General Category > Quadrajet Carb Talk and Tips
How much hp can a quadrajet support?
Cliff Ruggles:
Keep in mind here that the Q-jet got an extremely BAD reputation from the very early models 65-67 that used the plunger-bypass fuel inlet deal. What POS. Didn't work back then, and still HOPELESS today.
In 1967 they started using a threaded in needle/seat set-up, but stuck with the early hinge pin location and HUGE float. These carbs are better than the first design, but still far inferior to the later set-ups.
By 1969 they figured out the float/fulcrum deal used a much better set-up, which could handle higher fuel pressures with a much smaller float.
By 1971, ever tightening emission standards had most q-jets so lean at idle, they wouldn't work on most applications beyond the pathetically underpowered small cammed low compression engines they were delivered on.
The problem is, or was, that the early units gave them such a bad reputation, folks just kept dumping Q-jets and buying Holley's, Carter AFB's, and Edelbrock AFB clones.
The truth here is, that once you get one dialed in for what you are doing, you can make as just as much power as anything else, and get a LOT better fuel economy for "normal" driving.
A few years ago, while we were dynoing one of my engines for the High Performance Pontiac and Popular Hot Roddings "Engine Masters" edition, the representative from the magazine asked us to do some carburetor comparisons. He said that he could get more coverage with additional articles on carburetor comparisons, etc. Available at the dyno shop were several well prepared Holley HP and Demon carbs.
I really didn't want to do the testing, figuring I'd get outran, just to see it in print a few months later, and have to hear about it on every website that supports this hobby for the next 15 to 20 years.
It sort of went like this. After all the testing was done, the dyno shop staff grabbed up a big fancy HP series Holley and said, "now lets see how much power this engine can really make"!
Well, it LOST right at 2HP and 3ft lbs torque.
We installed the engine back in my car a few days later, and tested the carbs back to back at the dragstrip.
The Q-jet was exactly .02 seconds quicker, and .30mph faster than the Holley.
The magazine representative did NOT follow up with any additional articles about this testing.....wonder why?.......Cliff
Paul:
Thats very incredible. If they would have posted the results I would guess it could have turned the tables for Holley and Quadrajets!
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