Had a stock 1968 383 4 speed car with 3.23s. It would not spin the tires from a roll in first at any speed. 10 mph is probably the worst speed/rpm to hope the torque challenged 383 will spin the tires. What is that? 1300 rpm?

From a roll in first at 3000 rpm, it should jump pretty good, but still won’t spin the tires.