quadrajet vs edelbrock 1406

[cooter55]

I went through the same dilemma and opted to put another Q-jet on a dual drilled Performer 2.0 manifold on my 454. I just decided that the small primaries and vacuum secondaries gave me the best shot at NOT being OPEC's best friend. I'll let y'all know how it turns out next week.

 

[BADAZ chevy guy]

One thing that most people miss about Q-jets vs. Eddies and Hollies. The latter two are 'FIXED CFM' carbs. If you buy a 650 CFM that's what it will produce. And, that may end up being to much. Most Q-jets are a 'Veritable CFM' carb the maxes out at 750 CFM (although some were 850 CFM) Because of the secondary design, the Q-Jet will ONLY draw the required CFM for the engine and demand you're putting on it. ie: A stock 350cid will only draw about 550 CFM at WOT. So, the secondaries on the Q-Jet will NEVER open past the 550CFM position. Unlike the eddys and Hollies that are trying to force a fuel air mix from a 650CFM configuration.

 

[350runner]

One thing that most people miss about Q-jets vs. Eddies and Hollies. The latter two are 'FIXED CFM' carbs. If you buy a 650 CFM that's what it will produce. And, that may end up being to much. Most Q-jets are a 'Veritable CFM' carb the maxes out at 750 CFM (although some were 850 CFM) Because of the secondary design, the Q-Jet will ONLY draw the required CFM for the engine and demand you're putting on it. ie: A stock 350cid will only draw about 550 CFM at WOT. So, the secondaries on the Q-Jet will NEVER open past the 550CFM position. Unlike the eddys and Hollies that are trying to force a fuel air mix from a 650CFM configuration.

This^^^

 

[HotRodPC]

This is likely why a Qjet potentially put out better mpg #'s too if it's properly tuned and adjusted. It's not going to take more than it can use.

 

[350runner]

And why the off idle throttle response is night and day.

 

[rich weyand]

The engine draws what it needs. The Edelbrock in particular has a vacuum operated air plate on the secondaries. But the carb will not push more cfms than the engine draws.

The difference lies in the fact the the primaries are smaller on the Qjet. This means that you are running closer to the design stack velocity on the front barrels, and the throttle plate is more open, which means less restriction and turbulence. A carb is most efficient at the design stack velocity of the primaries. At cruise, the Eddy and Holly are running bigger primaries at lower stack velocities than the Qjet, so they can't get the same mileage.

Same conclusion, though I got there a different way.

 

[350runner]

They can't get the same mileage or off idle throttle response and that's what sucks. Then again what about that new quad spoofed holly demon... http://www.jegs.com/webapp/wcs/stor...002&langId=-1&productId=2060102&storeId=10001 someone want to be a guinea pig?