racing beat (side draft carB) intake?

 

It will work but it might be running lean tho.A 40 is a little small.I had a 48 on it but that was a hair to big for a stock port 13b.Ideally I think a 44 would be the right size unless you plan on porting the motor