I agree. The various vacuum cans are confusing and poorly documented. Guys who fool with their engines would be better served with an electronic spark controller, then they could tweak spark timing vs (rpm & MAP) to their hearts content. There was one named RapidGator which came and went. I expect the developer got a busier day job. I recall Kit was also working on one. One can do so with a Holley Commander 950, and perhaps others fuel injection controllers, if you use a GM 8-pin HEI module. A bit clumsy if not using the EFI part, but you can find the controller alone cheap on ebay, and could wire your own cable w/ just the wires needed for spark control. Can also add feedback O2 (wideband is best).
