I have asked this in the same time as other questions, but I have never felt that I have been given a convincing answer. This time I make a thread for it where all carburetor experts see it. I have been told that Holley makes every engine start and run, but not perform 100%. That it would be huge improvement if I change back to a Rochester. Lower fuel consumption, more power, less screws to adjust, or need to adjust at all. Just fantastic. Let's start there. Is this true? Sounds logic. A Rochester made for the engine should perform better, however, my Holley is made in modern times and should have some improvements over a Rochester made 47 years ago. Today I have the 770cfm Holley Street Avenger (80770-1). (LINK TO WEB) It works, but I want the best. Q: I notice that this one has vacuum secondaries. What have Rochester, vacuum or mechanic secondaries? What is good and bad? So I wonder: 1) If my Holley is a keeper. 2) Or should I get a stock 1968 Rochester. 3) Or get 1969-70 intake manifold and 1970-1974 Rochester. - And why one choice is better than the other. Some say that 800cfm is not necessary, but it don't seem to be negative? I have larger exhaust system, if anything break I would probably buy something more improved which I guess would appreciate more gas. Some say that the improvements are not doing much anyway, but they do something? Thanks.
I think it all comes down to what you are comfortable working with. A carburetor meters the flow of fuel/air to an engine. Almost any of them can be set up to work correctly for you, if you put enough tuning time and effort to it. Now, that said, here is why I like the quadrajet, and have created my business to build them. Quadrajet meters air/fuel all through the power band, and will only supply the necessary cfm that the engine needs at the time it needs it. You can't over carb and engine with the quadrajet. Small primaries make it great for cruising around. quick throttle response and excellent fuel economy. Quadrajet allows very specific tuning in all ranges. Sure is fun to go fast with a Quadrajet and spend much less money on the carburetor than other brands. 68 is a better design than the 66-67 for sure, but 69-74 had better design than the 68.
One thing at a time. First make sure you have a healthy engine. If something basic is wrong, carburetor changes and ignition adjustments won't fix it. Compression must be normal and valves must seal. Check that first.
