I purchased this to replace the worn out Carter 500 on a mildly modified Ford 300 inline 6. Annular discharge boosters were the deciding factor; it's like having an Autolite 4100 with metering rods for better adjustability and fuel control through the throttle/ rpm range. I haven't put a great many miles on it since calibrating it, but have monitored air/ fuel ratios and it's lean where it should be and riches up when it should. So far fuel economy is 21 mpg which is startling in a 1979 F150 4x4, even with an overdrive. Power production is very good, it idles well, and starts easy.