oh wow so now were on new subject so. everyone saying 650 way to big then. i would think that make it run rich becouse it be getting to much fuel if its too big like u said it. i just went on hollys site and it recomends a 570. this kinda sux but kinda makes sence. but could u explain more why 650 is so big. i thought only differnts would be the jets? like i said i am 19 so i didnt grow up with carbs just it was one i had sitting around froma motor i but in catalina.

 

the "factory header" i dont no wht he was talking about then up he said they will fit my 302 heads . and there shorteys

 

Negative, the 3sp toploader has a 2.42:1 1st, 1.61:1 2nd, and 1:1 3rd. 1st gear is horrible for off the line, and the spacing between gears is horrible as well.

 

Carbs are rated in CFM - Cubic Feet (of air)per Minute. Higher CFM ratings come from larger venturis (the holes down the center of the carb). Larger opening means more air can flow through. An engine only makes so much vacuum, though. If you make the holes too large, you're going reduce the vacuum signal getting up to the carb. Less vacuum to pull the gas out of the carb, but the same amount of air getting in, which results in a lean mixture.

 

I thought the 3spd was a 3.03, my bad. Either way more gears = better.

As far as the carb, it depends. You can tune a carb that's too big to have a reasonably decent a/f ratio at least part of the time, but the problem is like Starfury said, weak signal. The weaker the signal, the less effectively fuel is pulled through the metering circuits on the carb, which means the a/f ratio won't stay nearly as consistant. Also the weaker signal means less emulsion(air premixing with the fuel) and less sheer(the fuel "breaking up" when it exits the booster), which all means less atomisation and less vaporization(which is also weaker from a weaker manifold vacuum from the larger carb). That means less power. Some larger carbs with out of the box tuning for larger applications are jetted for more air, so you could end up rich, but the weak signal doesn't want to draw fuel so you can end up lean. Usually the a/f ratio just ends up all over the place, too lean down low, too rich up high etc, and the carb won't tune right.

 

maybe the headers are off of a fox body 5.0.