I'm wondering if on an otherwise stock (for now) '73 Riviera, will I see any kind of improvement in the form of say, better throttle response or better performance off the line by putting something like a 750 or 800 Edelbrock on it with mechanical secondaries instead of the Quadrajet? I've got people telling me that I would, but my understanding was that the Q-Jet is one of the best carbs ever made, and I don't see what benefit I'd get from going from a 750cfm Q-Jet to an Edelbrock that flows, uh, 750cfm. uzzled:
It's all in the combination. Heavy cars with tight converters and tall gears generally don't do well with mech secondaries due to the slow climb in rpm. To take advantage of the fast opening mech secondaries, the airflow needs to rise quickly or you suffer the dreaded bog from hell. Give it some gears and/or higher stall and you can begin to reap the benefits. You can stay with the q-jet well into the higher horsepower numbers. Devon
Thanks. That's pretty much what I figured. The recommendation came from one of the techs at work, and their contention was "well, I put a mechanical secondary carb on my boat (which has a 460 in it) and it goes much better now". While I'm sure that's true, the 460 in the boat just has to spin a prop... There's a big difference between that and pushing around a 5500lb (including me and all the parts in the trunk) Buick.
Not to mention that the Q-Jet, as well as the Edelbrock/Carter carbs, are in fact mechanical secondary units. The difference being that they use an air valve above the throttle plates to moderate airflow, while Holley uses no other air metering--just a bigass squirt of accelerator pump.
Granted, but with the air valve they're functionally the same as vacuum secondary units, as far as I understood.
Essentially correct, with the q-jet handling secondary metering with better resolution than many others. Being able to tailor the air valve opening so closely is one factor of how Greg Gessler can launch his stock-appearing GS on bias ply tires and still break into the 10's. :Brow: Devon
I voted vacuum, only because I'd not have the talent to correctly adjust mechanical. I have to go with the easy-for-me one here.
I don't like the theory of vacuum secondaries. Your the one who pays for your gas so why can't you be the one who directly decides to open the secondaries?
I would think each carb properly tuned will perform very close to each other. Proper tuning being the keyword. I prefer the Edelbrocks but I know most people here are are fond of the Q-jets. But if your Q-Jet is junk you probably will see improvements.
