score of a lifetime..lol

txstang84 said
Looks like a few folks already beat me to it-this is why I asked if it needed to be rejetted...I've seen an 850DP on a 4.6 4V modular and it lives quite well. If the carb is putting out too much fuel it needs to be rejetted or have different pump cams or possibly smaller squirters or accel pump diaphragms. Otherwise, a carb is a simple air/fuel mixing device operated purely on engine demand...if it's jetted wrong, the size rating of the carb has next to nothing to do with how rich or lean it runs...

I was addressing the part of your comment that stated that an engine will only take as much fuel as it needs. A larger carburetor or throttle body will enable the engine to draw in more air yes, but one that is too big is almost as bad as one that is too small. On a fuel-injected car, a throttle body that is too big will put too much gas in the combustion chamber that just flows through the exhaust unburnt. It is much more of a problem on a carbureted car. There, an oversized carb will make the engine actually perform worse at part throttle. A simple formula for calculating the correct carburetor setup is:

CFM (amount of air the engine needs) = Displacement (in cubic inches) X Maximum RPM / 3,456

A lot of how the engine performs with different carb combinations depends on a lot of different factors such as dual/single plane intake, if it's a dp or vacuum secondary, engine rpm, car weight, transmission (auto/manual), even gearing can affect it, and a number of other factors.

Because of engine temperature, speed, and load, perfect carburetion is very hard to obtain. It does sound however like this carb is working great for his setup, that's awesome. Can he dial it in better, probably. It sounds like he got a great deal, but bigger is not always better and if it wasn't running well through all ranges of throttle, you are right he would probably need to re-jet the carb. I'm also sure you that you know more about carbs than I do and probably have a lot more experience. My knowledge comes from having read a lot about carbs and trying to understand better how they work so I can then apply that knowledge to my applications. Cheers.