Here is an area thats is confusing to many people. When you use something like an O2 sensor for tuning (Jetting) you DO NOT tune to a certain number (12.8 to 0ne) you tune to where the engine makes the most horsepower, THEN you look at the meter to see what it says. On my dyno, most engines make the best HP when I see an air to fuel ratio around 13.3 to 13.5 to one. On very high output engines( 2.0 HP per cubic inch, this ration even becomes greater ( 14 to one or higher)It is true, you can look at an O2 sensor to get you close, but remember, this is just a better starting point. On another subject, almost all Demon carbs are very lean ( jetting ) out of the box. I usually jet up 5 sizes before I even try it on the dyno. Now I know that most of the engines I am working with make more horsepower than normal, but unless you try bigger jets in any Demon carb, it will probably be too lean.

JOE SHERMAN RACING ENGINES