Troy - my original post was a light-hearted attempt at humor with a lot of truth.
The Q-Jet is a very misunderstood carburetor, but is a wonderful unit for the street because of the small primaries (increased low RPM air velocity) and huge secondaries (for power).
There is now a really "user friendly" book on the market about tuning Q-Jets. The author is Cliff Ruggles, and the book may be acquired through your local bookstore, or Mr. Ruggles has them available as well.
For years, Holley has been a favorite with the hot-rod crowd because of the ready supply of tuning parts. But no one has ever accused a Holley of being fuel efficient.
The spread-bore design, whether it be Rochester, or the Carter TQ is simply better when it comes to driveability and fuel economy on the street. The big disadvantage to many hobbyists for years with the Q-Jet was lack of knowledge, and lack of parts. Mr. Ruggles has eliminated BOTH objections.
Anyway, good luck with your Holley; but as a suggestion, for best results pay a Holley guru to tune it for you.
Personally, I think it is too large. As a point of reference, Mr. Duntov selected a Holley 600 for the 365 HP/327 used in the 1965ish Corvette. And a 575 CFM Carter for the 350 HP/327 Corvette. How wild is your 305?
We would have suggested a 400 CFM Carter (square-bore) or the variable demand spread-bore for this application.
Jon.
