Hmm, the dyno guy use your fuel pumps or their own? If they went with theirs and bypassed yours you can eliminate fuel delivery. The dyno's air fuel ratio show a lean condition at a specific rpm then enrichen as the rpm got higher or once the lean condition started it stayed for the rest of the pull? The engine is stationary on the dyno so that would eliminate fuel stacking.. You have the same prob with two engines so not camshaft/ heads suddenly breathing better at a specific rpm. Same carb each time, why not test with a known carb? that way you could confirm or discount the carb or the fuel delivery as the problem. They guys at dyno shop I had mine on also suggested a Holley to me. Mine was running rich with the Edelbrock, we changed jets and needles five times and thought we'd reached the limit. After the last pull we swapped out for a Holley 750 they use at the dyno. I picked up both torque and horsepower with the Holley. Since I do most of my driving at normal street speeds and do not compete in racing, I just left the Edelbrock on. Maybe if I win the lottery I'll buy one of the Holleys but right now I can't see spending the money to get seven more HP at an rpm I seldom run at. I built mine for torque.
