[olddog]

It occurred to me that the OP has never actually explained the bad manors. We have all assumed that he just doesn't like the low rpm tendency to want to buck and hop if you try to make a quick blip on the throttle or open the throttle too much at very low rpm.

An engine running too lean can hesitate, even pop up the carb and backfire. It can also cause surging. Not all engine builders take the time to tune anything other than WOT on the dyno. In fact most do not. Especially if they are a large shop that builds cookie cutter engines (100s of the exact same engine). They may tune one or two and just set all the rest the same.

Then there is the timing. The big three engineers spend hundreds of hours finding the ideal timing to make maximum break torque at every rpm and every % load combination. Then they change the commanded fuel ratio and do it all over again. All this while measuring emissions. This is how they maximize mpg, minimize emissions, and get good manors and good Hp.

Most engine builders will not even make a low rpm dyno pull. This is the danger zone where engines self destruct from detonation. They will argue that you should never operate a performance engine in that range anyway. Fair enough, but this is the proof that nobody has spent the time getting a good tune down in the low rpm range. This can be done with EFI, but there are not many tools to work with on a carb and mechanical distributor.

Does your engine have vacuum advance? If not, one less tool, and a terrible way to run a street engine. It's fine for a race only engine, because it will spend little time at low rpm.

I have digressed. My point to all this is: Take your car to a good tuner with a chassis dyno. The best dyno for this is the type that can hold a set load or a set speed and can change this on the fly. I forget the name for this. The dyno that just spins a heavy wheel is better suited for WOT pulls. You can do some tuning, but not everything. Then they have to take the car out on the street to finish up.

With the engine well tuned, it may resolve most of your issues. Then it is a matter of training the driver not to try to run the engine where it does not want to run. At some point in time you just have to realize this is not your fathers station wagon. It's a fricking race car, and you need to treat it as such.