How does it accelerate in 2nd. gear? If you get good performance in the lower gears, your rear end ratio and the cam don't match. The engine has to wind up into its power range before it will perform properly. It sounds like you're over-cammed, or over-carbureted, or both.
All torque converters have a "stall" speed, the speed where the engine can't accelerate any further with the brakes locked. Most stock converters will only let the engine wind up to 1800 rpm or so if you hold the brakes and nail the throttle. If you put one in with a 2,500 rpm stall speed, for instance, it lets the engine wind up tighter, and gets it into a better torque range for better acceleration. With a radical cam, a higher stall speed converter is just about a necessity, regardless of the rear end ratio. Otherwise, the engine is sluggish until it reaches its rpm for best torque. Most hot-rodders use too much cam, or don't match the converter to the camshaft!
Jerry
