If the engien stalls, it's the engine/tune. It has nothing to do witht he convertor. If the car bucks or lurches, the stall may be too low, or the idle rpm too high. As for them being called "stall convertors"..Think of it as slang. All torque convertors have a point at which the stator (the splined thingy in the middle of the oil pump drive snout that drives the transmission input shaft) is hydraulicly "locked" to the case (or convertor body). The rpm this occurs is the "stall speed". (In reference to the rpm a mechanical clutch assembly would be engaging at) Factory convertors have larger bodies, and are made with looser tolerances and different ways the fluid is managed. So the resulting "stall speeds" are low rpm wise. No convertor ever made will be exactly the same on every engine. So ratings you see are loosely based on what theoretically it should stall at. You dont know until you run it. Which is why some good convertors come including one free restall. Because until it's in YOUR car, you dont know exactly what it will do. Now, if you have a used convertor, and want to know exactly what it does, you can check. Torque convertors have two ratings. Brake stall, which is the test with the car not moving and revving until the engine doesnt go higher at full trottle. Some cars you cant actually even do that test at full throttle because it overpowers the brakes...lol. It also generates a TON of heat, so you want to be real quick with it. The second rating is teh flash stall. That you check by rolling slowly along in 3rd(If it's a automatic valve body you may need to go to a higher speed as it will downshift, and that skus the results a little) and then floor it. The rpm that the tach sweeps to before the car begins to accelerate is your "flash stall". The flash is usually about 2-500 rpm higher than the typical brake stall. Convertors are thier own animal. And what you pay is directly porportional to how well they do the job.
