well its on a 71 340 with a 727 but the rear end is a stock 7 1/4 .....changing that soon....but it has been converted to an electric choke and sits on top of a holley street demon intake which is a single plain intake and that in its own might be the reason for the "lag" it has a hard time starting in the mornings but once the carb is warm it has no problem but when i put it on the street i romp on it and it feels like its starving for fuel and like i said it might be the intake doing this