Actually, Edelbrocks are more tunable than Holleys, with much better variable settings like metering rods, vacuum piston spring rates, and accelerator pump adjustments. It just takes a little bit of equipment and knowledge to do it right. Neither Edelbrock nor Holley is a suitable substitute for a factory-engineered carburetor that's been set up for the engine in question. Once compression, displacement, cam timing, or port/manifold shape has been altered, all bets are off. At the very least, a 4-gas exhaust analyzer and a few more pieces of test equipment are needed to check out whether the mixture, power valve setting, etc. are correct. After some time on the road, fuel mileage and spark plug condition can be pretty good indicators of a correct carb setup. On a dyno run, I've gotten as much as a 20 HP increase just by a jetting change.
Jerry
