I have been driving my 40 Ford pickup for about 5 seasons now. I guess we're never really "done" when you build a hot rod. Right now I'm trying to sort out a problem I'm having with the way the truck launces from a stop. In a nutshell: The truck would always lurch forward when accelerated. Part of this was the fact that I was using rear leaf springs that were longer from the axle forward than from the axle to the shackles and the springs would torque up when loaded and the truck would then lurch. I added a set of traction bars (not slappers) to control axle wind up and that helped a lot. However, the truck was still difficult to launch from a stop. It took very gentle use of the fast pedal to get it off the line smoothly. So, I incrementally changed the pedal ratio to require more pedal travel for a given amount of throttle opening. While this has pretty much solved the problem, it still bugs me as to why this had to be done. The pedal, cable and throttle linkage all came from the same donor as did the engine. A couple of years ago, I installed a tachometer. A couple of things I noticed by reading the tach were: The engine needs to idle at 1000 RPM in park to yield 600 RPM in drive and The engine never gets much past 1000 RPM before the truck launches. I have other OT vehicles with automatic transmissions and tachometers and all of them seem to initially climb to about 2000-2400 RPM as they start to move out. Another thing is that although the truck would always launch with a lurch, from that point the truck would seem rather slow on the uptake and my best acceleration would happen in 2nd gear as the engine would get into it's optimum torque range (235 ft lbs at 2400 RPM) Now I'm wondering that even though the transmission was a rebuilt unit(supposedly a rebuilt converter as well) Could it have been assembled with the incorrect converter? Could I have a severe mismatch of torque converter stall speeds that I can't get the acceleration to behave normally? This is an 89 700R4 transmission. I'm seriously thinking of buying a converter in the 2400 RPM stall speed range and trying it out, thinking that letting the engine get up to a speed where it's making some torque would help. Your thoughts please.